Oxygen Sensor - Explained

[@r42221]

I love it when you have multiple questions in your head, and then the presenter answers all of them without you even having to ask! GREAT VIDEO!! Much respect from a fellow engineer (mechanical). Now, it's time to replace my MAF and O2 sensor on my 2005 Volvo XC90 which has 317,000 miles!

[@dimhal7840]

youre a mechanical engineer but you dont how a λ sensor works?

[@jwo7777777]

Closed loop = measurements from the system output (in this case the oxygen content of the exhaust) are used to modify future control values (fuel/air mixture ratios). Open loop = control values (fuel/air ratios) determined solely by measurements from system input (map sensor, throttle position) and system model (limp-home basic fuel/air mixture ratios stored in the ECU).

[@gregkimura5906]

I love watching your videos. I'm an electrical engineer and your videos describe the operation of vehicle systems in detail, but in layman's terms for the average person. Great job, keep up the good work!

[@EngineeringExplained]

Same initial four strokes plus an additional stroke injecting water used to take back some of the lost energy and make it useable (vaporizes and expands), and then an additional exhaust stroke. Basically done to improve efficiency and reduce emissions. Fuel is injected once every 3 rotations of the crank rather than every 2 rotations.

[@EngineeringExplained]

Quite a few codes... I don't know about the fuel banks, could be a lack of fuel going to the cylinders. I'd check the spark plugs, if it's run with a distributor check that, the rotor and cap, as well as making sure the wires are fine. If you're not getting a spark it can throw off a few codes, so I'd start looking at that - only a guess though.

[@EngineeringExplained]

Perhaps eventually, comes down to many things. The weight of the cars, friction of any rotational components as well as friction via the tires, rotational inertia, engine size and efficiency. Many of my "how to increase horsepower" videos actually apply the same ideas.

[@EngineeringExplained]

According to wiki: "This sensor eliminates the lean-rich cycling inherent in narrow-band sensors, allowing the control unit to adjust the fuel delivery and ignition timing of the engine much more rapidly."

[@garyvanremortel5218]

Not a voltage spike. Once heated to 600deg it outputs a constant voltage varying directly as Oxygen concentration in the exhaust gases.

[@gojudude]

The rear sensor actually responds faster as a rule. The reason it reads lower is due to the gas concentrations and the overall gas exchange time not the intrinsic sensor response time. The rear sensor is protected by the catalytic converter, so it sees less contamination from the exhaust gas and therefore less degradation. Remember that the front and rear sensors are operating under different gas conditions, so you will see different responses independent of the sensors themselves

[@EngineeringExplained]

Yes, coming soon!

[@EngineeringExplained]

Could be, though I believe it should throw a code (CEL) if it's bad.

[@catamarii]

this series is literally saving my life right now !!!!!!! thank you

[@carlthomas4451]

I like the way you explain!! New subscriber!!!!

[@EngineeringExplained]

Thanks!

[@EngineeringExplained]

You can still tune the A/F, and most don't work when you're at WOT to allow for rich mixtures.

[@EngineeringExplained]

Your written English is fine; maybe one day I'll work on captions.

[@firesteako]

Just a random question. Do you play Street Legal Racing:Redline? It's really fun and most of the stuff you talk about actually helped me build my first car! :D

[@jwo7777777]

The "narrowband" (2, 3, 4 wire) sensors only report that the mixture is lean or rich. The "wideband" O2 sensors (5~6 wire) give an indication of how lean or how rich. So a control system using a wideband sensor can correct back to ideal fuel/air ratio more rapidly and with less error. Lookup "AFR sensor" on wikipedia for more info.

[@Kmullins131]

My favorite series from you!

[@ZeroalphaAu]

What voltage = 14.7:1? Do I assume 0.45V is stoich AFR? If this is the case does 0.1V = 3.3:1 and 0.9V = 29.4:1?

[@DENicholsAutoBravado]

Oh definitely not. You know how AFR are considered wide band? They can see a much wider range of air to fuel ratios. An oxygen sensor can barely see above and below 14.7:1 so the goal on a car with a front o2 sensor is to go up and down passed ideal. You definitely can't infer AFR like you'd get off an AFR sensor to the voltage on an o2 sensor.

[@EngineeringExplained]

I believe so, unless they have no emissions requirements, then they may not.

