How to Test an Oxygen or O2 Sensor - Plus a Quick Guide on What Each Sensor Wire is For

Here is a quick video I made on how you can test an Oxygen Sensor and also what different types of sensors are out there and whats the job of each wire on these sensors.
Links to Tools and Equipment Used in the Video:
Multimeter Used in Video: amzn.to/2bngr5q
Propane Regulator: amzn.to/2b76gpi
Propane Cylinder: amzn.to/2b76P2e
If you found this video helpful please check out these other video's as well:
How to diagnose and fix no heat issues: • How to Diagnose and Fi...
How to test an alternator: • How to Test an Alterna...
How to Test a Car Battery: • How to Test a Car Batt...
How to Find a Parasitic Draw: • How to Perform a Paras...
How to Replace an Alternator: • How to Replace an Alte...
If this video helped you out please don't forget to subscribe, give it a thumbs up or if you are feeling generous leaving a tip by clicking the " i " button on the top left corner of the screen. Thank you very much for your support!
Disclaimer:
Due to factors beyond the control of Ratchetsand Wrenches, it cannot guarantee against unauthorized modifications of this information, or improper use of this information. Ratchetsand Wrenches assumes no liability for any property or personal damage that may arise from doing a repair on your vehicle after watching any of my repair video's. Due to factors beyond the control of Ratchetsand Wrenches, no information contained in this video shall create any express or implied warranty or guarantee of any particular result. Again Any injury, damage or loss that may result from improper use of tools, equipment, or the information contained in this video is the sole responsibility of the user and not Ratchetsand Wrenches.

[@tomhandzik2968]

Been a tech 50 years. Best and simplest explanation I’ve heard!!! Great job!!!!

[@orbnitsky]

I think you did a good job of explaining and keeping the methods and results in perspective! It may not catch all problems but it will save lots of $ for lots of folks.

[@sameobiggy]

Great video! Finally found a video that explained what the wires are and differences between them and how to bench test them. Great job!

[@kriskent7805]

P]

[@joemikos9155]

Absolutely great demo on o2 sensor. Was ASE cert mech for 25 yrs. Often found mechanics/teachers made assumptions on trainees basic knowledge. It was impressive you took the time to give detailed explanation. You would make a great teacher. Wish I had you as a forman when I had my shop. Don't think you were born yet. Lol Thank you

[@myRatchets]

Joe Mikos Thanks for the kind words, you would not want me as your forman. I sleep on the job all the time hahha

[@joemikos9155]

LOL for real! I wish you the best and look forward to watching more vids. I have been out of commision with long cancer battle but doing fine now. After over ten years I have to do a lot of retraining. Things have changed a lot as you know. Will definitely be watching and responding in the future. Thanks again👍

[@MC-hs4mf]

@@myRatchets p2195 code???

[@TheHeatingEngineer]

Thanks for the info. Very helpful. just in case no one has mentioned it, the heating effect of a resistance is Watts=(volts x volts) / Resistance. For a 7.2ohm resistance on a 12volt system this is 20Watts. This is a low heating effect, but added to the heat from the exhaust gases I guess it will achieve a two to three hundred degrees celsius.

[@aaronwarman71]

this is a great explanation, the heater resistance is round about 4 ohms but does vary slightly from sensor to sensor, the sensor reading will rapidly change once the sensor is fully heated all the way around, using the blowtorch is definitely a near as damn it simulation of what the sensor will be experiencing in the exhaust manifold, this is a great way to test an existing sensor and a brand new one before fitting it, it is also a good idea to check the resistance reading of the sensor wires as there should be no resistance reading across it, if it does have resistance then it means that there is carbon crud bridging the sensor wire itself and this build up on an old sensor will cause false readings to the ecu.

[@blackbirdpie217]

An analog meter with a needle would show if the sensor has a faster reaction. That's the downside of the digital multi meters, you're not only looking at how fast the component is switching, the digital meter has a limited refresh rate.

