O2 Sensor Test - How to check to see if your aftermarket O2 sensor is bad

[Philscbx]

What a Great RealTime Test.

Thanks

[rockinw401]

Would an sti o2 sensor add horses to my 2.5i?

[AEMonly]

No, but it will tell you if your tune is safe or not...

[nialljamesbuckley]

Great video, even greater last name

[218Minesnowta]

i have a 97 eagle talon and the a/f gauge is stuck on rich. so what does that mean?

[AEMonly]

@218Minesnowta Your sensor has most likely died :-(

[BlackFreemasonsSuck]

@AEMonly I* just got a new EGR valve because the scanner was reading po401 causing my check engine light to stay on. A mechanic told me I needed a oxygen sencor, what do you think about that?

[Jskrapper]

Great vid. When the sensor goes bad, does it typically read rich or lean? Probably neither, but I was just wondering if there was a more common failure. My car was away all winter and now the uego is reading very lean with no changes to the car after I brought it out. Egt's are still right on key so all signs point to the sensor.

[AEMonly]

@Jskrapper It can go either way, although our experience it usually fails to "rich".

[thyaaawad]

i have a bad o2 sensor with this car i just bought but it has an air/fuel mixture and its all the way clockwise but the light is green, does that make any sense at all?

[thegamefgunit]

I did this test, but instead off staying at 10.0 or going back to full lean it was bouncing between 10.0-10.2 and ---. Also my sensor takes nearly twice as long to warm up and go full lean as both the sensors in your test.

[TheGarrettt04e]

hey guys. anything other then break cleaner that we can use for this test?

[MegaXcookiemonsterX]

@TheGarrettt04e your can youe carb and choke cleaner or starter fluid id guess.....there all flamable

[internap627]

thanks, i think i'll do this before buying a new one.

[b20efrt]

Is there any way I can just buy the gauge part I just bought an Evo and I'm missing some of the pixels for the numbers and dint want to replace the whole wideband...

[AEMonly]

@b20efrt Sorry, AEM doesn't sell just the gauge. You can send it back in and get it repaired though. Call AEM at 310-484-2322 and talk to tech support, it may be cheaper to buy a new gauge, but it may only cost about $100 to have it repaired.

[israel160982]

can i test a sensor with a multimeter to check the voltage also with the same fluid?

[AEMonly]

@israel160982 Yup! In fact, you can use a multimeter to watch the voltage on a stock sensor.

[spelunkerd]

I'm guessing the gauge is reading voltage. Can you tell me the voltage output you expect from a good sensor in various conditions? I have an oscilloscope but not a dedicated tester like this....

[AEMonly]

@spelunkerd Check the instructions for the gauge and there's a chart in there for voltage to AFR you can reference.

[greasemonkeypol]

geia sou re papadaki wraios

[pirates860]

it funny cuz mine is stuck on 14.7 as of last light, aem will be getting a call on monday after i check the wiring

[jasmenter]

wraios o mr papadakis !!!

Nice video mate !!!

[bikr1975]

just curious, if the motor is going to run lean, is the voltage higher or lower on the o2 sensor?? how can you fool the computer into thinking its running a little too rich so the computer would send less fuel to the engine? please help me witjh this question. thanks.

[AEMonly]

@bikr1975 You don't want to fool or "spoof" the O2 sensor going to the engine. You will want to tune the engine to run in the range you want it to run.

[twistymcslide]

i need to express my pleasure with dealing with your reps today AEM . oddly , brand new out the box i had a bad sensor , wouldnt heat . and would barely meter( idle 19+afr when it was rich enought to run a car off the fumes , would meter up to 13afr, nothing above) . anyways, did this test today and felt it not working, called, and dealt with ed and a nice young lady who were very helpfull and polite and knowledgable. just wanted to say thanks for the help. will buy more and tell customers.

[AEMonly]

@twistymcslide Thank you for the kind words!

[scintil]

Thanks for the video!

