Check engine and traction control light on

Got in my truck to head home from work and the lights came on with a P0456 code. Anyone had this problem before? I cleared the code and for the 2 mile drive home it stayed off.

 

Did you check the fuel cap?

 

You Check your fuel cap?

 

X3
Done this one before

 

had it as well....It was the fuel cap...I had bought an aftermarket locking cap....The Chinese made cap did not make a good seal...pitched it and replaced with original cap, re-set the codes and all is well.

 

And if im not mistaken...isnt the evaporative system checked at key off?

 

Correct the small and very small leak tests run around 3-6 hrs after the engine is turned off, there's also some other parameters that have to be met before the test will run.
Very small leaks (0.02 in) can be a real pain to track down even with a smoke tester.

 

I did check the cap, nothing seemed wrong as it is the factory cap. After setting over night and the short drive to work this morning it still hasn't came back on.

 

What about a leaking purge valve?

 

Definitely possible, majority of the ones I replace are either stuck closed (typically setting a gross leak code) or leaking bad enough to set incorrect purge flow or purge during non purge codes but I mainly do Ford, GM, and Dodge EVAP systems.
I've had small and very small leaks kick my butt before, they can be very difficult to locate unless a valve is obviously leaking.

 

Thanks for all input everyone. So far it hasn't come back on.