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Discussion Starter · #1 ·
I'm having several issues.
first i'm having heater not working on either upstream or down stream, both are new sensors. i have traced that i have 12v at each sensor, so i assume its the ground lines causing me issues, need schmatic to trace that down.

second, i was looking for bad grounds, i found corroded off wires behind the head the 4 ground wires for the coils were a mess, then the ground to the block near the oil filter had 3 of the wires corroded off, i was hoping this would fix it but nope,
are there other problem ground locations???

here is third problem, may all be tied into the same problem, when car is idleing, it runs smooth, then runns crappy then smooth, i looked at the live data and the upstream sensor goes on a slow curve up in voltage, then back down and then back up, thus causing the mixture problem i know it should be a much faster rate of change. any ideas????

driving me crazy and i need to get this fixed before October.


thanks for any insight
Tony.
 

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Discussion Starter · #3 ·
Ok, went thru all grounds, all good and clean. Here is what I have now, checking cat temp 1s1 started at 72 but was upto 800 in 20 seconds, so I assume heater is working? I ran it a while and got the following pending codes poo30 poo36 po102 (fixed by reconnecting lose wire) po172 and po443 now the 443 Ivan understand may be causing my surging and rich problem. But what on earth else do I do about the freeking O2 sensor heaters??? I know they have power, they are both new sensors???
 

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This is just a motherhood comment but.....
What brand and part number did you install for the O2 sensors...
The O2 sensor company should tell you what and how to check them for DOA parts.

While it’s a pain by your self.... ring out the wires from the O2 sensor to the ECU connector or fuse block connector. This way we verify you can get the heater circuits working. We can also measure the resistance of the O2 sensor’s heater. They are easy enough to identify. Their 4 wires are 2black and 2 white. It’s easy enough to find what color are the heater wires and nominal resistance....
I don’t have the schematics in front of me but they are around and one can find them.
If you have a code reader that has a data stream view....what is the wave form do your O2 sensors?..... the up stream should be changing fairly often ~.25-1.0Hz down stream should be quite stable only changing once every few seconds at most.

Check out Is there a common failure point on O2 wiring harness
 

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Help us slow folks by making it a bit easier to follow and easier to read such as
..... got the following pending codes ...
poo30
  • Faulty Heated Oxygen Sensor (H2OS) Bank 1 Sensor 1 circuit
  • Heated Oxygen Sensor (H2OS) Bank 1 Sensor 1 circuit fuse
  • Heated Oxygen Sensor (H2OS) Bank 1 Sensor 1 circuit open shorted to ground
  • Heated Oxygen Sensor (H2OS) Bank 1 Sensor 1 circuit poor electrical connection
  • Faulty Powertrain Control Module (PCM)

poo36
  • Faulty Heated Oxygen Sensor (H2OS) Bank 1 Sensor 2
  • Heated Oxygen Sensor (H2OS) Bank 1 Sensor 2 fuse
  • Heated Oxygen Sensor (H2OS) Bank 1 Sensor 2 harness is open or shorted
  • Heated Oxygen Sensor (H2OS) Bank 1 Sensor 2 circuit poor electrical connection
  • Faulty Powertrain Control Module (PCM)
po102 (fixed by reconnecting lose wire)
po172
  • Faulty Front Heated Oxygen Sensor
  • Faulty Spark Plugs
  • Faulty Mass Air Flow (MAF) sensor
  • Exhaust Gas Leaks
  • Ignition Misfiring
  • Incorrect Fuel Pressure
  • Faulty Fuel Injectors
and
po443 now the 443 Ivan understand may be causing my surging and rich problem.....
  • Faulty Evaporative Emission (EVAP) Purge Solenoid Control
  • Evaporative Emission (EVAP) Purge Solenoid Control harness is open or shorted
  • Evaporative Emission (EVAP) Purge Solenoid Control circuit poor electrical connection

This seems like the mice may have been eating on the wires......check the fuses and trace out the wires.

If you know of another 07 or 08 cobalt, you could test your ECU on their car to rule out the ECU. It’s all just unplug and swapped out in 30 sec, While your there......Check the fuse. Excuse me I don’t have the under hood fuse location handy..l

By removing the connectors a couple of times it may burnish the contacts that may have some corrosion on the contacts.