[NagatoTheSeventhPain]

hey thanks for the tip! awesome video!!

[Lotum4n]

Wouldn't a OBD test tell you if the O2 Sensor is bad this way you dont need to buy the sensor tester ?

Thanks in Advance .

: Tim

[AEMonly]

@Lotum4n Only on a stock sensor, which a wideband gauge won't be reading from anyway. This test is to see if your aftermarket wideband sensor is bad.

[quadcartel]

Steph would make a good sham wow sales man replacement.

[Nsanitysince89]

where can i buy that tool/equipment?

[MoncefFaik]

Love AEM products.

[slingblade1991]

So maybe its only my sensor malfunctioning when it says 17.0 at WOT in my car....lol

[jcb1972]

Where can I get a tester like that?

[krazy8tattoos]

ive got a sunpro afr gauge and after installing it it stayed at lean didnt sway then i put 2 new O2 sensors in and now instead of 1 main led lit it goes up to 2 ive had it in the orange range barely lit never reaches ideal mixture nor does it sway when throttle is peaked any suggestions as to why it stays to lean? i have a ford zx2

[LensterOne]

Can you do this test on a heated O2 sensor like the Bosch Wideband Sensors or will the heat catch the brake cleaner on fire?

[telinusawell]

what is the best sensor for improved reading wideband AEM WIDEBAND

[Super98mustang]

Will a bad 02 Sensor cause a car to stall at idle, have a rough idle, and bad throttle response? Please Answer!!!!!!!

[tscompusa]

@Super98mustang if the car uses wideband o2 sensor OEM like some bmw's and cadillacs etc, then yes it will. if its just a regular o2 sensor youre using to sniff wideband signal on a vehicle that uses narrowband for closed loop operation then no it will not.

[Turbotrips]

Hi, I use a analogue voltmeter to test the sensor. I have a question, when the sensor is out in the open air, it creates a negative voltage of about 0,1 volt. Is the sensor bad? It work fine with the rag and some flammable liquid in..

[fgbaz]

This bit of kit you are using: can i buy it ? if so how do i go about buying the kit, i am a toyota technician in the UK, looking for bench test equipment to test 02 sensors.

[ozmedia]

@fgbaz You can do it without the tester with a multimeter and a propane torch (or with the shop's the Oxyacetylene torch if you are careful). I've been doing it for years as a back up to a scanner graphing the running voltage (oscilliscope to watch frequency and switching voltage). There's a youtube video on it but they don't let link posting in comments now.Search "Auto Repair: Oxygen Sensors - Testing and Replacing (1 of 2)"

[aznpholife]

I might have this problem, if I do...is there warranty to cover this, like a replacement?

[two4rider]

my wide band worked great for 4 months reading exactly what i am commanding at WOT. last few weeks at WOT it drops to 11.9 - 12.1 area when the dyno sniffer indicates 12.8-12.9. i first noticed it going odd a few weeks ago when it would hit 12.5 at wot, and it seems to get progressively worse. any idea?

[two4rider]

my wide band worked great for 4 months reading exactly what i am commanding at WOT. last few weeks at WOT it drops to 11.9 - 12.1 area when the dyno sniffer indicates 12.8-12.9. i first noticed it going odd a few weeks ago when it would hit 12.5 at wot, and it seems to get progressively worse. any idea?

[tdog4500]

very nice was lookn for a way to check my wideband for accuracy, my pc shows im rich when my wideband goes way lean, assbackwards for some reason! it will actually even throw the ses light saying rich when it goes lean on the aem gauge and its only a few weeks in use

[IXEvOIX]

my sensor is stuck on 14.8 why?

[AEMonly]

@IXEvOIX Check to make sure your sensor is plugged in all the way, if it is then it's maybe time for a replacement.

[IXEvOIX]

@AEMonly now this will throw you for a loop ive replaced the sensor still nothing changed i tried 2 other gauges still nothing and i even tried different wires, nothin so pretty much ive tried 2 or 3 different sets of wideband all aem and still nothing has changed and no one in my area can seem to figure out why.

