what could be causing this? I can pull a code from the ECU but the CEL doesn't turn on while the car is running. It does turn on to count the pulses and when the ignition is ON. If I clear the code it just comes back but without the CEL. I make sure the code is cleared by counting the pulses again after clearing. It give me 0505, then after running the car for a while it gives me a real error code, which I'm working on too.

 

What is the code? A knock sensor fault, for example, (3 short, 4 long) is a "ghost code" that will not light up the bulb.

 

It's 0607 cylinder 2 misfire.

 

I finally got the CEL to come on by disconnecting the bad injector that was causing the cyl 2 misfire and driving the car with it unplugged. Very strange, but I guess a bad injector can cause the CEL to not light up.