CEL light on but no code

[Animatorfor3D]

I own a 95 q45 with 175k. I purchased the car about a year ago. I did an engine oil, transmission and dif flush soon after. The car ran almost perfect after that. Then i was hit from hit from behind by a another car that was hit from behind. I took my car to M2 Colision where they realigned the frame, only 4 inches or so to the right. When i got my car back it was smoking So i took it to a real mechanic and they replaced the valve cover seals and that fixed the problem. Thats when the check engine light started coming on. I couldnt get signal from the ECU at first but when i finally did, i got a knock sensor signal. So i paid to have them tear into the engine again and replace the sensors. Then the CEL came on again. So i took it back again. This time no Code. But the light still kept coming on. So i took it back again And again and again and again. Every time they cant get a code and neither can i. The CEL comes on about 15 mins after the engine warms up. But doesnt come back on right away if i turn it off and on again. What can you do if there is no code, but the light keeps coming on?

[Q45tech]

Most of the things that set codes on a pre OBD2 car are total failures to pass the start up check........the sensor is open or shorted.

The [bad] O2 sensors can cause the situation you describe.

Using the blinking ecu lights is a rough and dirty test. Not very helpful.A Consult is what we use to SEE the REAL PARAMETERS.

[Q451990]

I'd bite the bullet and have a dealership run a Consult diagnostic for you. Let us know what they say...

Heath

[Animatorfor3D]

Is a Consult a little handheld reader device? like maybe a palm or something like that?

[maxnix]

It's Nissan specific with daughter cards. Some independents, but mostly dealer's only.

If you have the chance, be sure to have an experienced Senior Infiniti Technician read and interpret the Consult. I wonder if there is more damamge, like to your exhaust system (at a minimum).