[@RussellBooth1977]

A scan tool is the best way to test it with the O2 sensor(s) in situ. If it's both a code reader & one that scans live data,then it will tell you if the sensor is at fault or whether they are reporting a lean mixture due to an air leak or bad fuel pressure. For example , code for a MAF meter & an O2 sensor reporting a lean mixture will tell you that you may have an air leak.

[@davidbrown8629]

Thank you for your videos. They are easy to understand and have been a great help! Good job!

[@BuddysDIY]

I always recommend my subs to your channel when they asks what other Automotive KZbinrs they should check out. Awesome video

[@danielfuentes5428]

Subscribed

[@BuddysDIY]

@@danielfuentes5428 r&r is a beast.

[@diehardfan173]

I used the four wire explanation and parts and found two bad sensors. And better to hold torch below sensor head to create a fire shield rather to one side around sensor head! Thanks for taking time to educate the public.

[@chriswood476]

Finally a down to the point video. Thank you.

[@chinyeesiang6642]

Finaly someone that properly explains each wire.!

[@pirihern9329]

Thanks just learned something new

[@phillipsmith1847]

Your videos are always so good. Thanks!

[@andrewedwards3426]

Great video, really helps me! I'm chasing a P2195 (Oxygen Sensor Biased/Stuck Lean, Bank 1, Sensor 1) on my Ford Focus. I've eliminated all other possible causes (vac leaks, exhaust leaks, etc) and have been scratching my head. I replaced my upstream sensor before anything, but I used the cheapest one I could find. This might be my problem, so I'm doing this procedure to check it. Thanks from a new subscriber!

[@theloosemoose8200]

Andrew Edwards don't forget a clogged fuel injector

[@merlingeikie]

Well done. simple and direct and low cost. Greetings from downunder oz

[@samg5543]

The best way to test the sensor is to backprobe the signal wires with it in the car and the engine RPM held above idle. The sensor could be producing a good signal, but the wiring to the PCM could be bad, preventing the signal from getting there. A scan tool is great, but that doesn't always mean the signal reported to the scan tool is correct.

[@alexxustube]

Very informative. Thanks a lot!

[@eddiehill6665]

Hey man, thanks for your video. I have seen another video of yours on touch up painting a car and enjoyed that one. Keep up the good work.

[@fredflinstone7939]

Just a caveat - some 2 wire sensors; 1 wire is the signal, 2nd wire is the heater, both utilizing the same ground. Nice video....

[@girohead]

You're a good instructor, I'm giving up on the forums and shops, they've all become jerks who just throw parts at things. I'm hoping this is my problem, I've tried new MAF sensor for P0171 because a shop wanted $500 for that and valve cover gasket (not needed), so I knew they were just throwing parts, at my expense. But I thought 'how can I test sensor without scanner?' I suspect these at 180k miles before my MAF sensor because I also got cat codes in past, like 'catalytic inefficiency' or something. I guess it could be MAF but I've tried two.

[@jasona8396]

Great video, just what I needed! Thanks my friend

[@michaelsimpson6094]

Man i love your videos informative and humorous and we'll explained keep up the good work man 👍

[@RNcooley]

Clear and concise best video out there.

[@haywire17]

Wells tech published VHS tapes on this method back in the OBD1 days, and I found the same thing as you - during testing of sensors that were "sluggish", the heat from the flame (making the o2 sensor cherry red) literally burned off deposits, and "fixed" sluggish sensors (sort of like the self-clean cycle in your kitchen oven). During normal operation, EGT's on a gasoline engine don't get hot enough to burn off these deposits that can foul a sensor over time... but your torch with the pinpoint flame can, and the test procedure itself "fixes" many of the sensors that trip an OBD code for "sluggish", or "slow response". Obviously not going to fix an "open heater" though...BTW - don't bang on the exhaust pipe, or use a hammer on your wrench, or drop the sensor when removing it...or you WILL have an open heater circuit by the time you want to reinstall it... ask me how I know...

[@UberAlphaSirus]

How I know?

[@fuzzyfish80549]

Or better yet, don't ask me how I know.

[@markfothebeast]

Whoa! Thanks for the tip. I never once thought of that!

