Hello, I was searching the internet on anything related to the fuel composition sensor for gm. I have a 2002 GMC sonoma with ~150k miles on it, and its giving me the code P0176, which means bad fuel comp sensor. Anywho I am aware that I can get a replicator that will bypass the sensor and just tell the comp that its running gas, which is fine because thats all of what is ever going to be ran in it anyways.

My question is this, i'm trying to test to see if its the sensor thats bad or the wiring harness. I checked out a quick diagram of the plug leading into the sensor that stated I should have 5 V at pin A, 12V at pin B and pin C is common. Well I tested it out. Using a part of the frame that had been rubbed to bare metal from the tires as my ground, I got 4 V at pin A, and a lil over 11 V at pin B. Is this still within tolerance? Or does this mean I have too much resistance in the harness?

 

you got some bad information somewhere...maybe your scan tool. p0176 isn't even a valid code for a 02 Sonoma.
a 2002 does not have a fuel composition sensor. They are only used on flex fuel vehicles.

 

It is a flex fuel vehicle. 4 cylinder.
Hopefully the below link works
Kelley Blue Book

 

nope, I checked in the gm service manual. It may be a 4cyl but its not flex fuel and that dtc cannot be set by a 02 Sonoma...only by error...maybe your scan tool is out dated or your putting in the wrong year information.


Whats the last 8 of your vin?

 

28108010

 

The fuel composition sensor is located under the right front fender well, its a sensor bolted to the frame with a 3 pin connector in one end and a fuel line running in and out of it. I know exactly where it is and I've seen the bugger.

 

Kinda had to to get the voltages off of it. I just need to know if those readings are within tolerance, which would make the sensor bad and I can buy a replicator to bypass it, or if its not within range if I need to redo the wiring and the sensor may actually still be good.

 

the vin search does show it is as a flex fuel vehicle.
I searched but cannot find diagnostic information. Maybe the California vehicles have a different section. I will continue looking for information for you.

 

I appreciate it man, I've been searching online but I just seem to come up with different codes, or people talking about replacing the sensor or adding in the replicator, not any actual diagnostic troubleshooting with it.

 

came up with nothing. Don't know why diagnostic information isn't there for that dtc. I've read the fuel system description and operation for 02 up to 04 and no mention of flex fuel or fuel composition is there. Maybe someone can check aftermarket information systems.