CEL on after 20 min

[jojomanigbas]

95 explorer XLT 4.0L EFI 4WD...

When I turn on the engine everything is fine no CEL.
After 20-30 minutes of driving the check engine light would come on.
The same is true on every startup.
(Start the car up no CEL... drive 20-30 min CEL).

I had dropped the car off at the dealers to pull the codes.
The problem is, when they restart the car the CEL light does not go on - no codes to pull.

I guess they do not want to waste time driving for 20-30 min till the CEL goes on.

Anyway, has anyone encountered this issue and how did you solve it?

Any advice is greatly appreciated.

Thanks,
Jojo

 

[corkey]

unfortunately you need to know the code, could be an o2 code,,or something like inlet air temp,,