[@erniecarrasco9107]

So are you recommending that we torch all our O2 sensors red hot and then reinstall them?

[@ScottysDetailing]

Great! Video I always wondered how to test O2 sensors. Just subbed. 👍

[@myRatchets]

***** Welcome aboard, thanks for watching.

[@Engineerboy100]

Good job on the video. Nice refresher Thanks!

[@shadowofzeus6267]

very simple way to explain things - thanks!

[@onesourishpuma1766]

Managed to hook up my afr gauge thanks to you mate.

[@MR-hc9uh]

That's great mate. Thank you! Really helpful!

[@hodgie542]

Really good video! Thank you

[@pooja-ov7xl]

Hello can i interface this sensor with any microcontroller for college level project??

[@notoco1199]

O2 sensors get cleaned in temperature above 400'c city driving on low revs is not good for them especially on LPG-that's what I did:-) at first O2 sensor was cold what you did with propane torch is not only heat him up but cleaning :-) so at first was lazy because was cold and dirty... Is not that easy to reach 400'c on 1.3 petrol yaris on motorway :-) I did the same by giving my O2 sensor good blast with propane torch and it works a lot better!!! Good video mate! Thumbs up!

[@MrScoobydoo12]

Very good info. Thanks

[@RaceLab37]

Very good video, thanks!

[@bl0ckbust3r]

great vid!

[@neostarfromearth107]

Thank you, good explanation.

[@reikoinaz]

very detailed. thanks

[@Kyle-ev4fk]

Thanks bro! This is going to help me big time.

[@lodhiautos9761]

Nice video. Thanks

[@philtulk9180]

Thank you, very helpful.

[@mrautoguy8419]

Great video! I have a 2006 Kia spectra 2.0l with codes p0171 and p2243. I have a 5wire oxygen sensor for the upstream. Call pls tell me how to test this sensor?

[@mtrltoolman]

great video thanks.

[@dlroberts20020]

Hello any advice... I have a 2005 Trailblazer and getting codes : P0153 and P0054 and P0053. I recently placed both O2 sensors and still have the codes. Could it be the Cat?

[@Ecosteven]

That's usually the next Step

[@karikko101]

you are best teacher :) i have i think wats all yours video thanks

[@jurosmilkovich1427]

How did the multimeter probes attach to the Oxygen Sensor for the voltage test?

[@Franklinveterinarycenter1of4]

The O2 sensor's sensing ability comes about by producing a small voltage proportionate to the exhaust oxygen content. In other words, if the oxygen content is low it produces a high voltage (0.90 Volts - Rich mixture) and if the oxygen content is high it produces a low voltage (0.10 Volts - Lean mixture). Give time for the torch to burn off carbon and heat the tip all around and not just one side.

[@kennynvake4hve584]

How do you check it on a 1995 vehicle that DONT have a scanner connection? My system is a OBDI system...I guess I could unplug it and see if it runs better or changes....I have a miss...at idle..or any speed or any acceleration...It was missing on 1 cylinder before I replaces the spark plugs...but It still makes a 'bump' or miss once in a while...

[@sandyorencia5876]

need help. My sister ford everest 2007model. When I drive and push the accelerator it suddenlly off the engine and it flashes the check engine. I tried to full tank and the chk engine gone and it does not power off. I used the car for a week. now when the fuel is low it came back it suddenly flash the chk engine and goes off while driving. need help whats the problem. is it the fuel tank has water in it? when i turn on the car without driving its ok no chk engine but when i drive and push the accelerator to make it run fast sometimes it will flash chk engine then off the engine.

[@diehardfan173]

I wish I could have seen the alligator clip and the smaller parts more closely other wise thanks much!

[@hardstylemexmendez1844]

Thank you 👌🙏👏

[@Splashfun2000]

I have a BlueDriver Bluetooth scanner but want to upgrade, what do you recommend as a good all around scanner that has good graphing capability ? Second my daughters 2011 Kia Sorento has basically really slow acceleration, no power on hills, the only code is P0170 which could be bad O2 sensor, bad Maf sensor, vacuum leak, etc, could that throw it into limp mode, I own 2 Optimas and a Santa Fe and even with bad O2 sensors they haven't lost power. Could it be transmission ?

