Hey guys, have a question you can hopefully answer.

I have a 99 Si with a ODB2b to OBD1 conversion harness and a chipped p28.

I'm getting an instant CEL, it comes on when I turn the key to ignition without even starting the motor.

I've tried jumping the ECU to pull codes but it doesn't do it, the CEL just stays constant.

When started the car idles and runs fine, no limp mode.

My plugs are new and I'm in the process of changing my O2 sensor, had a few limp mode drives before I got the p28, and it has to be bad by now. But I don't if that will take care of it.

What else could it be, maybe another sensor I need to unplug or rewire???

Appreciate any help thanks.

 

It still comes up even when I reset the ECU by pulling a fuse......

 

My guess it's either the conversion harness or the ECU. If possible try another conversion harness (a friend or someone local) and ECU.

 

Yeah I'll try that, I have a 95 prelude ECU, it's not VTEC, but it may show me if the CEL comes on with it or not. Thanks.

 

My reply is from experience. I have had cars throw a solid many times. 99% of the time it ends up being the wiring or ECU.

 

Thanks man, it was the ECU, I just got another one from phearable and it works perfect.

 

It's no problem. I had no doubt in my mind that would be it. You purchased from a good guy as well.