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checking continuity on an O2 sensor. 05 Chevy Cavalier by jimbolaya
Started on: 07-17-2014 08:54 AM
Replies: 23 (642 views)
Last post by: USFiero on 07-21-2014 10:00 PM
jimbolaya
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Report this Post07-17-2014 08:54 AM Click Here to See the Profile for jimbolayaClick Here to Email jimbolayaSend a Private Message to jimbolayaEdit/Delete MessageReply w/QuoteDirect Link to This Post
I keep getting a P0130 (O2 sensor, engine not in closed loop) occasionally, and a P0171 (excessive lean condition) all the time. The engine light does not stay on. It will come on for awhile and then off for awhile. My research shows that the P0130 probably means a bad O2 sensor. However, the P0171 more likely means a vacuum leak that is causing a lean condition. I can't find a vacuum leak, so I want to test the O2 sensor for continuity, and maybe eliminate it as faulty. This is where I hit a wall. I cannot find what pins, to cross, to check for continuity, and I cannot find what the ohms should read for proper specs. I read somewhere (now I can't find it again) that .1 is lean, and .9 is rich so an O2 sensor should read somewhere between .4 and .6 for proper continuity. Does this sound right? Speak clearly, because electrical stuff is my weakest link. I'm just trying to confirm the O2 sensor is bad before I make my daughter throw $60 at it, and it not solve the issue. I have confirmed 12 volts from the car harness side. That is not the issue. Many thanks.

Jim
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jimbolaya
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Report this Post07-17-2014 08:59 AM Click Here to See the Profile for jimbolayaClick Here to Email jimbolayaSend a Private Message to jimbolayaEdit/Delete MessageReply w/QuoteDirect Link to This Post

jimbolaya

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The 4 wires on the O2 sensor are grey, black, and 2 whites, if that helps.

Jim
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ray b
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Report this Post07-17-2014 09:04 AM Click Here to See the Profile for ray bClick Here to Email ray bSend a Private Message to ray bEdit/Delete MessageReply w/QuoteDirect Link to This Post
12V IS THE HEATER IN THE O2

the 02 outputs a 0.1 to 1 v signal read with a volt meter setting not oms
if 3 or 4 wire the non 12v wires are the ones to test

no idea of oms reading but that may vary with temp
but volts is the good test
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jimbolaya
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Report this Post07-17-2014 09:12 AM Click Here to See the Profile for jimbolayaClick Here to Email jimbolayaSend a Private Message to jimbolayaEdit/Delete MessageReply w/QuoteDirect Link to This Post
I checked ohms on the 2 white wires, which I believe are the heater wires, and got 14.1 ohms. (confuses me even more) I get no readings when crossing any other wires. How can I check volts on the O2 sensor when its not plugged in? I don't think I can. Right now, I am just trying to checking the O2 sensor for continuity to make sure it does, or doesn't have some type of wiring or internal issue. My thought is, if the continuity is correct, then the O2 sensor is working, and my issue lies elsewhere.

Jim
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TK
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Report this Post07-17-2014 11:05 AM Click Here to See the Profile for TKSend a Private Message to TKEdit/Delete MessageReply w/QuoteDirect Link to This Post
You can damage the O2 by measuring the resistance on the sensor wires. The heater at 14 ohms is probably fine.
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jimbolaya
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Report this Post07-17-2014 01:09 PM Click Here to See the Profile for jimbolayaClick Here to Email jimbolayaSend a Private Message to jimbolayaEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by TK:

You can damage the O2 by measuring the resistance on the sensor wires. The heater at 14 ohms is probably fine.


Not challenging you as I do not know much in this area, but there are tons of sites and videos telling me to do the exact opposite. I just couldn't figure out what wires to check resistance on. Oh well, I gave up, and we threw a $60 sensor at it. We'll see what happens.

Jim

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MidEngineManiac
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Report this Post07-17-2014 03:32 PM Click Here to See the Profile for MidEngineManiacSend a Private Message to MidEngineManiacEdit/Delete MessageReply w/QuoteDirect Link to This Post
Trick to try....pull the sensor (lol, if you can and its not welded in by age and heat) and clean the carbon off it....clear your codes and go for a drive and see if they come back. about 1/2 the time in my experience that does the trick......IF you can get the damn thing out....IF........
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jimbolaya
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Report this Post07-17-2014 03:45 PM Click Here to See the Profile for jimbolayaClick Here to Email jimbolayaSend a Private Message to jimbolayaEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by MidEngineManiac:

Trick to try....pull the sensor (lol, if you can and its not welded in by age and heat) and clean the carbon off it....clear your codes and go for a drive and see if they come back. about 1/2 the time in my experience that does the trick......IF you can get the damn thing out....IF........


