Diagnosing a Failed Emissions Test - High HC, CO and NOx Causes and Repairs

[@wysetech2000]

I have been an automotive tech for 47+ years and that has to be one of the best exhaust emission explanations I have ever seen anywhere. I just subscribed to your channel.

[@myRatchets]

+wysetech2000 Thank you sir, I appreciate your comment and subscription :-)

[@ReikoX7]

I am not any atuomotive tech, bu this explanations are great much more easily understandable compared to other stuff that I can find on the internet and all the stuff gives sense.

[@kevinllamido9647]

@@myRatchets I agree with @wysetch2000 This was excellent, simple and logically explained. and took a lot the guesswork and "randomness" of the suggested fixes. Very consumable. Thank you for taking the time to make this video.

[@johnneszmery5875]

This is the best resource ever!! Using this knowledge, today my 1990 Volvo 240DL with 246K miles passed with flying colors! The mechanic/tester was amazed at the low numbers. I've subscribed and thanks for everything, Man !!

[@osielzamora5613]

Thank you for your videos, you have a great way of putting all repair in a simple and clear manner. Coming from a person who has 24 year of automotive service . 👍🏽

[@apuuvah]

Very informative, thanx. Especially liked... 1) If NOx is a pass at idle, but a fail at higher rpm, EGR valve is faulty 2) If NOx is WAY above the limit (2-3x or more) catalytic converter is busted

[@carlosk8103]

Egr system... Usually EGR is good but dirty very rare for them to fail...

[@BellaRocko]

You make excellent informational and DIY videos! It's clear that you have a very good understanding of all auto related functions by how well you can explain them. The only thing that confuses me is why you don't have hundreds of thousands or millions of views and subscribers! Thank you very much for your videos!

[@wilsonbent4209]

great video man... the way you explain poor test results to the problem is phenomenal! thank you

[@TwoCarGaragez]

I always replace everything that’s cheap first. Check for vacuum/air leaks and exhaust leaks. Change your engine oil and oil filter. Change your air intake filter if it looks old. Change the O2 sensors. Add some Lucas fuel cleaner. Check your tire pressure (can make a difference on dyno smogs). Lastly, take it for a 20-30 min highway drive before getting it smogged. Leave it running until it’s tested.

[@datadavis]

I did all that. And welded in a new cat. New lambda plug. P.o.s corolla still wont pass for hich co and hc. Now it goes to africa. Bye byeeee! 😂

[@joelmccoin9727]

Excellent Video!!! Very well explained, very clear, helpful & useful. You are a good teacher, Thank you.

[@c.c.8841]

thanks for straight answers with no frills, some people are just unable or unwilling to do that and wastes everyones time.

[@richardpotter712]

Very good explanation. One other point is that if you have a thermostat that is stuck open and the engine runs colder than it should, the EMS will over compensate the fuel mixture and the engine will run too rich thus increasing the Co2 levels.

[@lanazaakat9466]

Please also keep in mind to use simple language for the common persons who don't have much auto experience and can't find an honest mechanic, especially in these times. . Thanks !! Good Job. I was able to change the timing belt, water pump, all pulleys etc. just by watching your videos and taking notes. !! My 1997 Camry 2.2 L now runs like a charm. I just passed smog. Time, knowledge, and tools are what one needs...Appreciate.

[@meperson]

I had issue with high hydrocarbons on my 1995 Toyota Corolla. I followed your instructions and replaced spark plugs and the problem was solved. Just for a good measure I used engine cleaner, put a new high mileage oil and high quality gasoline. Passed the DQ without any issues. Thank you very much!

[@jonnapatricia5191]

It’s a great and reliable video. Was facing this kinda issue back then with my emission test so I had to look for a way, which was how I came across Stray Admin who has got years in experience of helping lots of citizens pass they’re Smog test too.

[@calvinchou9367]

I had failed my smog test, and after seeing this video I knew what to do. My HC had failed, so I Knew it was the air mixture. I got a new air filter. I also got the "catclean" product...more cleaning. I then removed my negative battery terminal to reset computer. I even got more air in the tires. My HC was 145 when I failed, today it was at 6. Easy pass. Thanks for great video.

[@hayypapi4281]

My was 240 and max was 170 what do you think it could be

[@johnevon8220]

This is really great information for the consumer, Thank you for your time and effort in putting this all together.

