Terry Adams

Drove 900 miles with it on. Tech says there's a count down cycle to turn it off. I had not reached the zero yet. He turned it off with PIWIS.
CEL due to gas cap not all the way on till click.

nevil

Good to know. In the 900 miles you drove it, you must have had to gas up at least a couple of times. So even if you tightened the cap after the CEL popped up, it didn't correct itself?

Terry Adams

Right, once the CEL came on, I tightened the cap. Porsche Tech says it starts a timer and doesn't go out till zero, whatever that is.

drcollie

This will also occur if you don't fit the oil fill plug correctly when adding a quart of oil, etc.

boyce89976

When I had my X5M it was a combination of factors... miles, speed, number of starts... that resets a CEL. You may have met some, but not all of the requirements?

Terry Adams

Dealer tech was very busy. All the service adviser had time to explain second hand was, it had not reached zero yet, and they reset it with PIWIS.
From now on, I will twist the cap until click.
My attention span drops after 6+ hours of driving.

DHL

In the OBD II system once a CEL is triggered, a flag is set in the in the main computer. Reseting the fault with a reader "sets" one or more additional flags called "monitors". How many and the specific function of these monitors depends on the original fault. The purpose of the monitors is to monitor (duh) the operation to be sure the original fault does not return. The timing and conditions to RESET these monitors vary by the type of monitor. Some have a driving cycle (ie so many miles above a certain target speed, etc) that must be completed, others have a specific number of start/stop cycles. The monitors will not be completely cleared until all the reset conditions are met for all the monitors. This can take some time depending on the monitor and how often you drive the car. In CA, you cannot complete a smog inspection if any monitor is still active.

VAGfan

It is the number of engine restarts that eventually resets the DTC code associated with the with a loose gas cap. That DTC code is a result of the air leak in the fuel tank vapor recovery system, which is tested once everytime the car is started. If it passes after N (something like 3 to 10 restarts) tests, the code is reset, and the dash warning is extinguished. The "Engine Control Fault" warning is generic, it can be set by about 80 different faults detected by the Engine ECU.