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Richard, UK Car Mechanic
Category: UK Car
Satisfied Customers: 15311
Experience:  12 years as a technician at a Ford and Jaguar dealer Ford and Jaguar factory certified
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I have a 53 plate Jaguar S type. Last week, I had a

Customer Question

I have a 53 plate Jaguar S type. Last week, I had a "Performance Restricted" sign, with Codes P0171, P0174, P1260, P1582 & P1632" (as diagnosed by the AA Patrolman. Took it to the local dealer who was unable to replicate the faults. Now it is in "limp mode". Any ideas please?
JA: How many miles are on the car? Do you happen to have the wiring diagram?
Customer: 115,000 miles. I'm afraid I do not have a wiring diagram. would be nice tho if I could get a workshop manual. As a retired aircraft engineer, I do know how to use manuals!
JA: Are you hoping to fix this yourself?
Customer: Not necessarily as I don't have the diagnostic equipment and my age prohibits me from getting under the car now!
JA: Is there anything else important you think the Jaguar Mechanic should know about your Jaguar?
Customer: Regularily serviced, maybe 10,000 miles per year, not raced, just driven like a normal saloon car, and it's lovely when it's going!
JA: OK. Got it. I'm sending you to a secure page on JustAnswer so you can place the $5 fully-refundable deposit now. While you're filling out that form, I'll tell the Jaguar Mechanic about your situation and then connect you two.
Submitted: 4 months ago.
Category: UK Car
Expert:  Richard replied 4 months ago.

The codes P0171 and P0174 are lean codes which can cause the restricted performance. We need to make sure these fault codes are the ones that have returned. On the V6 engine I see some issues with vacuum leaks from the intake seals, IMT seals as well as vacuum hoses and connections. We also need to check the air intake tube. Other possibilities are a faulty mass air flow sensor or even a clogged fuel filter or weak pump. Start the engine cold and listen for any air or hissing noise form the engine. We also need to scan it again to confirm the faults. Let me know.