[@jag376]

I’m sold man. You are way above my pay grade!!!! Thanks and as a diy guy, I appreciated the information.

[@testplatform582]

Thanks so much for sharing this info. You probably have saved hundreds of people from dishonest repair shops. More power to you Bro!

[@Engineer9736]

It’s my issue as well.. car failed emissions test, too much co. I don’t dare to bring it to a garage as i feel like they are going to jack up the price to crazy amounts. Or they break something small on purpose so they hope that i’ll be back later to them. Fixing it DIY prevents all that. Just takes a bit more time and headache…

[@omnidivisible]

Superb presentation. Good thing that I saved my emissions reports. Now I can use the information I learned from you and use the emissions reports to troubleshoot and maintain my car.

[@jesusgastelum9109]

I never comment or even subscribe. But I subscribed awhile ago. Ever since I was working on my Audi. You've saved me numerous times. Great work sir!!!

[@nathanaelnewton6299]

Very clearly explained-It just shows how a good explanation does not require all the other 'how great am I' platforming BS. Well done and thank you.

[@rondetorres3842]

Trying to keep MY93 4cl Toyota pick up on the road (work truck). Im pretty versed in "tail pipe" emissions and my "smog #'s) are getting close to not passing. I needed a refresher course on what it takes on my behalf to get my pick up to pass. Thanks for posting!!!

[@barryaugustine1298]

my hc co pass but nox off the charsts 1300 too high so, i changed egr and sensors and got vacuum lines working too distributer ,now im not smoking at idle ,not blowing white smoke i begin too take off ,so now on too cat then muffler thank you sir spot on those problems !!! i recommend getting spark plugs wires firing very very good so you can tell when driving after more power etc..

[@jeffarcher400]

Lacquer thinner in the gas is supposed to clean the catalytic converter. It's scary but I put some in my cars and it didn't kill them. It sounded more throaty but can't fix everything. Removing the cat and soaking in solvent is supposed to be the best. My mechanic recommended Seafoam for de carbonizing the engine but then all that goes into the catalytic converter. O2 sensors on eBay are dirt cheap but are they any good? Many plug wires and coils are junk. There's counterfeit products in very real looking packaging. The tip about tire pressure is golden!

[@capt251978]

Good job, buddy. Been a tech for 20 years and live in a rural area so... we are not required to perform emissions testing. Trying to get a grasp on it.. thanks.

[@Engineerboy100]

Good thorough smog prep. review. Thanks. Now I gotta go out and change plugs, clean MAF, run some sea foam through the intake and drive her hard to the smog shop ;)

[@ArelSprite]

You should be a professor in KZbin university This was the greatest Emissions video I’ve ever seen

[@paul-wh1co]

Thank you. This has to be the best explanation for emissions I have ever seen. I also just subscribed

[@r.pratherray1364]

So informative! My mechanic and the smog guys have been giving me the run around. After watching this video, I feel armed with useful information that I can take to my mechanic and have my car pass smog.

[@voyage1der449]

Dude thank you so much my 95 civic failed the HC and NoX but just by by a little. My HC was at 0.87 and to pass it has to be 0.80 and my NoX was at 2.60 and to pass it need to be at 2.00 now I know what to look for and try to fix it

[@jamespowton4596]

Excellent insight into high Co + Hc narrowing the component replacement decision markedly.A1

[@sparsa3855]

Hey, Its a practical way of understanding & analyzing the reasons behind failing Emission diagnostic tests, and finding how to deal with to remedy the caused dilemma. thanks for well elaborated & right to point explanation . S. Parsa Feb/2020

[@patrickdurham8393]

This is an excellent video. Answered so many questions that I had in a way I could understand. Keep it up dude!

[@harlangreen1840]

WORN DISTRIBUTOR CAN CAUSE ISSUES AS WELL...NICE JOB WITH THIS VIDEO

[@fishodorvagina]

When I finish my automotive tech school here in Florida, I'm going to California to learn about vehicle emissions to further my education.

[@thewolfpackgarage5046]

fishodorvagina did you ever come to California ?

[@chriskeiley5343]

this is a pretty good explanation, however it is incomplete. one big thing that most people often over look is carbon build up which can increase cyl pressures and temp's leading to elevated nox emissions, another thing is a rich condition can do the same thing because the cyl pres be higher, along thos same lines is if the head has been machined after a bad warp. on some vehicles i have observed that too much fuel pressure can actually cause high hc's instead of co. every car is different but still a very good video

[@nooretautaya]

Hi. Is there a simple device that could help me test my Co2 emission from my car? What is your opinion about the Carbon Cleaning Decarbonizing..Thanks.

