hey guys, a couple times a day when i am driving at the same rpm for a while my truck will give me the c.e.l. it will the proceed to shut off if i change the rpm either up or down. i did my research and found this to be most likely caused by a bad or going out o2 sensor, but my truck doesnt ever seem to store a code for this. no matter how long the c.e.l is on. i have a toggle switch wired in so checking the codes is as simple as flipping a switch. and when i do the c.e.l doesnt flash any codes. i know its probably not a big issue but it buggs the crap out of me some times. anybody kno what could cause this?

 

Anyone?

 

Like you mentioned that changing the rpms will make the light go out. I have had a similar issue that you are experiencing and it was from a small vacuum leak. I would check/replace hoses as needed. Most likely your O2 sensor is in bad shape as well.

 

Only CEL I had that would turn on and off was a code 25, Lean Air/Fuel Ratio. Don't assume that's your issue though. Mind ended up needing a valve adjustment since the fuel was exiting the chambers because of a stuck intake valve. But a code 25 could be a dozen different things, one of which is a vacuum leak.

 

whats weird about it is that its not storing a code in the ecu so its hard to find a starting point on where to find the problem. ill check for a vacuum leak and try a new o2 sensor first off.