So is your cobalt living on salted roads or near the ocean?
Most of the codes you posted are saying
Poor electrical connections and could point to the ECM connection
 

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Discussion Starter · #6 ·
H
This is just a motherhood comment but.....
What brand and part number did you install for the O2 sensors...
The O2 sensor company should tell you what and how to check them for DOA parts.

While it’s a pain by your self.... ring out the wires from the O2 sensor to the ECU connector or fuse block connector. This way we verify you can get the heater circuits working. We can also measure the resistance of the O2 sensor’s heater. They are easy enough to identify. Their 4 wires are 2black and 2 white. It’s easy enough to find what color are the heater wires and nominal resistance....
I don’t have the schematics in front of me but they are around and one can find them.
If you have a code reader that has a data stream view....what is the wave form do your O2 sensors?..... the up stream should be changing fairly often ~.25-1.0Hz down stream should be quite stable only changing once every few seconds at most.

Check out Is there a common failure point on O2 wiring harness
Hi, thanks. I have traced 12v to both sensor plugs, it's the ground return line I have no idea on. I think they were ntk sensors.seems off both would be bad out of the box.
My reader does data stream but no eave form. Sensor 1 changes around, not very fast however now that I know the purge valve shows bad it may explain the surging, getting a new one tomorrow. But basically it swings on a curve drops down to maybe .045 then swings up to .090 approx, then back down. Car chuggs too rich then leans out then rich... I will check the heater resistance on both tomorrow. Should be under 10ohms from what I've read.
Thanks
 

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Cool. Good luck.
Just confirm the grounds by the coolant tank,
behind cylinder 4,
at the engine transmission mount,
and there is one between the starter and AC compressor on the engine block. I would take them off and burnish the chassis and terminal. Then reassemble with good grease or good conductive grease! I use permatex copper anti-size for grounds in the engine compartment
 

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Discussion Starter · #8 ·
This is just a motherhood comment but.....
What brand and part number did you install for the O2 sensors...
The O2 sensor company should tell you what and how to check them for DOA parts.

While it’s a pain by your self.... ring out the wires from the O2 sensor to the ECU connector or fuse block connector. This way we verify you can get the heater circuits working. We can also measure the resistance of the O2 sensor’s heater. They are easy enough to identify. Their 4 wires are 2black and 2 white. It’s easy enough to find what color are the heater wires and nominal resistance....
I don’t have the schematics in front of me but they are around and one can find them.
If you have a code reader that has a data stream view....what is the wave form do your O2 sensors?..... the up stream should be changing fairly often ~.25-1.0Hz down stream should be quite stable only changing once every few seconds at most.

Check out Is there a common failure point on O2 wiring harness
Ok, just read that thread, one hit me though not sure it could cause this was exhaust system ground strap broken? I have not looked for this! Where is it located?
Thanks for the help
Help us slow folks by making it a bit easier to follow and easier to read such as
..... got the following pending codes ...
poo30
  • Faulty Heated Oxygen Sensor (H2OS) Bank 1 Sensor 1 circuit
  • Heated Oxygen Sensor (H2OS) Bank 1 Sensor 1 circuit fuse
  • Heated Oxygen Sensor (H2OS) Bank 1 Sensor 1 circuit open shorted to ground
  • Heated Oxygen Sensor (H2OS) Bank 1 Sensor 1 circuit poor electrical connection
  • Faulty Powertrain Control Module (PCM)

poo36
  • Faulty Heated Oxygen Sensor (H2OS) Bank 1 Sensor 2
  • Heated Oxygen Sensor (H2OS) Bank 1 Sensor 2 fuse
  • Heated Oxygen Sensor (H2OS) Bank 1 Sensor 2 harness is open or shorted
  • Heated Oxygen Sensor (H2OS) Bank 1 Sensor 2 circuit poor electrical connection
  • Faulty Powertrain Control Module (PCM)
po102 (fixed by reconnecting lose wire)
po172
  • Faulty Front Heated Oxygen Sensor
  • Faulty Spark Plugs
  • Faulty Mass Air Flow (MAF) sensor
  • Exhaust Gas Leaks
  • Ignition Misfiring
  • Incorrect Fuel Pressure
  • Faulty Fuel Injectors
and
po443 now the 443 Ivan understand may be causing my surging and rich problem.....
  • Faulty Evaporative Emission (EVAP) Purge Solenoid Control
  • Evaporative Emission (EVAP) Purge Solenoid Control harness is open or shorted
  • Evaporative Emission (EVAP) Purge Solenoid Control circuit poor electrical connection