[@hmata3]

Misfires can lead to rich exhaust gases, causing clogged cat converters, then other issues regarding fuel/air ratios. You may have individual coils, since it is a Ford V-8. Try to switch those on cyl 2 & 8 with any other. Then clear the present codes and drive for at least ten miles for newcodes to appear. This will then give u an indicator of what components u may need to replace, i.g. coils, spark plugs, o2 sensors.

[@dstny09]

Great videos. The only thing I don't get is why the 2nd sensor usually reads a lower voltage than the 1st one. (some oxygen ions from NO are reduced to oxygens, but oxygens are also used to oxidize CO and CxHx, why is the net difference usually positive?)

[@nolimitfaze0123]

man just explained this so simple and perfect i love em

[@bellamelissa87]

So if my car is having a failed o2 sensor on sensor #2 and the check engine is also reading a catalytic converter I may just need to have that o2 censor changed? Could the o2 sensor be causing a back flow of oxygen? Sorry if that's not clear ha ha I wish I had more knowledge on cars.

[@EngineeringExplained]

It could just be the sensor, yes.

[@ZGoughy69]

hey man. long time viewer. can you explain fuel trim in regards to o2 sensors

[@gunnardavid8427]

Pro trick : you can watch series at Flixzone. Been using them for watching loads of movies during the lockdown.

[@juancorey4138]

@Gunnar David yup, I've been using Flixzone for years myself :)

[@sinsagoodmansbrother]

Excellent presentation... You are a smart young man... Thanks for explaining to this 64 year old... I just had my Jeep Liberty throw out a code for this...

[@EngineeringExplained]

Sure, but oxygen on it's own is fairly dangerous, hence people use N2O since it's a bit more safe and can provide serious power gains.

[@danievanderberg]

can you upload a video explaining the mechanics behind stalling? Would be a great addition! You got awesome vids!!

[@TheOxyMorin]

Can you make a more in-depth o2 sensor video? 3-wire, 4-wire, wide-band to a gauge in the passenger compartment, etc.?

[@ralliartstyle]

Can you explain wide band 02 sensors and the pro's and cons? I'm tuning my evo and can't find any reluctant info on them.

[@ralliartstyle]

Relevant *

[@EngineeringExplained]

It's checking the efficiency of the cat, rather than using it for altering the A/F ratio (sensor after the cat).

[@whitestar279]

I think you should put a real thumb nail of the part or system you are talking about. i believe it would attract a lot of new viewers. just my 2 cents :). love your vids btw ! you make me look smart in mechanics class :P

[@Kmullins131]

Could you do a series on bridges?

[@fastodie]

How would you extended the wire s on those sensors? Because I installed headers on my truck and I want it to read right before the cat but it doesnt reach all the way . So I had to put it on the right header.

[@zhichuenbbq]

keep up the good work mate, really enjoy your vids!

[@crystrezerex2life]

Nice vid....what should the post oxygen sensor read?

[@NoferTrunions]

Why does the upstream binary sensor switch? Is the mixture "switching" or is the switching some kind of binary method to determine the steady state (non-switching) exhaust O2 content?

[@danielmacsay8364]

So does the 0420 and 0430 codes always mean bad converters and how can you narrow it down further before throwing a couple grand at it with new OEM converters?

[@shortfuse1993]

so for curiosity sake if you have a car that is set rich and has a computer that's locked (IE: Dodge) would getting wideband O2 sensors and MAF sensors increase the ability to tune the A/F mix?

[@phongtrinhxuan]

why the oxygen sensor signal looks like a sine shape. Rich and lean while engine operates. thank

[@noel1553]

I figured it out, it was an installation error on my intake gaskets. I took everything apart and slapped in some new ones. My air/fuel ratio problem is solved. She's still a little shaky but I think once I get the new spark plugs she'll be running good again.

[@mattanfang]

Would it be possible if I would block off my secondary O2 sensor? My car is old and I get engine oil blow-by occasionally. I do not have emission standards to pass and just have an annoying CEL light. I am thinking of using 2 defoulers with some stainless in between to block the occasional oil coming out of it. I'll still have the sensor installed but just basically completely out of the exhaust flow. What do you think and thanks for your time.

