I have couple of problemms with my 97 420, both related to evap system.
The 2 codes are P0455(evap. system leak -large) and P0446(evap system vent circuit malf)
I already replaced the vent, but nothing happen'.
Before this problem, i had replaced two O2 sensors and both side cats.
Is anybody out there who encounter this problems with evap system?
The car is running ok, but the check engine light comes back every 50k...together with the anouncement on the dash: check electronics
Please help. I have this problem for about 6 mo now....
Thanks

 

You need to check the evap lines for damage/splits including all connections.
Best way is to blank off one end of each tube in turn and then see whether line holds pressure or better still vacuum.

....Occurs every 50k..... You've had the car for 6 mo.? You do a lot of miles or was this an error?

Stuart