This seems like the mice may have been eating on the wires......check the fuses and trace out the wires.

If you know of another 07 or 08 cobalt, you could test your ECU on their car to rule out the ECU. It’s all just unplug and swapped out in 30 sec, While your there......Check the fuse. Excuse me I don’t have the under hood fuse location handy..l

By removing the connectors a couple of times it may burnish the contacts that may have some corrosion on the contacts.

So is your cobalt living on salted roads or near the ocean?
Most of the codes you posted are saying
Poor electrical connections and could point to the ECM connection
Yes, sorry will try to make it easier.

Yes fuse is good and 12v is at both sensor plugs

No on anyone else I can ECM swap with.

Have not found any chewed wires only corroded wires on both grounds I had mentioned. All soldered and sealed up now.

Yes we have salt, I'm in my, but I've looked at much of the harness no sign of breaks or corrosion.

Yes I have removed and reseated ECM connectors,. Pulled fuse block checked under for any issues all spotless.

Thanks
Cool. Good luck.
Just confirm the grounds by the coolant tank,
behind cylinder 4,
at the engine transmission mount,
and there is one between the starter and AC compressor on the engine block. I would take them off and burnish the chassis and terminal. Then reassemble with good grease or good conductive grease! I use permatex copper anti-size for grounds in the engine compartment
i pulled the coolant tank and fuse box today, got that one, the one on the shock tower, the one near the headlight bucket by the ecm, i redid the one on the engine on the head, it was a mess, and the one on the block by the oil filter

i will look for one by the ac compressor, i'm thinking the one you mention by the engine transmission mount may be the one i'm talking about below the oil filter? i will look again though. thank you very much!
tony
 

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Discussion Starter · #9 ·
Found the one near the ac compressor,. Looks like a pain to get to, but it looks solid. I just looked all around the trans mount even used my endoscope and don't see anything? Either I don't have that ground, it already fell off, or I'm looking in the wrong place? I'm going to test resistance on the sensors now. Thanks
Tony
 

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Tony,
Not familiar with the exhaust ground strap on the Cobalt. I will see what I can find on it.
I “think” you should find that block ground between the starter and AC compressor goes to the double bolt located on the transmission side of the engine to transmission bolt. Should be seen as a major grounding point on the transmission side just to the right of the oil filter.
Here are the images I just took for you

Engine/transmission ground.
Motor vehicle Light Automotive fuel system Automotive design Automotive tire



Ground under coolant overflow tank
Tire Automotive tire Hood Automotive lighting Automotive design


Front chassis ground near the upper radiator hose
Automotive tire Vehicle Motor vehicle Fixture Steering part


Not shown is the ground behind cylinder #4.

Best of luck bashing it back into submission. I hate to throw parts at it but a spair 07 or 08 Cobalt ECU from the salvage yard may be in order. Others would work but would need to be programmed for the L61 2.2L Ecotec. A 07 or 08 Cobalt ECU would at most force you to bond the ECU to your BCM. If necessary, That you can do yourself.....with a fully charged battery.
 

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Discussion Starter · #11 ·
This is just a motherhood comment but.....
What brand and part number did you install for the O2 sensors...
The O2 sensor company should tell you what and how to check them for DOA parts.