[AEMonly]

@IXEvOIX Very odd indeed! Where is the sensor mounted? You've checked/replaced all the wiring (both to the sensor and for power), correct? What fuel are you running? I'm assuming it's in an EVO, correct? More info the better to try and solve this.

[IXEvOIX]

@AEMonly no it is an srt-4 now, and as for the gauge it mounted right next to the stock boost gauge and for the 02 sensor it was on a custom bung that i had put in but its in the same spot just about every other down pipe has for wideband, no i have not ran any race gas since its been in just normal 94 pump gas yes iver replaced the sensor wire and nothing changed

[IXEvOIX]

@AEMonly as for power i didnt because its just power growned and datalog if im not mistaken and ive tapped into different places to see if it was a power issue but nothing changed, the gauge worked for the first hr it was on my car and was flawless then i turned the car off and it hasnt worked since then.

[twistymcslide]

@AEMonly did you all ever solve this ....

[chrise213]

dude your a F cken true mechanic. i have been having trouble with an my O2 sensor and your test is what I needed to see. i am having error p0174. due they sell that tester.

[mediarocker543]

@chrise213, IIRC its hooked up to a mockup computer, which gives the meter its reading... It looks like he has a benched AF system.

[demotorduvel]

Thanx for the video mate, besides the sensor test, this makes a nice "how it works" video, clears things right up.

[cattcomp]

qqye values would have to make a AEM wideband running on a turbocharged engine running with metahnol

[veedabestchef]

is 02 sensor stands for oxygen sensor

just making sure..

[cattcomp]

AEM 30-4100 can be used to fuel 100 % metahnol what indicates running metahnol AFR / LABDA  ?thank you very much

[CadetLD]

@veedabestchef

yes its o2 or oxygent

[CadetLD]

@veedabestchef

oxygen*

[217zenki]

yes

[shine1221]

i have a p0420 and a p0301 just changed the plugs cause of that code but still there.damn i waste gas like crazy in my 1998 cadillac deville im getting sprk to the plug everybody says to change the cat but i dont hear any rattaling in the cat like its bad HELP HELP HELP

[maxestuardo]

BAD SENSOR.. bad sensor

[AEMonly]

Bad, naughty sensor....

[garcon98]

you can use a propane torch and when hot volt will increase and as it cools within 3 seconds should drop that works also ,,,,good video helpfull :-)))))

[07rylin]

how can i purchase the tester you are using and do they make a tester for the heater circuit

[AEMonly]

Go to AEMonly (dot) com and buy any UEGO Wideband Gauge.

[Duckyistrippin]

does this test work for the OLD external uego with no display? {if i monitor through the ems} the one i have now bench test open air high 16's, gas on a rag 14's. Yet when i drive and tune, i see afr's lower than 14. what gives? bad box? bad uego? bad sensor?

[AEMonly]

Sounds like your sensor is starting to go bad.

[axelstrife]

no what i meant was makin a gauge and sensor fittings etc.the towel and brake cleaner is easy part. i meant makin a jig

[AEMonly]

@axelstrife , You'd need power to the gauge and sensor. This is for an AEM sesnor, not a set up for stock sensors. Each sensor read differently, so you'd need to know the range of voltage the sensor sends normally and monitor that, perhaps with a multimeter?

[trunkz007]

i wanna make a jig like in this vid.how do i make one?

[AEMonly]

A shop towel and a can of brake cleaner.

[detenionboy101]

which sensor is bad when your car begins to buck at high way speeds?

[86rockyjt]

is there other ways of telling it bad on the car

[AEMonly]

If the gauge reads " - - - ", the sensor has gone bad.

[newmanto03]

k , but can you tell me how a bad oxygen sensor would affect your cars performance?

[AEMonly]

Depending on your tune (if you are running O2 feedback or not and how that is set up), the car may run rich (or lean, depending on the voltage the bad sensor is sending). This is why it's key to monitor your Air/Fuel on a modified vehicle.

