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Richard, Jaguar Technician
Category: Jaguar
Satisfied Customers: 15524
Experience:  12 years at a Ford/Lincoln Mercury and Jaguar dealer as technician and shop foreman.
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Jaguar XJS: Im looking at buying a XJ12. Its not running,

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I'm looking at buying a XJ12. It's not running, been told it's a control module issue. What are the most likely causes?

Hello and welcome to


when you say not running is the engine not even cranking or does it crank but not start? Did they say it was the ECU?

Customer: replied 4 years ago.

I believe it to be turning over but not firing. He says Control Module, I'm guessing he means the ECU. I've heard in the past about an issue with these cars not coming up on full power. The problem was a simple fix with aluminum foil. Are you aware of such a repair and could this be the problem?

Well it will be hard to say what the problem may be but I do see some issues with the ECU causing this if in fact we do not have fuel. The first step would be to check for injector pulse, or to see if they are clicking, check for ignition output from the distributor and also check fuel pressure from the pump. It also could be a problem with the water/coolant temp sensor which can cause starting problems.


As far as the vehicle losing power this is usually due to a loss of one bank. It could be the coil or the coil wiring which yes I guess could be fixed with foil or new wiring.


I can tell you that these vehicles are not easy or cheap to repair. Unless you are picking this vehicle up for next to nothing and have a little set aside for repairs it may not be a wise purchase.


Let me know.

Customer: replied 4 years ago.

Thank you for your response, I understand the magnitude of owning a vehicle such as this. I thought it might be feasiable, as I do have some mechanical inclination, having worked as a machinist for several years. I'm weak were it comes to tuning and electrical & fuel systems. The car is for sale at $1900.00
Canadian with 155,000kms on it. Is this a good buy?

It really will be hard for me to say since I cannot see it in person. The price is not bad but if you plan to use it as a daily driver I would pass.
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