I have a 99 durango 5.9. The check engine light comes on. I have the codes checked and it shows pass, no codes. I clear the light and drive for a while. I have replaced the gas cap, no help. The light comes and go's. Any ideas??

 

This might sound silly, but when you fill up at the gas station do you keep the engine running?

 

Could be a vacum problem. My check engine light will come on when I have the car in 4lo, and I am using the gears to keep the car from blasting down the 4x4 trail. I've been told this is directly related to the vacum in the engine. it usually takes my light a day or two to turn off but then everything is fine.

 

Thanks for the input. I replaced the PCV valve and vacume line. Light has not come back on.

 

Heard that removing gas cap while engine running triggers Check Engine Light.

I just fixed a check engine light condition (error P7020) related to the output speed sensor on the driver side of the trans ($29 at Autozone) as opposed to the "Speed Sensor" I replaced on the rear end differential last year which causes the ABS and Brake Light to stay on.

I have learned that once a problem is repaired, a disconnected battery terminal for 10 minutes clears the associated codes.

Now all I have to worry about is possiblity that the ball joints and the engine sludge issue will return.