[meatdept]

@AEMonly when my car idles it bounces from 1k-2k, does that mean that my O2 sensor is bad also?

[AEMonly]

What kind of engine management do you have?

[meatdept]

@AEMonly well i have a 93 civic hatch with a single cam ZC, and its running on a p28

[AEMonly]

You are running a stock (or stock replacement) O2 sensor?

[meatdept]

stock O2 sensor

[AEMonly]

it will probably run rich, causing you to get worse MPG.

[engled2000]

Great video, saved me a ton of time today.

[AEMonly]

:-)

[ratheads]

Help ! I run 110 leaded octane in my sandrail, how do I get around ruining the sensor ?

[AEMonly]

Most will say no matter whose wideband you are using, when you switch to leaded fuel, you have a limited amount of time until the sensor dies. In our experience on 3 different race cars, we have had the sensors last an entire season. We don't think it's our sensor but the tune on the cars that makes the difference.

[ratheads]

Thanks a bunch, that helps a lot !

[SediciTurbo]

Excelent !!!!! thanxs.

[saturbo1107]

Woow just what i was looking for!!! thanxs so much for this video!!! I'm reading no activity on one of the o2s with the scaner, now i will runn this test!!!

[Hebert6760]

So the lower the numbers the richer and the highest the leanner??

so i'll want my car to run with lower nunbers right?

[KesAFCA]

you get the most performance out 12.5 afr and the most gas milage out of 14.5 or so, but this varies from car to car..

[AEMonly]

KesAFCA has a good rule of thumb, but be careful though, as running even a little lean can cause damage. Also, EGTs can play a part in tuning, some turbo cars are happier a little richer to cool the combustion chamber.

[workensmart]

thanks this was just what I was looking for. But I would like to know one thing. for an early OBD2 car (96 Bonneville SSEI) should I change just the post 02 sensor or both when doing a tune up?. the car has 104K miles.

[almarai185]

what is the benefit of Dual wideband sensor ?

[AEMonly]

If you have a V6, V8 or a "boxster" style engine line the Subarus you can monitor the air/fuel in each "bank" of cylinders. For most cars though, one O2 sensor is enough to keep tabs on your mixture.

[Pyper70]

I have a 69 Charger and I want to check the left and right banks for the air/fuel ratio. Can I get two λ sensors and hook them up into a harness and have them wired to an A/B switch in series to the air/fuel gauge? Pop the switch to the left and read the left bank, middle is off, right is right bank. I notice that some A/F gauges need to run down a 15 second diagnostic or "heat up" period. Will I damage something if I run a 3-pole switch?

Thanks for the video. I am also a "Dakis"...Crete?

[AEMonly]

Seems like a neat idea, but the sensors have 4 wires that enter the contoller not just one.

Best is to run one gauge/ sensor on the leaner bank or seperate gauges for each bank.

Yes Crete :)

[Eraab212]

so technically u can do this with any 02 sensor and if u dont have a gauge use a multimeter and check to see the volts going from full lean(.5v) to rich(0v) while using the rag and brake cleaner?

[AEMonly]

In theory is should work, but we can't comment on all the different brands of O2 sensors (but the AEM uses a Bosch sensor, so it should work the same on all Bosch wideband sensors).

[Eraab212]

cool. I actually tried in tonight and my freind was running the same wideband the we use on his mustang using BIG STUFF. Having another problem and posted on the AEM forums under mitsubishi evolution if u could direct someone there.

[customize44]

Interesting, every OEM OBD2 oxygen sensor reads 0-.5v (0v being lean, and .5v being rich).

[frogvillage]

how about when you test it with multimeter what do you need to see?

[AEMonly]

If you have an AEM UEGO, the voltage on the white wire sweeps from 0-5 volts (10:1 "rich" is 0 volts, 19.98:1 "lean" is 5 volts). So you will see 19.98 volts when the sensor rolls over to full rich.

