My SES light came on in my 2000 Discovery II SD afew months ago.

The code was PO455 (Evaporative Emission Control System Leak Detected (no purge flow or large leak).

I removed the gas cap, cleared the code and the light never came back on until yesterday.

I had stopped to run a quick errand and ended up leaving the truck idling for about 15 min and the SES was on when I got back to the truck.

I connected the OBDII and it was the PO455 code again.

I cleared the code (didn't touch the gas cap this time) and the code has stayed off after about 50 miles of driving.

Any thoughts as to why this would come on when the truck is left idling but stay off indefinately once cleared?

Thanks,

Art

 

The 455 is "A Gross " and you are are going to need to go thru the whole system to find it, doubt it will be a failed gas cap.

 

Hi Mike,

Thanks for the reply. The light stayed off for a few months after I removed the cap and cleared the code. It came on this time when the truck was left idling for 15 min or so.

I cleared the code and drove the truck about 50 miles and the light has not come back on.

The truck seems to run fine and I average about 15 MPG with mixed driving.

Should I wait to see if the light re appears or is there a specific list of items I need to check?

Thanks,

Art

 

Go with the old saying, " Let sleeping dogs lie".

 

Leaving the truck running has nothing to do with the code coming on.
A gas cap is cheap, replace it with a non vented cap and go from there.