For whatever reason, whenever my son drives our 2001 Vanden Plas, the check engine light illuminates. He's been away at college since December and the first drive upon his return, the light is blazing! There are two codes - P0456 which is a vacuum leak and P1642 CAN controller. I'm no certified technician but can these two codes be related - one causing the other one? I've researched online the possible remedies but need to look at the vehicle when I get time. Last resort is to take it to the shop as I have little patience for diagnosing check engines! Thanks for the direction.

 

Search for the codes to see what the definitions are as they have been reported before. But unless you can DIY the repairs I don't see any other solution except to take it to a shop?

Thanks for the actual codes as that's where you need to start. I would clear the codes and drive the car to see what comes back. Just to make sure we are not looking at "historic codes".
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Start by cleaning the gas cap of debris and pollen, clean the seal, then retighten it (make it click). Then clear the codes and see what gives . . .

 

I cleaned the gas cap and surrounding area yesterday. Will clear the codes later today and hope for the best!

 

Might also try a hard battery reset (touch the negative battery lead to the positive terminal, reconnect negative and start the car).

 

Info for you.

CAN bus wires can get chewed by rodents when a car sits unattended for a period of time?

 

I would visually inspect the related wiring harness and connectors. Check
for damaged components and look for broken, bent, pushed out, or
corroded connector pins for the P1462. For the P0456 there are a
lot of components that can cause that flag. As stated, the gas cap can
have an air gap, but there are a lot of rubber tubes and plastic containers
that can get punctured or worn that can cause vacuum loss in the Jaguar
XJ8 Evap system.