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Richard, Jaguar Technician
Category: Jaguar
Satisfied Customers: 15512
Experience:  12 years at a Ford/Lincoln Mercury and Jaguar dealer as technician and shop foreman.
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I'm getting a P1397 and a P1643 message on my 1998 XJ8. I've

Customer Question

I'm getting a P1397 and a P1643 message on my 1998 XJ8. I've just changed the coils and plugs as it had a couple of misfires. The car won't start. I'm charging the battery as it is now flat. Any ideas please?
Submitted: 1 year ago.
Category: Jaguar
Expert:  Richard replied 1 year ago.

Right now the engine is cranking but not starting and is the cause of the battery running down?

Customer: replied 1 year ago.
It's cranking but not starting - correct.
Customer: replied 1 year ago.
There are no error codes for misfire. Just P1000, P1397 and P1643
Expert:  Richard replied 1 year ago.

OK P1397 is for the variable timing and P1643 is a network fault. Neither one should cause the engine to crank but not start. Since you also have a misfire I wonder if the timing has jumped. Sometimes the secondary tensioners fail causing the secondary chain to jump and even break. The only way to check this would be to remove the valve covers to inspect. Of course it can be another fault like a weak fuel pump or clogged filter. We would need to check fuel pressure at the injector rail with a gauge to verify all with the fuel system is ok. Let me know.

Customer: replied 1 year ago.
There's a P1637 code now.A new fuel pump was installed last week before I took delivery...
Customer: replied 1 year ago.
i am also getting messages transmission fail and stability control fail
Expert:  Richard replied 1 year ago.

Ok P1637 is also a CAN network code. See if the engine will start in neutral. Also try spraying some carb cleaner into the air intake to see if the engine will start and run on the spray.