[@khndenmark]

Great info

[@Splashfun2000]

Will this test work for a 5 wire sensor ? I can't seem to find a combination of wires that give an output ? Its a NTK sensor off a 2011Kia Sorento.

[@raymondrodriguez9283]

I have 2002 Pontiac Bonneville sle 3.8 .their is a loud bang and the motor will not crank to me it feels like it is out of time. I know the wires are in the right plugs i put new plugs and wires .pleas how do I fix this what do U think I am doing wrong

[@christianwoodley7699]

Can someone please help. I have a 2006 Suburu Impreza R with a 2010 Impreza engine in it. It’s throwing the code P0031 (heated O2 sensor circuit low bank 1 sensor 1). I’ve tested the harness for power with the ignition on and gotten 12.8 V and then the resistance on the sensor with a reading of 2.2 Ohms. What else could be causing the problem? It’s driving me nuts. The engine struggled for power under 3K rpm in 1st-3rd gear. I reset everything and cleared the code to see if it did anything and now the car is running like it’s brand new, the P0031 code is back as a pending code however it’s no longer causing a CEL on the dash. What other diagnostics can I do?

[@banajeckvelasco3548]

hi there, just wanna ask if this is one of the reason why idle drops when coming into a full-stop and causes the engine to stall???

[@kymountainman2213]

Yes, rough idle/cut-out during idle can be a common reaction to failing O2 sensor. Your car mixes fuel/air ratio based on data from the O2 sensor. If it mixes too lean (not enough fuel), the ratio may not be enough to continue firing, and the engine may even die completely. If mix is too rich (not enough air), incomplete combustion can occur. This may happen more commonly when first driving (especially if your O2 sensor is an unheated one), before engine & exhaust reaches normal operating temperature.

[@AJDRAGON01]

Hi, I just did this test on my o2 sensor, and is the voltage supposed to go back up on it owen after it drops down to zero? I did the test just like you and the voltage went up to .93v and immediately droped to 0v but then started climbing back up to .23v for about a minute and then started going back down to zero which took another minute.

[@lordmosess1]

Radiant heat. That would be fine

[@ZenithClarity]

Good job.

[@Casper01sa]

Thnx Man As allways your info is the best :). Plus i almost never comment. Un less it was helpfull.

[@georgekontopoulos]

Nice video. I am having a simple question. Did you heat the sensor (on time 5:15) with a gas tank or with a propane tank?

[@AFlyingSwive]

Looks like a butane torch, I get mine from lowes

[@natep9997]

My car is reading no activity from my 02 sensor that I just installed. The old one was throwing a code but it at least had activity. I tested the new o2 and it read 0.00 and then barely moved up to 0.01 to the highest it reached was 0.13 then to 0.03 and then 0.00 right away. It's that a bad o2 sensor? The brand new one?

[@rcdufffy]

Thanks, great video Easy to understand, keep up the good work.

[@b4322558]

what is making my 02 stay in open loop ?

[@elomeli211]

If I wire a bunch of 02 sensors in series than throw them into a fire, can they create enough voltage to power my daughter's boyfriend metal camp bed? Asking for a friend.

[@GameLover1022]

Did it work?

[@azizhachimi8744]

Enrique Oh yeh bud, they will produce between 1.5 and 3.2 KW which will be enough to warm the bed, cook the dinner and keep the barn warm too for the cow, the goats, the three ducks and the newly born piglets...it's cold down there in Alaska buddy!

[@ioanpop8578]

@@azizhachimi8744 ;-) :-)

[@danstray2527]

hahahahaha omg thanks!