I already got it out, and a new one in, with plenty of anti seize.

Jim

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jimbolaya
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Report this Post07-17-2014 03:47 PM Click Here to See the Profile for jimbolayaClick Here to Email jimbolayaSend a Private Message to jimbolayaEdit/Delete MessageReply w/QuoteDirect Link to This Post

jimbolaya

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Sorry, double post.

[This message has been edited by jimbolaya (edited 07-17-2014).]

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jimbolaya
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Report this Post07-17-2014 08:23 PM Click Here to See the Profile for jimbolayaClick Here to Email jimbolayaSend a Private Message to jimbolayaEdit/Delete MessageReply w/QuoteDirect Link to This Post
Well the freaking code returned. There's $60 down the drain. I cannot, for the life of me, figure out what is causing this lean condition.

Jim
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Neils88
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Report this Post07-17-2014 11:18 PM Click Here to See the Profile for Neils88Click Here to Email Neils88Send a Private Message to Neils88Edit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by jimbolaya:

Well the freaking code returned. There's $60 down the drain. I cannot, for the life of me, figure out what is causing this lean condition.

Jim


Could be something as simple as a dirty fuel filter. Have you checked fuel pressure? O2 sensor and vacuum leaks are the common cause. Not sure what other sensors a Cavalier has (MAF, MAP, manifold temp etc?)...these can cause lean conditions, but likely those would trigger another code. The new O2 sensor could also be bad...
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Report this Post07-17-2014 11:25 PM Click Here to See the Profile for TKSend a Private Message to TKEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by jimbolaya:


Not challenging you as I do not know much in this area, but there are tons of sites and videos telling me to do the exact opposite. I just couldn't figure out what wires to check resistance on. Oh well, I gave up, and we threw a $60 sensor at it. We'll see what happens.

Jim


No worries. GM has always said don't. You can measure the voltage at the O2 on the sensor side with the ECM supplying the bias but they way they work they can be damaged with some ohmmeters.

Is this a pre or post cat o2? A simple scanner can check them. My son's Z24 started throwing post cat O2 errors when the cat was starting to go.

[This message has been edited by TK (edited 07-17-2014).]

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jimbolaya
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Report this Post07-18-2014 06:39 AM Click Here to See the Profile for jimbolayaClick Here to Email jimbolayaSend a Private Message to jimbolayaEdit/Delete MessageReply w/QuoteDirect Link to This Post
It's a pre cat O2. It's on the exhaust manifold, and the fuel filter has been changed 3 times in the 4 or 5 years we have had the car. I haven't checked fuel pressure though.

Jim
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Report this Post07-18-2014 12:18 PM Click Here to See the Profile for heybjornClick Here to Email heybjornSend a Private Message to heybjornEdit/Delete MessageReply w/QuoteDirect Link to This Post
Time to buy her an Alero, Jim.
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Report this Post07-18-2014 12:48 PM Click Here to See the Profile for TKSend a Private Message to TKEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by jimbolaya:

It's a pre cat O2. It's on the exhaust manifold, and the fuel filter has been changed 3 times in the 4 or 5 years we have had the car. I haven't checked fuel pressure though.

Jim


Ah, ok. I should have known that from the lean code.

I think people have suggested just about everything you can check yourself. Without a scanner to see what is happening it's going to be tough to nail down. You need to check the fuel pressure and mass reading (is it drawing the correct amount of air or getting it from an intake leak or is air getting into the exhaust and causing the O2 to drop.) Get a gauge on the fuel rail and rule that out. Any cheap gauge. Even an AC low side gauge will work in a pinch. Then maybe spray the intake gasket area and large vac lines (booster, etc.) with mass/brake or some other cleaner and watch for a sudden change in the idle or a stumble.

Did you confirm you have 12V at the O2 heater wires?

I sent the manual P0130/P0171 trees and engine control diagrams to your email.

[This message has been edited by TK (edited 07-18-2014).]