[toniob18b]

it is the same manner for Innovate

[AEMonly]

It should be the same, but we don't have an Innovate here to test.

[xxstuntin23]

where can u buy that tool

[AEMonly]

Which tool, the rag, the brake cleaner or Stephan? ;-)

There is no tool to use, if you have a AEM UEGO (or any aftermarket wideband) you can do the same test with just the rag and the brake cleaner.

[AEMonly]

If it was the Bosch sensor AEM uses we could help you out, sorry!

[dontcare3426]

Is there any way to do this same test with a digital meter?

[AEMonly]

Sure, hook up the test meter and watch for a sweep of voltage from 0-5 volts. Full rich is 0 volts, full lean is 5 volts.

[light4darkness]

Not to burst your bubble, but doesn't your wide band use an atmospheric air reference? Zirconia sensors need one.

So when you snuff out the oxygen with your wet rag, if you are covering both the exhaust side, and the athmospheric reference side of the sensor, you cannot expect accuracy.

Maybe the first sensor is not bad. Leave the outside fresh air holes uncovered by your rag, and see if it still goes lean.

The second sensor may have a better air pocket for reference voltage.

[AEMonly]

No bubbles burst! You are correct, this type of sensor needs to see atmosphere, and while we don't make it clear in the video, the part of the sensor that needs to be outside the towel is in the strain relief at the top of the sensor (corrugated plastic part) and is seeing atmosphere while we are testing these sensors. The first sensor is bad, as it is outside the towel (0:39 seconds into the video and not near the brake clean).

[erickrm]

Hi there, wondering if this will happen only when at WOT? my sensor reads while idle and while norm driving, but when i go wot it will hit full rich! and then after a bit it goes full lean.... so im thinking bad sensor as my logs dont show any other bad readings besides the AEM02sensor but curious why it would work fine while normal driving.... anyways to reset the unit?

Thanks.

[AEMonly]

Since it goes full lean, it sounds like your sensor is bad. It's not uncommon for cars to run "rich" (in most street cars this is around 12:1) at WOT, but it should not go full rich on this gauge.

[jbreu2]

with this gauge how do u read it to know that theres something wrong with ur car with the air/fuel things ( rich and lean)

[AEMonly]

The lower the number, the richer the mixture, the higher the number, the leaner. On a N/A car at WOT you'll want to see around 13:1, on a boosted car, you'll want a number closer to 11:1, but it depends on how much boost you are running the most boost you are running the richer you'll want to be).

[jbreu2]

oh yea thanks bud :)

[fastcarkid24]

my talon said its air/fuel is at 14 and some times around 20...and the car bogs ans back fires alot whats wrong?

[AEMonly]

Sounds like you are running too lean. Who tuned the car?

[AEMonly]

Make sure you are using a small enough screw driver, so look and make sure that it is actually turning he switch. Don't turn it too hard or you can break the switch, if it just turns and turns and never stops, that switch is broken.

[Valejola]

There is someone that know how can i change the output voltage from P0 to P4?

I try to turn the rotate switch behind the gauge but it has not happened anything :(

Please, halp me!

[3800GTV6]

Damn thats crazy, been wondering if my wideband has been working properly or not!!!

[yamiboost]

Great vid thanks

[06scapex]

Even after warm up mine wont go fully lean in open air is my sensor no good?

[b18cyacrxs]

Does the aem afr gauge come with that plug?

[Valejola]

Sorry but i don't understand very well a english speak word so...wich is the good O2 sensor? The first one or the second?

And what a kind of spray i can use to test it?

Thanks

[AEMonly]

First is the bad sensor. It does not stay "rich"

We use brake cleaner to test

[jayvicious]

the first one is the BAD one, the second one is the GOOD one

[turbodx]

WOW thanks man , beats sending it in to AEM to have them check it , Thanks again bro

[richzap]

Very Cool, helped me out a lot thank you.

[nwo2go]

Great info. Thanks!