Check Engine Light - Won’t clear, no codes (1 Viewer)

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My check engine light came on yesterday. I was expecting a code 21 for the O2 sensor since I was tightening a bolt on my sliders and bumped it a bit.

It won’t clear or it comes back on immediately upon starting the truck. I’ve had the battery disconnected and the EFI fuse pulled.

However, when I go to read it the CEL just blinks consistently which indicates the system is working and there are no codes. What gives?

The truck runs the same— maybe a bit rougher at idle but I might be imagining that. There is some white goo on the diagnostic ports. I’m hoping it’s just dielectric grease. This is the first time I’ve had to read a code since buying the truck in July 2017.

 
So it only takes a few minutes to pull the gauge panel off and remove the CEL bulb... :lol:

Maybe try giving it an actual code to read. Un-plug the O2 sensors and see what it does.
 
So it only takes a few minutes to pull the gauge panel off and remove the CEL bulb... :lol:

Maybe try giving it an actual code to read. Un-plug the O2 sensors and see what it does.

Great idea!💡 I might order one to have on the shelf if I don’t need it.

It does actually seem rougher at idle. Would an O2 sensor cause that? I’d think so.

Also a bit down on power after coming off the throttle and getting back on. That seems more serious
 
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Great idea!💡 I might order one to have on the shelf if I don’t need it.

It does actually seem a bit tougher at idle. Would an O2 sensor cause that? I’d think so.

Just curious, did you have the transmission in neutral when you were retrieving the codes?
 
No....missed that part of the fsm :doh:
 
That might be preventing you from getting an actual code reading.
 
If it’s blinking fast, the diagnostic terminals are closed. Look for a shorted wire to cel from ecu. Try a known good ecu. That’s all I got. Good luck
 
CEL is working properly now. whaddaya know putting it in neutral like you’re supposed did the trick #surprise

Code 21 as expected. #1 o2 sensor
 
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