[@adanarceo4636]

Thanks brother 👍👍👍

[@alfredomarquez9777]

HEY! You are OVERHEATING the sensor tip, and also RISKING it because you are overheating only ONE SIDE, and that stresses the ceramic inside! The PROPER way is to Only heat to a dull, dark red, and no more and doing it in a well shaded room to be able to see the first subtle red color just appearing and then withdrawing the flame immedoately!. Heating and turning the sensor to heat its tip area UNIFORMLY around, and not concentrating the heat at one side prevents stressing the ceramic inside, as it is fragile. You may add the caution about not heating the rear portion (behind the hexagon), as you could damage the heater element, thus, the only portion to heat, is the very tip of the sensor, also trying to make the tip of the flame to enter inside the holes, in order to decarbonize the ceramic inside the outer metal jacket, that cover is only there to protect the ceramic and its delicate precious metal deposits, which are what generates the voltage signal. Someone could presume that heating to bright red color didn't damagep his sensor, but not all sensors are so rugged as the factory installed ones, the after market ones tend to be less rugged (and sometimes less durable too!) Best wishes.

[@mrautoguy8419]

I used my scanner and with the engine at normal temperature. The sensor voltage goes a little above 2volts and my long term fuel trim stays at 25%.

[@jcaleca60]

Where would you find the specifications on your car I guess on the internet what's a good oscilloscope to check the engine if it's not too expensive for the Weekend Warrior on cars

[@petrpetr9334]

please, is the voltage also measured on the two white wires as resistance? Is it enough to use a candle to create a flame? Next time do a test on the Map and Maf sensor thanks for the video👍

[@liyangtime]

Have a question, is this o2 sensor upstream or downstream, is there any different in testing?

[@Suicidebunny666]

Mr. Yang did you every find out?

[@woofwoof6204]

good stuff.

[@jesusmoya1575]

if i get a coed that says heater control curcit low voltage.. bank 1 sensor 2 but i replace both oxyen sensors what would my next step be? thanks

[@gordbaker896]

Replace the O2 sensor furthest from the engine, likely past the Cat. Bank one on V engines is on the side #1 Cyl is on.

[@fixit9888]

Hi, thanks for the video. I checked my downstream O2 sensor on a 2010 CRV using a M1015B multimeter ( the sensor contains two white, one black and one grey wire) and i got no reading on both white wires. I tried the other wires and i also got nothing. I set the multimeter to the continuity setting x10. Am i doing something wrong?

[@alejandroespinoza3686]

Great video! Now I know that the signal is created by the sensor not by the pcm.

[@insaini87]

My downstream 02 sensor voltage using my scan tool jumps up and down after 5 min of warm up. Bad sensor?

[@metalpolishshop]

Not necessarily a bad sensor. Is your upstream O2 sensor working correctly ( voltage swinging up and down fast) is your catalytic converter working and causing a rich fuel mixture to hit the downstream sensor

[@nimtabile9198]

Found this video diagnosing a P1135 fault code on my OBD II( 2003 toyota camry 2.4l). I started out by replacing my catalytic converter and the upstream (bank 1, sensor 1) I already replaced it but the code still persists.

[@dennisyuen3986]

I think that certain time you are refering to is 0ne second. since most obd2 oxygen sensor now has heater ciruit element built in. you can identify them by the pair of either black or white wires. Not just WHITE.

[@etripp111]

All in all still a good video. ;-)

[@crockett159]

Videos are cool. Much respect. If you're in California I wanna pay you to teach me in one day how to diagnose and repair ac system

[@hookerallison1]

Can u receive good continuity and not get close to 1 volt?

[@lornaz1975]

So does the sensor itself produce voltage when it gets hot? When testing it did not seem that you added voltage but only checked what was coming from the sensor.

[@williammason1932]

This is also my question

[@lornaz1975]

@@williammason1932 I later found out that it does. The channel listed below has a very good vid on it: kzbin.infovideos

[@samwilliamson1732]

He does state a couple times that the sensor does generate the voltage. The voltage is what the computer is looking at to determine how rich or lean the fuel:air ratio needs to be. The sensor produces the voltage.

[@sarghanat]

I changed the down stream 02 Sensor on a 2002 Elantra for code P0038, no effect !!! Any suggestions please The car barely drives.

[@blackbirdpie217]

The downstream sensor won't really affect how the engine runs, it's just there to see if the cat is working. It's kind of useless that way because it should never see mixture since the cat's supposed to clean it up.

