check engine light won't reset - no bad codes

redptc
Posts: 6
Joined: Fri Aug 29, 2014 4:04 pm

check engine light won't reset - no bad codes

Postby redptc » Fri Aug 29, 2014 4:10 pm

I have a 1987 FX-16 GTS and the check engine light is always on. When I check the codes it says there are no errors. How can I get the light to reset? I have tried disconnecting the battery for a day to let the power drain but that had no effect. Thanks!

BTW, I bought the car new. It now has over 176K miles on it and I still smile every time I get behind the wheel. What a great car! :D

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ae82hybrid
Club4AG Regular
Posts: 26
Joined: Thu Jan 10, 2013 9:58 pm

Re: check engine light won't reset - no bad codes

Postby ae82hybrid » Wed Sep 03, 2014 4:20 pm

I've had an issue like this before where my CEL stayed on constantly and there was no DTC present. It turned out to be a electrical problem in the interior harness leading to the ECU, you might not be having the same electrical problem or an electrical problem at all but for my issue it turned out that a few wire pins (I can't recall which wires) were loose at the pigtail connector and I only found that out by wiggling the harness behind the connector and the CEL kept going on and off. Check your "grounds" and it might be worth a shot trying to wiggle a few wires. Good luck.

redptc
Posts: 6
Joined: Fri Aug 29, 2014 4:04 pm

Re: check engine light won't reset - no bad codes

Postby redptc » Wed Nov 05, 2014 2:44 pm

I have a new clue. I took the car on a road trip and whenever I got above 4000 RPM in 5th gear (and sometimes in lower gears) the CEL would go out. It ALWAYS came back on as soon as the engine dropped below 4000 RPM. That gave me a good indicator whenever I dropped below 80MPH. ;-)

taroroot
Club4AG Enthusiast
Posts: 103
Joined: Mon Jan 14, 2013 10:04 pm

Re: check engine light won't reset - no bad codes

Postby taroroot » Sat Nov 15, 2014 5:26 am

Given that info, I'd suspect a bad AFM or throttle position sensor. Kinda weird it wont through a code though. Hm, but its inconsistent. I'd search for bad wiring too.

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