While it’s a pain by your self.... ring out the wires from the O2 sensor to the ECU connector or fuse block connector. This way we verify you can get the heater circuits working. We can also measure the resistance of the O2 sensor’s heater. They are easy enough to identify. Their 4 wires are 2black and 2 white. It’s easy enough to find what color are the heater wires and nominal resistance....
I don’t have the schematics in front of me but they are around and one can find them.
If you have a code reader that has a data stream view....what is the wave form do your O2 sensors?..... the up stream should be changing fairly often ~.25-1.0Hz down stream should be quite stable only changing once every few seconds at most.

Check out Is there a common failure point on O2 wiring harness
Ok, just read that thread, one hit me though not sure it could cause this was exhaust system ground strap broken? I have not looked for this! Where is it located?
Thanks for the help
Help us slow folks by making it a bit easier to follow and easier to read such as
..... got the following pending codes ...
poo30
  • Faulty Heated Oxygen Sensor (H2OS) Bank 1 Sensor 1 circuit
  • Heated Oxygen Sensor (H2OS) Bank 1 Sensor 1 circuit fuse
  • Heated Oxygen Sensor (H2OS) Bank 1 Sensor 1 circuit open shorted to ground
  • Heated Oxygen Sensor (H2OS) Bank 1 Sensor 1 circuit poor electrical connection
  • Faulty Powertrain Control Module (PCM)

poo36
  • Faulty Heated Oxygen Sensor (H2OS) Bank 1 Sensor 2
  • Heated Oxygen Sensor (H2OS) Bank 1 Sensor 2 fuse
  • Heated Oxygen Sensor (H2OS) Bank 1 Sensor 2 harness is open or shorted
  • Heated Oxygen Sensor (H2OS) Bank 1 Sensor 2 circuit poor electrical connection
  • Faulty Powertrain Control Module (PCM)
po102 (fixed by reconnecting lose wire)
po172
  • Faulty Front Heated Oxygen Sensor
  • Faulty Spark Plugs
  • Faulty Mass Air Flow (MAF) sensor
  • Exhaust Gas Leaks
  • Ignition Misfiring
  • Incorrect Fuel Pressure
  • Faulty Fuel Injectors
and
po443 now the 443 Ivan understand may be causing my surging and rich problem.....
  • Faulty Evaporative Emission (EVAP) Purge Solenoid Control
  • Evaporative Emission (EVAP) Purge Solenoid Control harness is open or shorted
  • Evaporative Emission (EVAP) Purge Solenoid Control circuit poor electrical connection

This seems like the mice may have been eating on the wires......check the fuses and trace out the wires.

If you know of another 07 or 08 cobalt, you could test your ECU on their car to rule out the ECU. It’s all just unplug and swapped out in 30 sec, While your there......Check the fuse. Excuse me I don’t have the under hood fuse location handy..l

By removing the connectors a couple of times it may burnish the contacts that may have some corrosion on the contacts.

So is your cobalt living on salted roads or near the ocean?
Most of the codes you posted are saying
Poor electrical connections and could point to the ECM connection
Yes, sorry will try to make it easier.

Yes fuse is good and 12v is at both sensor plugs

No on anyone else I can ECM swap with.

Have not found any chewed wires only corroded wires on both grounds I had mentioned. All soldered and sealed up now.

Yes we have salt, I'm in my, but I've looked at much of the harness no sign of breaks or corrosion.

Yes I have removed and reseated ECM connectors,. Pulled fuse block checked under for any issues all spotless.

Thanks
Tony,
Not familiar with the exhaust ground strap on the Cobalt. I will see what I can find on it.
I “think” you should find that block ground between the starter and AC compressor goes to the double bolt located on the transmission side of the engine to transmission bolt. Should be seen as a major grounding point on the transmission side just to the right of the oil filter.
Here are the images I just took for you

Engine/transmission ground.
View attachment 19995


Ground under coolant overflow tank
View attachment 19993

Front chassis ground near the upper radiator hose
View attachment 19994

Not shown is the ground behind cylinder #4.

Best of luck bashing it back into submission. I hate to throw parts at it but a spair 07 or 08 Cobalt ECU from the salvage yard may be in order. Others would work but would need to be programmed for the L61 2.2L Ecotec. A 07 or 08 Cobalt ECU would at most force you to bond the ECU to your BCM. If necessary, That you can do yourself.....with a fully charged battery.
thanks for the pics, will check again.

the o2 sensors mesured 8ohms for the down stream, and i think it was around 11ohms for the upstream...

if all else fails, and i get a salvage yard ecm, how do i 'bond' the bcm to it? never did that before?
thank you for all the help.
 