[@torijenna1629]

Does the ECU adjust air fuel ratio, based on the sensor after the Cat ? In performance exhaust applications many times the cat is omitted or high flow. So one will use a defouler or some how program out that sensor on the ECU. Will this cause the ECU to not make adjustments appropriately. Or is the ECU primarily checking the efficiency of the CAT? Thanks for your time!

[@baseballrockssb]

Can you do a video on what makes better fuel economy like cars with 30mpg vs a car with like 40-50mpg. I'm not talking about hybrids vs regular cars or a regular car vs an SUV cuz there are obvious reasons for a difference in fuel economy. I'm talking about like comparing normal 5 seater cars and explaining why there is a difference of 10mpg. Thks! :)

[@ishmale89]

thanks for your easy to explain video... I have a question though, if there is a fault in that 1st sensor, could it cause issues for the second... I have a fault reading on both but after tests the mechanic thinks it's just the first that's faulty... could the fault in the rear sensor be as a result of the faulty front sensor and it's effect on fuel ratio??? I.e. get the first sensor replaced, better fuel ratio and better readings after the cat? thanks for your help

[@RealDeanWinchester]

I need to set air/fuel ratio on a propane fueled engine. I was thinking about using a "lambda" sensor or a wideband O2 sensor, will they respond correctly on a propane engine? I understand the stoichiometric ratio is different for propane, but will those instrument correctly indicate AFR?

[@3-E]

can you do one on how various mufflers work and the pros & cons of each type?

[@EngineeringExplained]

Perhaps in time, basics for now.

[@peacemoulders958]

This is engineering made simple. Thank you so much

[@arefmoughraby9756]

hello mrs super engineer thank u for all of ur videos they are amazing i want to ask u if u san do a video about ecu and if want how do the ecu know at which time it will ignite the spark in the cylinder and at wich time it will be a full compresion of the a/f mixture i appretiate if u answer and thank u again for ur videos

[@modularperformanceracing1799]

Is it better to have catalic converter or not? And will increase or decrease performance? Thanks

[@SJ-im9kt]

Do all exhaust systems come with o2 sensors? Looking to get a new exhaust system.

[@SpiderWebUntangled]

Very few secondary O2 sensor also report closed loop rich lean info back to the PCM, not only Cat Efficiency data, it is rare. A good Cat will use up the STORED O2 in the substrate so very little O2 comes out of the Cat so the constant reading can be a low or high voltage as long as it does not swing is the important thing to know. If the Cat is burning the stored O2, the secondary O2 sensor will report rich or lack of O2 which is fine. There are also arguements if this sensor actually reads O2.

[@spelunkerd]

What surprised me about this system is that the cat works better if the proximal system bounces between rich and lean, providing CO and other compounds to help the Cat do it's job. When I first studied this system I thought it would tend to keep numbers in a narrow band, but you actually want some wide fluctuations to provide substrate for the cat.

[@rashiraja5097]

hi , im enigne prof for CAT , ur explanation is great , although addition of some animations will be great

[@XHikotheproX]

So if i get a handheld tuner for my car, what air/fuel ratio would you recommend i set it at, assuming you can change it. If im looking for more performance. I would think richer than 14.7:1. Maybe like 13:1?

[@my-kecontent8488]

I like the way you explained. I just wanna ask, why does a bad o2 sensor can sause an entire bank to misfire?

[@RickVicious41]

Actually taught me a lot. Thank you so much 🙏

[@02SVTFast]

I've been running without any o2 sensors for about 2 years now and my car stutters in the lower rpm's and backfires like crazy when I let off the gas so I think it is running rich and gas is igniting in the exhaust which gives it the crazy backfire.

[@thothheartmaat2833]

so it spikes back and forth between .1 and .9 in the upstream sensors and is it ok if it spikes back and forth between .1 and .5 on the downstream ones? does that mean its got more oxygen so the cat is working? what reading should the rear o2 have? no spiking or less spiking with different readings than upstream?

[@tamingguppies]

Upstream o2 suppose to fluctuates from 0.1 to 0.9 and downstream o2 suppose stay a flatline like 0.4-0.5-0.6

[@briansgalaxynote2]

My S1 is pinging in at 3.+ and my S2 is pinging in at 0.055 P0420. Car runs great though!

[@DrSquib94]

How often does the front o2 sensor tell the ecu to adjust its air fuel ratio? Is it at the same frequency electricity is distributed through the car (just guessing 50 hz like standard US electricity) or is is more like every second or minute or couple min?

