Over the past two or three years our '02 300M has turned on the Check Engine Light a few times, and the "key dance" has indicated sometimes P0440 and sometimes P0441. At first the problem did not return for several months after pulling the fuses or disconnecting the battery, but now the CEL comes on again almost immediately.
I understand that both these codes indicate one or more problems with the emissions control system. How much work is involved in tracking down the problem, assuming the worst possible case, and how much might it cost to fix?
I did already replace the gas cap, but that has not solved the problem.
Perce