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Report this Post07-18-2014 02:34 PM Click Here to See the Profile for Stubby79Send a Private Message to Stubby79Edit/Delete MessageReply w/QuoteDirect Link to This Post
If it hasn't been said, you can check the voltage on the signal wire with it in and disconnected. The car has to be running and up to full running temp. Well, the exhaust does. Even without the heater, it'll generate the .1v to 1v mentioned. Use a digital multimeter, dunno if an analog one would be able to pick it up with such a tiny current being produced. If you get nothing, or it remains really low even when you blip the throttle, it's buggered.
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Report this Post07-18-2014 02:57 PM Click Here to See the Profile for TKSend a Private Message to TKEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Stubby79:

If it hasn't been said, you can check the voltage on the signal wire with it in and disconnected. The car has to be running and up to full running temp. Well, the exhaust does. Even without the heater, it'll generate the .1v to 1v mentioned. Use a digital multimeter, dunno if an analog one would be able to pick it up with such a tiny current being produced. If you get nothing, or it remains really low even when you blip the throttle, it's buggered.


Good point. Even if the mixture in CL is lean the throttle blip with power enrichment should make it spike.
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jimbolaya
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Report this Post07-18-2014 04:50 PM Click Here to See the Profile for jimbolayaClick Here to Email jimbolayaSend a Private Message to jimbolayaEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by TK:


Did you confirm you have 12V at the O2 heater wires?


Yes. Thats the one thing I did know how to do.

 
quote
I sent the manual P0130/P0171 trees and engine control diagrams to your email.



I just checked and received them. Thanks. I haven't had a chance to read through yet.

Jim

[This message has been edited by jimbolaya (edited 07-18-2014).]

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jimbolaya
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Report this Post07-18-2014 04:52 PM Click Here to See the Profile for jimbolayaClick Here to Email jimbolayaSend a Private Message to jimbolayaEdit/Delete MessageReply w/QuoteDirect Link to This Post

jimbolaya

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quote
Originally posted by Stubby79:

If it hasn't been said, you can check the voltage on the signal wire with it in and disconnected. The car has to be running and up to full running temp. Well, the exhaust does. Even without the heater, it'll generate the .1v to 1v mentioned. Use a digital multimeter, dunno if an analog one would be able to pick it up with such a tiny current being produced. If you get nothing, or it remains really low even when you blip the throttle, it's buggered.


This is what I was originally trying to do and no one understood what I was asking. My fault not theirs. I couldn't figure out how to test it while disconnected.

Jim

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jimbolaya
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Report this Post07-18-2014 04:53 PM Click Here to See the Profile for jimbolayaClick Here to Email jimbolayaSend a Private Message to jimbolayaEdit/Delete MessageReply w/QuoteDirect Link to This Post

jimbolaya

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quote
Originally posted by heybjorn:

Time to buy her an Alero, Jim.


A major contributor as always.

Jim

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Report this Post07-18-2014 06:07 PM Click Here to See the Profile for TKSend a Private Message to TKEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by jimbolaya:


I just checked and received them. Thanks. I haven't had a chance to read through yet.

Jim



Maybe they will. Let us know what you find.
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Report this Post07-20-2014 02:14 AM Click Here to See the Profile for USFieroSend a Private Message to USFieroEdit/Delete MessageReply w/QuoteDirect Link to This Post
Lean reading on the O2 in a post cat sensor? Sounds like air getting in the exhaust ahead of the O2 sensor. Could be a leak at the exhaust manifold gasket? Is there a gasket between the manifold and the rest of the exhaust pipe? I'd be looking there.

[This message has been edited by USFiero (edited 07-20-2014).]

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jimbolaya
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Report this Post07-20-2014 06:25 AM Click Here to See the Profile for jimbolayaClick Here to Email jimbolayaSend a Private Message to jimbolayaEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by USFiero:

Lean reading on the O2 in a post cat sensor? Sounds like air getting in the exhaust ahead of the O2 sensor. Could be a leak at the exhaust manifold gasket? Is there a gasket between the manifold and the rest of the exhaust pipe? I'd be looking there.



Pre cat O2 sensor.

Jim

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Report this Post07-21-2014 10:00 PM Click Here to See the Profile for USFieroSend a Private Message to USFieroEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by jimbolaya:


Pre cat O2 sensor.

Jim


If its past the junction on the manifold and in the exhaust tube, I'd check to see if the junction 'donut' is cracked. If it's in the exaust manifold, I'd look to see if the gasket is cracked where it meets the head. It would take spraying some soapy water on the cold exhaust and watching to see if there is any blow-by as it starts/runs. before it gets hot enough to just vaporize the water.
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