[@lightseek88]

Hey bro, do you stay in san diego cuz i have a 04 vw gti thats giving me a random misfire code p0300 and was wondering if you can take a look at it and maybe make a video using the car on diagnosing this code, im not rerally sure how to get ahold of you maybe just respond to this comment and well go from there if its something you can help me out with, thanks.

[@TargaWheels]

So this test applies to 1, 2, 3, and 4 wire sensors? And does the speed of the voltage rise and drop determine if a sensor is bad or not? Also, is there one common thing that show up with a bad sensor, like not reaching a certain voltage, or going from hot-to-cold-to-hot too slow, etc.? Thanks.

[@vicky-nc3to]

In a car the wires for upstream CC are. 1. pump current 2. sensor voltage negative 3. heater negative 4. heater positive 5. compensating current 6. Lambda control, Can you explain what is the use of so many wire. why not only 2 or 3 ?

[@justinbacile8535]

vicky singh

[@aimansahaja5981]

which pins did you poke while flaming the sensor? and is it on Vac or DC

[@jakejones5736]

DC for SURE.

[@dynamn]

Does this require to be cleaned at regular interval as the mass air flow sensor please?

[@Paiadakine]

dynamn no. Either they work or they don’t.

[@bradlfsh]

Quite intuitive frfr. So if it ever goes out of the .1-1.0v range then that's also a sign it's no good ?

[@songsfromthelord888]

Thanks Ratchets, very helpful thanks again! 🙂 Remember that God loves ❤️ you!

[@Ilovetosingem]

Hi There. Great video. I'm also interested at this moment about cold engine and hesitation when good idle but then increasing RPM which makes it go rough. As I understand it, the O2's, FPR and EGR have no input until they reach operating conditions. Also how should downstream O2's behave as mine is 290mV generally. If it needs to be high say 900mV then could I make a potential divider and produce the 900mV to see if it ineed makes a difference. I don't know what current would be needed yet in order to make the devider. I had a 1131code swirl valve and when I cleared it as I needed to for the MOT it went as above. Also now and before, it went slow up hills and hesitates. Thanks a lot for any info.

[@sizzelot]

So when he heats the sensor is it actually creating voltage or does the circuit lower resistance so the multimeter can push the voltage through? Could you also do this test with the multimeter set to measure ohms?

[@sizzelot]

On a 2012 Acura TSX 2.4L with the old upstream O2 sensor (2 black wires, 1 blue wire, 1 white wire) still installed in the exhaust I tested the resistance between the blue and white wires with the engine off and while the engine was running. Both conditions showed infinite resistance (open loop) which I believe indicates it was bad and was the reason I was getting a P0420 check engine light. When I installed the new O2 sensor there was infinite resistance with the engine off and showed a small decrease in resistance with the engine running with higher decreases as the rpms increased. When I tested for voltage I got no indications.

[@autologista]

excellent

[@EngineerDZ]

Can the touch be used to clean the Oxygen sensor?

[@eventdepot2308]

Hi Imma getting 1.4 ohms or 14ohms..... then voltage is 1volt when temp gun sez 260++ all the way to 585 F is that okay? help peeps.... I applied 12v on the heater and it heated to about 40 to 60 that okay?

[@BulliKid]

So was that sensor good?

[@Aladinscave]

Correct me if I'm wrong but a o2 sensor do NOT measure the o2 content it simply heats up witch changes the amount of voltage going to the ECU, witch will determine how much feul goes into the system ......

[@garagescrapalrowadalrowad8184]

Thanks a lot

[@tomashernandez3016]

I recently got a new ECU installed and after a few months I got a check engine light with the p0420 code and I was wondering if it has something to do with the o2 sensor or more to do with the catalytic converter? I own a 2015 lancer.

[@mikeymagic117]

Sorry to say this but 9/10 it is the Catalytic Convertor. You could try CataClean.

[@mikeymagic117]

2015 is fairly new to be having problems with the Cat unless you have been driving car continually with a misfire which will fry your Cat.