[@breakernoah]

You also should have mentioned about wideband O2 sensons which are more responsive and accurate.

[@JohnBrown-ly9md]

Can the rear o2 sensor control the a/f ratio or is it litterally just to check the if the cat is working?

[@imba1986]

Hello just a question. If ever I use a wideband sensor do I still need a narrow band sensor? ex. MTX-1 it has a feature to send analog signal to narrowband.

[@breakernoah]

Correct, they go by various names wideband, lambda, or air/fuel sensors.

[@Bugatti1]

Can you do a vid explaining afterburners on fighter jets?

[@MohamedTarek-qm3vf]

So this is getting a little confusing after watching some other videos. It says that the o2s2 should be on the richer side as the catalytic converters have the ability to store more oxygen but that’s totally opposite from what your saying. Please help clear the confusion

[@dubbullard2699]

I am looking fo buy a 01 Toyota tacoma which has a bad #1 02 sensor, is this expensive to fix, does it affect the truck? Seller says no problem...

[@rtwmediadesign6941]

Can you tell me what a flex pipe is and what part it plays in emissions?

[@AlexPerkinsREI]

you should do a video on bore to stroke ratio and how it effects the engine

[@SproutyPottedPlant]

I must have one of these interesting sensors to play with! I wonder what uses it can have outside of a car?

[@EngineeringExplained]

Glad to accommodate!

[@GeroldAlexander]

After it is removed Can an O2 sensor be cleaned of carbon contamination so it can monitor efficiently and accurately without damaging the permeable membrane?

[@OlaGbolahan]

I'm having an issue with my old truck such that the system ECU is reading like the engine is running rich and adjusting fuel trims negative (LT Fuel Trim = -22) but then i'm getting power drops and stutters like the engine is running too lean. When i hook up the scan tool the o2sensor is oscillating between aprox 23 and 920mv so not an issue with the o2sensor. Any idea what would cause this issue?

[@TheJanope13]

What about how common rail works and how its different to direct injection for diesel?

[@windbreezetv]

I appreciate your uploads

[@mysticalcamo8873]

So by having a o2 sensor you get better mileage? And if that's right how many more miles would you get on the gallon?

[@chakna861]

I have a 1999 Dodge Ram 1500, 5.9L, last year my cat got plugged and had to drill the middle hexcomb out, that saves me about .5-1mpg more by leaving the hole in/on it, i get about 17mpg average and about 18.5Highway when new it was rated at 15average and 17 highway... I get the most fuel efficiency out of it going 45mph. The engine runs more lean/hot though so you'd need a copper additive(leak stop) to a 50/50 engine radiator mix. I got about 10-15° drop in engine temp using aluminum additive(also use whole bottle as instructed or your water pump will leak like a siv).

[@chakna861]

Side note next time at gas station only fill tank 1/2 or 3/4, you save fuel by reducing as much weight as possible. I have lots of junk I keep In my truck, so that 17mpg average could probably get up to 20mpg if I removed it all. Type of tire, Tire pressure, axle differential and steering alignment can also reduce or increase fuel consumption. I use AirTab's to reduce wind drag along entire truck as well, which gives maybe .5mpg and increases maneuverability(turning/lane changes, less wind sheer) and takeoff speed after stoping. Same stuff they place to aircraft wings.

[@navisolim]

Hi nice video! Is it ok if i clean them when they get dirty? I had some problems and after i cleaned them with a metal brush and some cleaning spray the engine chek light didnt come on anymore...sould be ok?

[@DENicholsAutoBravado]

I tried that a couple years ago. The oxygen sensor worked again before it crashed and ran worse than ever. So, if I ever clean one again to get a few more days of function, I'll be immediately ordering a new one!

[@jeeplife7740]

Hi......Can you explain, how the pressure effect the working of Oxygen sensor?

[@gojudude]

A wide band sensor will keep the system in closed loop farther away from stoich. A narrow band (conventional) O2 lambda switch will keep closed loop from 14.6-1 to 14.8-1. The wide band will keep the system in closed loop from ABOUT 10.-1 to 21.-1 The conventional narrow band sensor doesn't know "how" rich or lean, it only knows that it "is" rich or lean.