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Tony,
If you MUST bond the ECU to BCM for the GM security....
There is a published procedure. . Key on wait too long...key off ..stand on your head...wait some time, take 3 steps back....repeat..do it a second time...then try to start
It’s published and takes about 30 min with the ignition on...turn all accessories and lights off to save the battery..... or have a stable DC power source connected to your battery....
Naturally any voltage spikes the BCM’s cpu will invalidate and force a restart....
What I can’t tell you is if it is mandatory.....
Plug it in and try to start your car. If it will no longer turn over and presents a security warning on the information display....you will know..so no surprise.
I just can’t suggest you spend bucks and not have it solve your problem
 

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Discussion Starter · #14 ·
Solonid is changed, no code for that now, but mixture is hunting rich and then lean over and over. Guess I will check the salvage yard for a ECM dunno.
 

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Discussion Starter · #16 ·
UPDATE
after finding a coroded off wire on the air injector control valve, and repairing it after i got a po411c i went and ordered another pair of new o2 sensors. even though i had new ones in it.

results: b1s1 N error
b1s2 still heater error

wth...

back to rock auto, got yet another new b1s2 ntk sensor, NO codes!

what on earth? i just don't get why so picky?

but at this point no codes, i've got over 10 warmup cycles no pending codes
all monitors have run except cat and evap. trying to get them to run so i can get inspected tuesday!

i do have one more issue, this is new

i noticed today after running it up and down the road, the temp was upto 207 and no fans??
fuses are good, pulled the relays, has 12v to both the relay power pin and the actual fan power, but nothing is turning the relay on? i jumpered it and the fan runs fine.
i don't have a schmatic of that, any ideas what triggers the relay and why it is not???

thanks!
tony
 

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Congrats. Looks like your closing in on it. The cat monitor should complete within one or 2 more cold drive cycles...if all is well. The evap monitor may take a bit longer and will not start until all others are complete and then only runnfrom a cold start with more than 3/8 and less the 3/4 tank of gas.

207F with no fan...no problem...
One can quickly check the fan ....
With engine warm..,idle....Park....pop hood ...check is fan running
Yes....ok
No...turn AC on...
is fan working...yes..ok
No. Is AC making cold air....yes..ok
No. Come back and report.

The BCM sends the trigger to the fan relays.
Basd upon the AC pressure and engine temp sensors.
 

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Congrats. Looks like your closing in on it. The cat monitor should complete within one or 2 more cold drive cycles...if all is well. The evap monitor may take a bit longer and will not start until all others are complete and then only runnfrom a cold start with more than 3/8 and less the 3/4 tank of gas.

207F with no fan...no problem...
One can check the fan ....
With engine warm..,idle....Park....pop hood ...check is fan running
Yes....ok
No...turn AC on...is fan working...yes..ok
No. Is AC making cold air....yes..ok
No. Come back and report.
 

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Discussion Starter · #20 ·
Congrats. Looks like your closing in on it. The cat monitor should complete within one or 2 more cold drive cycles...if all is well. The evap monitor may take a bit longer and will not start until all others are complete and then only runnfrom a cold start with more than 3/8 and less the 3/4 tank of gas.

207F with no fan...no problem...
One can quickly check the fan ....
With engine warm..,idle....Park....pop hood ...check is fan running
Yes....ok
No...turn AC on...
is fan working...yes..ok
No. Is AC making cold air....yes..ok
No. Come back and report.

The BCM sends the trigger to the fan relays.
Basd upon the AC pressure and engine temp sensors.
it passed inspection yesterday morning! and so far no lights!

the fan may just be wasn't hot enough to trigger it yet, i read it hits around 210 degrees.
i'll cross that bridge when i come to it i guess, when driving its around 190. i'm good with that!

thank you again for all your help!
still don't understand why the o2 issues but i'm good, for now anyways!
tony.
 
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