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2003 GMC Sonoma P1072 / P1075 codes

My father-in-law’s 2003 Sonoma truck has the check engine light on and I found it was driven by the P1072 / P1075 codes, indicating that both bank 1 and 2 were too rich.
We have tried numerous repairs to fix the issue, including the following:
• Replaced all oxygen sensors
• Replaced a vacuum hose
• Replaced the spark plugs
• Replaced the fuel filter
• Replaced the spider injector assembly
• Cleaned the mass air flow sensor
Despite the above actions, the truck still has the same error codes. He took it to the local Chevy dealer and they could not find what was wrong. His state [New York] has a yearly inspection and the truck will not pass this with an error code, leaving him without a means of transportation – please help!

My brother went through this same scenario and a new air filter finally fixed the problem. The CEL system is not a good way to diagnose a vehicle problem…an experienced and qualified mechanic is your best bet.


Good for you for replacing the spark plugs, fuel filter, and cleaning the MAF sensor. That was good preventive maintenan
Replacing the oxygen sensors was shooting the messenger

I’m assuming you replaced the vacuum hose because it was rotten or split wide open

Now you have to determine if in fact you do have a rich condition, such as high fuel pressure

Has anybody hooked up a vacuum gauge with the engine idling?

Forget the Chevy dealer . . . no offense to them, but they probably can’t think outside of the box. If there’s no factory technical service bulletins, they probably don’t even know where to start. Bring it it to an established and reputable independent shop. They probably better know how to diagnose and repair vehicles

The only thing that you haven’t replaced for the DTC’s P1072 & P1075 that can cause these codes is the MAP sensor.

Here’s the sensor for you vehicle.

Click on: What Does A MAP Sensor Do?


I disagree that the MAP sensor is the only “remaining” thing that could cause P0172 and P0175


They’re DTC’s P1072 & P1075.

Manufacturer Specific codes.


AFAIK P0172 and P0175 are generic versions of P1072 and p1075

And I still disagree that the MAP sensor is the only “remaining” thing that could cause these codes

Somebody needs to diagnose this truck, versus throwing more parts at it

Add up all the parts and labor so far, and it’s pretty expensive.

Some of it was good maintenance, but the fuel spider . . . which isn’t cheap, when considering labor . . . did NOT solve the problem

Time for proper diagnosis and repair, time to put the shotgun away

BTW . . . I agree that the MAP sensor may be a problem, but it’s still time for proper diagnosis

When the first guess is wrong, you just keep guessing, and the bill keeps getting fatter . . . ?

That is not the proper way :frowning:

The OP has either cleaned/replaced all the things that can cause these codes.

So they should at least test the MAP sensor to see if it’s the cause of the rich conditions in banks 1 & 2.



“The OP has either cleaned/replaced all the things that can cause these codes.”

I disagree with you on this

And unless I hear otherwise, I am quite confident that proper diagnosis was NOT performed

After all, there have been several shotgun blasts, and the original problem remains

Proof positive, as far as I’m concerned

I’m done with this particular discussion . . . take the ball and run with it :star: