Help! I'm writing on behalf of my mom, who drives a 2003 XJ8 that recently failed inspection with the codes P0447 and P0455. The secondary emissions test shows that everything passed except indicator light -- fail. My question (as a non-car person) is how do we figure out whether it is a problem with the Evaporative Emissions Control System or actually a problem with the OBD? The mechanic says we need a new ECM -- but how do we know it's an ECM problem and not a problem with the actual emissions system? (And is the ECM what controls the OBD?) As you can tell I need a lot of help. Thanks much everyone.

The mechanic doesn't know what he's doing- ECM is not the problem. Just do a google search for:
XJ8 PO447 PO455
to get some ideas how to proceed, and don't take it to a dealer.

Info from Jaguar.
It could be a FAILED CCV (Canister Close Valve) or the circuit to the valve?

I would agree with the canister valve... Check and replace if defective.

Search for a good Jaguar independent and get it fixed -- the tester recommending a new ECU is not the guy!!

Print out Bob's attachment and take it with you along with the rejection notice.

A Jag dealer could do it, but lately, some of these don't want to work on older cars; preferring new ones for the warranty funding.

Do a delete and move to a non communist location. I'd be damned if I let anyone decide the fate of a perfectly fine running vehicle based on a stupid emissions test.
That's insane!

Thanks!!

Change mechanic.

thanks so much!