[@tasadar1695]

you sir have the best video of explaining this, thank you. subscribed.

[@williamcarpenter79]

Multiple thumbs up mien Doctor! Teaching is your forte, thank you!

[@c86tail]

Miss great videos like these from your channel. Very informative.

[@ElizabethDiaz-bi1qy]

Thanks for the video i hope i can get my 95 E420 Benz to pass with this information! I do understand it's an old car and will probably have to make repairs each year but i got a good guide, you.

[@mansor74]

My 2008 Nissan Altima failed the emission test and were struggled long to find the cause. Ignition coil, Sparkplug, Injectors, MAF, PCV valve, Oxygen sensors, Catalytic converter, Piston rings everything was addressed but the problem still persisted. Finally, someone noticed that the temperature gauge was always showing a very low value. And it was found the thermostat valve was faulty and was stuck open and the ECU was sensing it as cold start condition always and the fuel air ratio was running rich. The fuel economy also improved a lot after replacing the thermostat valve but I miss the sporty acceleration and pick-up when it was running rich. Thought might be useful to someone going through a similar trouble.

[@YoDoneSa]

wonderful, I love your videos. There are very good explained and. keep up the good work. good luck from here in The Netherlands

[@MikeKollin]

Failed smog test. Failed 15 mph test. 100 over PPM at 608. I put new plugs and wires, replaced Head gasket kit 4 months ago. O2 Sensor is fairly new, replaced it 4 years ago on last smog. And also replaced Catalytic converter same time 4 years ago by pro shop that specializes in muffler and Catalytic converters. Had shop rebuild engine 5 years ago. It's really strong engine. Tonight I replaced air filter and put in Guaranteed to pass Fluid. going to replace Fuel Filter tomorrow! Emission test results on fail say: CO2 is 17.4, O2 is 0.0 and again 100 over NO PPM at 608. Any thoughts?

[@defons1234]

Thank you very much,great video and explanation, my 1998 Bmw 740il failed smog with high nox at 2500rpm, if you are in california I will ring my car to you.

[@thedeathwobblechannel6539]

if you have the original catalytic converter it may need replacing. they do go bad.

[@memomunoz2266]

@@thedeathwobblechannel6539 so a car that has the original catalytic converter(about 23 year's old) from 1997 should just be replaced with a new one?

[@thedeathwobblechannel6539]

@@memomunoz2266 mine had the honeycomb break apart and would go sideways to the flow and choke off my engine. The "go bad" when the honeycomb breaks. It has no moving parts and no replaceable parts. If it clogs replace it

[@MrForcat]

As others say, best emissions lesson!

[@annesmith3490]

This was a very helpful video, just had to clean my MAF because my K&N ended up leaking oil onto it which affected its ability to read, no check engine light :/

[@joseleon2416]

Excellent explanation, excellent. Keep that humble attitude. I did suscribe.

[@leonminja7922]

I like the way you explain, I got it clear.

[@myRatchets]

+leon minja Glad you like the video, thanks for commenting.

[@mohamedamer8833]

Thanks for the information....Does high oil consumption cause high HC?

[@roberthunker8957]

Over here you get your car back ( a 1976 carbureted 4 cylinder ) didn't pass the Emissions test the problem is that it's undriveable when it did pass. So when you finally did make it home you get a few screw drivers and fiddle around for 2 days so it doesn't use crazy amounts of fuel and runs as it did. No one who bothers you for another 2 years. It probably would have passed in 1976. The only way for it to pass and run as it should is an LPG installation. For new cars guess you covered them all.

[@josueivanruiz]

Exhaust leaks are also something that should not be overlooked bc depending on the location, it can skew oxygen sensor readings, or cause very high NOx levels if its located before the catalytic converter but after the upstream oxygen sensor. The extra oxygen lowers the catalysts ability to reduce NOx.

[@rabitoblanco]

+josue ruiz This is an interesting point you bring up! I am trying to diagnose 2x the amount of Nox allowed, and I have all new plugs/wires/dist. cap/rotor, new cat and back exhaust system and recent flush/filled radiator (with no signs of problems) and the car runs just fine, BUT I think I can hear a leak at the exhaust manifold, so this could be my issue! +RatchetsAnd Wrenches Really nicely laid out explanations and walk-through! Thank you.

