P0690 code and erratic fuel gauge operation

[Batmanntexas]

I started my car yesterday morning and was greeted with a CEL. So, I got out my trusty scan-tool, and read the codes. I had three codes, all P0690 (pending, confirmed, and permanent). I also noticed that the gas gauge was reading incorrectly. Anyways, I cleared the codes and drove the car to work. Car drove fine, no return of the CEL, but the gas gauge continued to read erratically (going from 1/4 to full and various points in between).

So far, I have done the following:
1. replaced the battery with a new one - no change, CEL still pops a P0690
2. Swapped the PWRTRN relay with the RR Defog relay - no change, CEL still pops a P0690

So, is the next step a new PCM? I'll pull the connectors on the current PCM and check those, but this problem came up out of the blue, as I haven't worked on the car in over 2 years, which is making me think the PCM is getting flaky on me.

Thanks,
Scott

[acerider]

I had this problem with one of my cars (not the camaro) and it turned out to be a faulty sending unit on the fuel tank. It registered a check engine light that came, went away and came back repeatedly. The fuel tank indicator worked off and on. Its worth checking.

MJ

[Batmanntexas]

Thanks for the info, I'll check out the fuel sending unit. That might solve the fuel gauge problem, but I don't think it will help out with the other problem, the P0690 that keeps popping.

[dru21281]

Try some Techron Chevron fuel system cleaner before replacing the fuel level sensor. Have had good luck fixing fuel level sensor problems in the past(it will clean the contacts on the sensor, may take 2 treatments/bottles).

Sent from my Pixel 2 XL using Tapatalk