OBD1 and O2 or Cat detection

[pdude]

Will a 1994 Chevy with OBD1 detect issues with O2 or a Cat? I read somewhere it didn't, but my CO detector goes crazy when my truck is in the garage with the CO detector close by as it goes to 240 PPM. Not sure it will pass smog in CA which I have to do soon. I have a DTC code for my ignition only (42) so maybe I will need to fix more that that to get it to pass.

 

[Drunkcanuk]

Will a 1994 Chevy with OBD1 detect issues with O2 or a Cat? I read somewhere it didn't, but my CO detector goes crazy when my truck is in the garage with the CO detector close by as it goes to 240 PPM. Not sure it will pass smog in CA which I have to do soon. I have a DTC code for my ignition only (42) so maybe I will need to fix more that that to get it to pass.

The reason OBD1 won't detect a issue with the cat is because the O2 sensor is upstream of it. It really doesn't even know or care if there is a cat or not.

 

[Schurkey]

High CO is a symptom of a rich mixture.

How old is the O2 sensor--they get lazy with age, and often inaccurate also.

What is the fuel pressure?

Follow the service manual diagnostic procedure for the code.

 

[1997]

start with what you know has to be repaired.

42	Ignition control module (ICM) – electronic spark timing (EST)/ignition control (IC)/bypass circuit malfunction	Wiring open circuit/short circuit to ground, ICM, ECM