[@marysolpantoja8677]

So great video ,it help a lot unfortunately my car 2002 Toyota echo won't pass the emission test,ND needs some cosmetic work ...(N-0 ×) .

[@Funny_How]

Josue--Interesting. My HC & CO are ridiculously low (like 20% of max) but my NO is triple the Max!

[@josueivanruiz]

@@Funny_How CO and NOx have an inverse relationship. When one is high the other is low and vice versa. Sometimes both can be high but that usually means a bad catalytic converter and is usually the last repair once all other systems have been checked and confirmed to be operating properly

[@Funny_How]

@@josueivanruiz Thank you!

[@IMMU16]

Hi first of all thank you very much for this video i got so much knowledge by this video i always check videos relating to car fix but never seen someone explaining like this . i have one question i drive 1.4 petrol car 3 months back engine warning light came up there was a problem with o2 sensors but i replaced 2 sensors but stll engine light stays on few days later i reset that light but next day engine warning light came back again brought to garage they checked there was a problem with exhaust was leaking they fixed it and last week i brought my car to pass emission test they failed because of high Hc and co and the warning light came back again.so can you please tell me what could be the problem thank you.

[@lukemartin7029]

nice use of the white board!! :)

[@redneckkorean303]

Very helpful Can you do a vid on adjusting timing/idle and af mixture on carbureted engine

[@jimmythehood4011]

Every year my 97 Dodge Caravan gets closer to failing the emissions test and this last time it did fail on the HC part of the test, when it measured 62 ppm when it was only allowed a max of 51 ppm. So I decided to try filling it with E85 Ethanol on a almost empty tank and it worked. When I took it back for a retest it drastically reduced the Hydrocarbons (also the CO and NOx) and I passed easily! I recommend anyone who is a borderline fail to give it a try because it worked better than additives and other methods that I tried and didn't work.

[@datadavis]

51ppm? Thats insanely low, it would have to run on water vapors, 510ppm more likely? 200ppm is the limit in sweden.

[@Kodo9mm]

Great, full of knowledge, i appreciate you making this video man.

[@user-ru2hf1sg4e]

Great video going for my l1 this helps a lot

[@jeremiahlyleseditor437]

Hey man. Nice Video. It's a big help. I have the opposite issue on the NO failure. High values at idle but normal over 2500. Would it still be the EGR or the relay?

[@cantweallgetalong]

I have a 95 jeep g cherokee 4.0 that is passing 15 mph test and failing 25 mph NOX, but no EGR system on this year, any thoughts or direction? 260K and still has good power and acceleration. New CAT fixed 15 mph high NOX, but not 25 mph. Also put a new O2 sensor on 6 months ago to fix rough idle and check engine light. Added new plugs, cap and rotor, but wires still look new. New air cleaner and oil change and coolant is fresh and topped off in radiator. No vacuum leaks detected.

[@buyherepayheresanjo]

Great explanation.

[@nikmamad]

short, put right to the point, Thank you,

[@mfable1985]

well taught. i learnt something today! Good video.

[@robbieh1297]

Very good and informative video, well done 👍

[@LeslieLello]

I have a 2002 Saturn SL Sport sedan and an inspection coming up soon. I have been told that I will not pass this year because a lot of the sensors are failing, not because of any known exhaust issues at this point. One shop quoted $1000 to replace all the sensors which doesn't make sense for a 15 year old car. But I love my car and would love to keep it. Another mechanic monitored my car on the highway for 15 minutes and said that my car was "running cooler than it should" and he wanted to replace the transmission. Again, I'm wondering if it is a good idea to put money into a 15 year old car, even though I love it. If I was in CA I would come to your shop! :-)

[@thedeathwobblechannel6539]

get your car tested, never do what a shop says. too many crooks out there to screw over women. get the printout from the test then go from there.