[@mgayar16]

So what should volt should the o2 show if the afr is at 14.7-1 in closed loop operation

[@EngineeringExplained]

Haven't heard of this game, no. Every now and then I'll play some Forza.

[@MrMattbidz]

wide-band in depth plz for turbo mods to stop leaning out plz?

[@barrymckockiner4887]

Would this be the same as a HEGO sensor?

[@eliasmakwenda1181]

Can a bad O2 sensor cause serious loss of power??hve a toyota altezza 3sge auto,OBDII error codes picked the Oxygen sensor and one mechanic is sayin i should remove the catalytic converters thy r clogged..so im not sure which is which..replace O2 sensors or just decat

[@AirsofterAton]

Can we callibrate the O2 sensor? what if it's not giving accurate data already?

[@mourisegames]

so closeloop mean autotune?? whats about narrow band O2 Sensor, whether narrowband can autotune? keep AFR to optimum

[@patricksweet3875]

The only thing you didn't say is what if both sensors read the same amount of like mine says 0.520 on Each one teach first and second sensors is that good or bad

[@mmcd7591]

I have a truck. Have you heard of 02 extenders? I want to put them on the upper 02 sensors to use less fuel. I also have a minivan with no cat. And want to put the extenders on the lower so I'm not burning rich.

[@toobad9946]

Which condition sets off the CEL? Too Rich, too lean, too much difference between the front sensor and the back or all three? Most vehicle's are fuel injected. How do you change your vehicle's fuel flow to fix the problem? Also, at some point it becomes necessary to replace the catalytic converter. If the fuel flow hasn't been addressed, you will just have to replace it again and again!

[@markco30]

CAN YOU DO A VIDEO ON SHORT TERM AND LONG TERM FUEL TRIM

[@iAerick]

Hi. I have two oxygen sensors, one before the cat, and one after the cat. I also have a decat exhaust setup. So my question is, is it fine for the two oxygen sensors to be reading the same amount of oxygen? Will it confuse my ECU? Thanks in advance!

[@Necrodoxious]

Your 1st o2 sensor is primary and determines your AFR (air/fuel ratio), your secondary sensor monitors the efficiency of your catalytic converter and makes sure that it is doing its job for emissions purposes. The secondary sensor does not affect the readings of your primary o2 sensor, it is merely there as a reading element to determine whether or not your catalytic converter is doing its job correctly.

[@iAerick]

Necrodox ah I see. that makes a lot of sense, thanks! What's the point of monitoring the efficiency of the catalytic converter tho?

[@Necrodoxious]

iAerick 1.) emissions. 2.) to tell you if your catalytic converter is clogged. If it is inefficient something is "wrong" (I only add quotes because some people choose to run without a catalytic converter (like myself), what that problem is can vary. But a catalytic converter is primarily for emissions. It also takes out some of the harmful vapors that you shouldn't inhale.

[@dougla2345]

i recently bought a honda civic that came with a ECU that has been programmed to bypass the oxygen sensors. Ive been having misfiring issues between 1 and 3 thousand rmps. which is really troublesome for me to drive. is this in any way related to the bypassed o2 sonsors.

[@blackbear92201]

Super informative video. Thanks for posting!

[@Yaphets346]

What if i change my exhaust into aftermarket fukl system n have also o2 sensor. Do I need to remap my ecu?

[@FreePalestineFreePalestina]

thank you for the explanation, I was mostly able to follow, but why does it measure voltage?

[@benjaminmcintosh857]

Because that's how electronics work. The sensor detects the oxygen and produces a voltage for the cars computers to read and interpret.

[@Jordy5121_]

@Engineering Explained Well why is when people drive their r56 mini with bad 02 sensors like over period of months they end up burning their cat converter and wash the bores of their engines? seen it far to meany times now on them peugeot engines mini used also

[@pooja-ov7xl]

Can i use this sensor to do college level project? Can i interface this sensor with any microcontroller?

[@mamafratelli3311]

Could you explain why the difference in O2 concentration causes a voltage spike?

[@CO-mp3dw]

The difference in 02 from the inside and outside of the sensor causes oxygen ions to move which creates a voltage. If there’s a big difference in oxygen concentration = Rich Mixture = higher voltage and vice a versa 👌 ... Hope that helps

[@daninavila9375]

great job, saved me lots of time, tks