Help! Ugggh! P0158, P0174, P1153 CE 1996 LT1

[SGTiger]

CE 1996 Lt1

Getting these codes consistently:

P0158 - Bank 2 Sensor 2 High Voltage
P0174 - Bank 2 System Too Lean
P1153 - Heated Oxygen Sensor Circuit, Insufficient Activity Bank 2 Sensor 1

Any chance the fix is as simple as changing out the Bank 2 Sensor 2?

Thanks in advance for any and all help and suggestions!

 

[Hib Halverson]

CE 1996 Lt1(snip)
Any chance the fix is as simple as changing out the Bank 2 Sensor 2?

Not likely.
You actually have three problems.

The rear sensor on the right side or that sensor's circuitry has a problem.

The system is lean, which is driven by readings from the front sensor on the right bank. That code sets when the system reads so lean that all available rich fuel trim is being used and the mixture is still lean.

The front sensor on the right bank is "lazy".
You can consult the diagnostic information in the '96 service manual and follow its instructions to a solution or you can "throw" parts at the problem and hope.

If you're up for proper diagnosis before repair, you can order Service Manuals from Zip Products. You may also need a Scan Tester

If you're going to try guessing, try replacing the two sensors on the right side but know that might not fix the problems.

 

[SGTiger]

Thanks for the reply!

I have the service manuals and a scan tester. I just couldn't find the diagnostics section for my problem, but after you posted that I looked harder. According to the manual, I should address P0158 before worrying with P0174 and P1153.

It says to unplug the MAF sensor and see if it corrects P0158 which I did. After I reset the codes, I drove for about 30 minutes and got no codes other than the one telling me the MAF is unplugged.

It says if this resolves P0158, to replace the MAF sensor. At this point, I think I should drive it for a day or more to see if the other three codes come back before replacing the MAF sensor. Usually those 3 codes come back within 5 minutes and I drove it for 30 minutes, but who knows?

 

[Hib Halverson]

You always start with the lower codes first.

Good luck.

 

[SGTiger]

You always start with the lower codes first.

Good luck.

I did not know that. For each of the codes, P0174 and P1153 the manual says to address other codes first. P0158 did not say that. I made the assumption that the reason for this is that P0174 and P1153 are types of codes that are often secondary to other causes. However, I don't know what I'm doing and assuming rarely works.

Regarding the problem, my wife drove the C4 to work today and said it ran like crap the whole way. This after I test drove it for 30 minutes last night. I'm anxious to see if the same old codes were thrown or if the "running like crap" was due to the MAF being unplugged.

 

[SGTiger]

Okay fellows, I need advice. After unplugging the MAF last night, no other codes have appeared. Wife said it drove rough on the way to work this morning (about 45 mins one-way). Maybe that was due to having no MAF sensor? Drove fine on the way back home this evening when it was a little warmer.

I checked the codes and still only have the one about the MAF being unplugged. Is this enough evidence that I should replace the MAF (have already spray cleaned with MAF cleaner)? I hate to plunk down that money if I'm wrong.

Should I plug the MAF back up first and see if the old codes listed above return.... or should I go buy a new MAF sensor?

 

[Hib Halverson]

As for the car running crappy with the MAF disconnected, that's normal. Drivability degrades when the engine tries to meter fuel using a derived rather than measured air flow into the engine.

Also, I said earlier you should "You always start with the lower codes first."

Ooops. My bad. :duh
Don't take that advice. Follow the FSM. That's an old OBD (81-95) rule of thumb which doesn't apply to 96-up w. OBD2 emissions controls.

Things get complicated when you really start reading the book. For instance, for P0174 to set, 1153 can't be set. That implies that 0174 set before 1153.

I'm sure you read in the diagnostics for 0174 and 1153 that if other codes are set in addition to them, you should do the other code first so, you need to be working on 0158. If that's not where you started, I'd reconnect the MAF, clear codes then go for a long road test. As soon as the MIL comes on, stop and read codes with your tester to see which of the three set first. Then continue the road test w/o clearing codes to see what others may set.

Once your done with the road test look at the freeze frame data and failure records for additional info.

Consult the diagnostic instructions for codes which do not say: "If other codes are set, do them first."

 

[SGTiger]

Just wanted to follow up now that it is fixed in case it helps anyone else down the road.

The bank 2 sensor 1 was the root cause of all these codes. After this sensor was changed, no more codes and no more rough idle.

 

[Hib Halverson]

Case closed, eh.
That one was easier to solve than I thought it would be.