[@joseymarine4095]

im a tech here in CA here are some tips : for the years 2000 and up. they use a new machine only checks obd 2 so no check engine light and all monitors completed expect evap will pass your test . for 1999 and older your car will go on the dyno if its 1996 and newer you will not pass if you have the check engine light on , computer picks it up and fails the car automatically even if you do good on the dyno. for 1995 and older you "can" depending on the shop pass with the light on and monitors incomplete since you will not communicate with computer , it will be a visual inspection at that point . but most likely if you have a light on for like a misfire or something your car will not pass the emissions test since it wont burn the fuel properly

[@hayypapi4281]

Josey Marine I have a 95 truck and emission test fail HC was high at 240

[@Molinajme]

Presentation well explained

[@clarencetrinidad9149]

Thanks for making this video. But I have a question about NOx. If I have excessive high NOx at 15mph but lower than avg for 25mpg, can I rule out a bad catalytic coverter?

[@JediGokuLee]

Clarence, I thought the same thing for my car (same scenario) but as my CO is very low at both speeds I’m ruling out a bad cat for now and focusing on plugs/wires first (partially focusing on cheaper fixes before hitting the big $$ items). As you commented three months ago and I suspect you had an emissions issue, whatever became of your circumstance? Did you figure out what was wrong?

[@deanhofmans9667]

Thank you sir. May god richly bless you

[@carslover3509]

very very great information i learned to much thanks friend keep the good work

[@maxoct7331]

i like the info in this clip and i know its 3 years old but can you shine a light about the the diffrent readings of CO, HC and NOx in relation to each others and what does that indicate. i willing to buy a lexus gs300 the price is less than 2000$ because it failed in the emmesion test because of high CO and not the others is it worth buying and fixing?

[@Tubecraft1]

Thankyou for such a good and thorough vid

[@Mr.Monta77]

I wonder if all this knowledge will be superfluous with the electric car taking over the market. Reminds me of analog film and digital camera technology. Interesting times.

[@bryanespinal7107]

by "A/F" i thought you meant the bulgar abreviation AF loll xD my mind is just dirtier than a catalytic

[@eluberimabib4070]

Great video

[@wagakamakoyo7309]

I just subscribed man. Excellent videos!

[@geronimorodriguez9851]

I have 95 sierra 1500 and nox failed at 1500 rpm but passed at 2500 rpm any suggestion of what component might be failing? Any suggestions would help thanks in advance.

[@mick2d2]

Thanks for the great explanation.

[@knockout35189]

good info. can you tell me how clogged air filter would affect with high hc or co? The maf sensor is going to measure whatever air comes in through the filter so if a filter is clogged then the maf sensor would just measure whatever the amount of air there is and fuel will be delivered according to that.

[@PhilVerryChannel]

Wonderful points. Well said.

[@aramieg8128]

really good video., I must admit that it takes balls to be in front of a camera and to try to explain all of this info to the general public. Btw you forgot to mention the words "at sea level" 14.7 - 1 ratio at sea level. LOL You have a very confused look. I like how you look and sound like you're guessing. I've been a smog tech since 1990. and I have 2 fancy laminated lists on my shop wall for my customers. #1 If the HC and or NO is slight elevated over the MAX that means you have Carbon build up. Run some injector cleaner through the tank. That's about 300 miles or so for most vehicles. that will clean up the carbon build up. if the CO is elevated replace the O2 sensor. if you have close to or over 200K on the odometer then it's time for the Cat. there are a few different test we can do in the field to check the Cat. with my experience most cars go about 200K before the cat dies. May God rest all of the 9 lives.

[@jokjoksson4369]

Great vid! Thanks.

[@DominicUbble]

I have a 1995 Mercury Mistique with a 2.5 V6. The passages in the plenum behind the gasket of the throttle body were completely clogged and the EGR tube had a split in it so I had multiple things wrong and this caused me to fail the emissions test.

[@huthyfaqahtaan2804]

Thank you for the explanation, I need and advice on that I have removed the ECM from my BMW Z3 1998 and return it back immediately, but I got the engine shaking and vibrating.. is there any explanation to this issue????

[@shawndiesel007]

Thanks for the video! Very informative. For NOx I had the opposite issue; failed at 15mph, 1350rpm (55% over max) and passed at 25mph, 2200rpm (20% of max). Could this still be EGR or likely something else?

[@goku0728995]

I have the same issue, did you ever find out if it was the egr valve? Thanks!

[@shawndiesel007]

@@goku0728995 haven't touched EGR but don't think that was it; I did an oil and air filter change and NOx passed. I also made sure my engine was much warmer; first time the smog shop was like a mile from my house. Still failing HC at 15mph though, getting 59 with a 51 max allowable 🤦

[@tommygunn7745]

Good explanation:,Now did I understand it,here I go: My 1990 351 windsor failed this part of the KaliforniaSmogTest: " The idle 2000 rpm hydrocarbon"portion of the test.The max acceptable HC was 120 but it was 140when tested. . Before the test I had changed the plugs and the wires. With that and what I think I got from your video, Im thinkin its either the pre cat sensor or the exaust manifold cracks that are effecting the AFRatio to the lean side. Is this close? My dash seems not to have any check engine lights that come on. Is that possible? i thought you said a partial failing precat sensor might not trigger svc light.

[@hayypapi4281]

Tommy Gunn or maybe the catalyst I have the same problem the HC was 170 and 240 when it tasted

[@LD-ow6ec]

What if the car doesn’t have EGR? Would fixing everything else give higher chance of passing even if EGR isn’t present?

[@mccauley444]

Who the hell down voted this excellent explanation?

[@LuisDiaz-cb3rq]

Great video, I have a 1990 Mazda Truck B2600 2 WD, problems at 25 mph on the NO (PPM) and my truck does not have an EGR. I am working on the solution, any ideas??? Thank you,

[@ericelder2962]

Gr8 info

[@meegel]

If the cat is going bad and letting a ton of nox through, would it not fail the ECS check?

[@carreteras101]

great explanation. thanks again.

[@E17AutoServisZadar]

The best explanation ive seen to date. Thanks for your effort.

[@ElgarajedeJoseManuelH]

Really goog video. Thank you so much.

[@johndonohue7746]

Hi Very informative video. Thank you. I have a question. I recently failed nox in Colorado on my 2002 nissan pathfinder, but not by much. The new limit is 1.5 grams per mile. Originally, I was 1.7 gpm. I changed the plugs. Then at 1.69. Changed the left catalytic converter. Nox was now at 1.5765 gpm. By the way, I'm fully passing hc and Co from the beginning of this fiasco. I should mention that the new cat is carb compliant. The right cat I changed to an epa compliant unit 2 years ago because Colorado hadn't gone all Radical on the carb stds yet. So now what to do? I am faced with changing the other cat again, maybe thermostat or maybe egr solenoid? Also the car is running fine and no codes are on the obd scanner. So the nissan thinks everything is just perfect and it would be if I lived in the 46 other states not run by folks that are from California. Thing is, I haven't been able to find a vacuum leak either. I'm worried that buying another carb cat for the right side won't solve the issue. I even thought maybe there's a pcv valve or fuel injection issue but it's impossible to know. So I was hoping you could give me your opinion on how to approach it. Thanks.

[@PimptatoPCs]

Did you replace the other EPA cat with a CARB cat? Did you get it to pass yet?

[@johndonohue7746]

@PimptatoPCs no, I had to get a waiver. They claim my epa cat on the passenger side was keeping it from passing. The carb cat works fine on the driver side. I'm at 1.57 gpm. They gave me 2 years to change the other cat which is the next emissions inspection basically. It's ridiculous because a 20 year old car isn't designed for this. It's Colorado and CA that have their head so far up their ass that they can't understand that.

[@archiewilson4943]

@@johndonohue7746 that's close to one of numbers I'm at. I'm going to try dumping some CRC additive into it and 100 octane race fuel. I am also going to over inflate the rear tires and I may take out the air filter for the test. If it doesn't work how did you get a waiver?

[@robertohernandez170]

thank you bro very good information.

[@cuttyzonthebeat9634]

I just failed because my Hc levels were to high by 10 and NO was to hogh by 30 im wondering what it can be the smog technician said it wasn't bad at all any thoughts?

[@eru7774]

Best explanation!!! Thank you!!! Keep it up

[@richardbruce8514]

Thanks that was good info.

[@edwinmoreira3370]

I have Toyota t100 1997 need smog

[@roontunes]

very helpful thank you

[@s_l_family9060]

Hi i just bought a bmw 116i 2007 just checked its mot and its got (Exhaust carbon monoxide content at idle exceeds manufacturer's specified limits) (Exhaust carbon monoxide content after 2nd fast idle exceeds manufacturer's specified limits). Been to the mechanics changed the nox sensor on it that works fine and the other code was upstream oxygen sensors so the lamba sensor came up if i change that does that fixes it ? And have u got rough idles and less power cant pick up speed that much when the car warms up when the car is currently cold not warmed up it runs and got power to it