How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Richard Your Own Question
Richard, Jaguar Technician
Category: Jaguar
Satisfied Customers: 15307
Experience:  12 years at a Ford/Lincoln Mercury and Jaguar dealer as technician and shop foreman.
Type Your Jaguar Question Here...
Richard is online now
A new question is answered every 9 seconds

I have a 2007 4.2 Jaguar XK coupe. On four occasions in the

This answer was rated:

I have a 2007 4.2 Jaguar XK coupe. On four occasions in the last 8 months the vehicle has accelerated violently without the throttle being operated by the driver. Fortunately,by standing on the brakes and having the presence of mind to select neutral the vehicle stopped without killing someone. Another occasion, just sitting in the car on my drive,in reverse gear, the vehicle did exactly the same. This time I could watch the tachometer to see it ran up to 2500 rpm and lasted for about 10 seconds, then died back to normal speed and I reversed off the drive, very carefully carrying out my journey. Then 2 weeks ago as I drove away from a friends house it suddenly shot away engine screaming. I was 200 yards from a busy T junction! Again, standing on the brakes I sought to select neutral, unfortunately hitting reverse and locking up the gearbox. The car I bought for fun is a driver's nightmare as it could just leap forward as I am moving slowly and kill someone - it really is as fast as that. The car has been in Guy Salmon Jaguar since last Tuesday but they can't find any defect code showing the fault. I have been told the car is fitted with a 'Black Box' (like an aircraft) and this records everything the car does, including spontaneous throttle operation. Guy Salmon still have my car and can't find the fault. On the basis it occurs about every 3000 miles and only at low rpm
will I ever see my pride and joy back and a pleasure to drive, not the white knuckle ride it is at the moment. If very reputable Jaguar dealers such as Colliers and Guy Salmon can't sort it out, then who can? Please help, but be kind on price as I don't know if Jaguar will allow me compensation for their work on this rogue car that I love but hate to drive!!

Hello, I'm Chris. Thanks for visiting Just Answer.


I am sorry you have had to wait so long for the first contact. Sometimes this happens when the question you ask is not detailed enough or its just hard to address online. Many have viewed your post, but have passed. I am checking to see if you still need help.

I am not going to lie, this concern is not my strongest point, but I will do my best to help you. I have access to many repair sites, so at the least I can provide something to address at least part of your concern if it is not something I can address from memory and experience.

I mainly work in the last half of the day, so that is when I do all of my responding. If there is anything else you can add to your concern to help me out more so I can help you out in turn please do so in your next reply.

Once you get an answer, you will be prompted to rate me. You are rating my help, not the website, or answer. If you feel the need to rate negative, please save the rating so I can try again or find someone whom may be able to help better.

Thanks for using our site, we will do all we can to earn your business, again sorry we did not get to you sooner.




Customer: replied 3 years ago.

The information I have provided is,I believe concise and a clear definition of the problem.


I have re-checked my comments and really cannot add anything to describe the problem.


If you ask me what else you need to know, please be more precise.


12.30am and off to bed now but I'll check your response tomorrow am.




Chris XXXX

I am sorry I just noticed your question is on a UK model, I need to opt out and move your post.


Customer: replied 3 years ago.

Not good. When can I expect to hear from the 'Expert' you have transferred me to

Customer: replied 3 years ago.

Dear XXXXX, I know I sent a reply to you but cannot find it in my sent box. So just to be clear, I am not satisfied with this service and urgently need to know when my new expert you have moved me to will make contact.



Hello and welcome to

New expert here. Ok these vehicles do not really have issues with unintended acceleration but like any other vehicle it can be possible. The throttle is fully electronic and if the ECM sees the throttle position open and no signal from the pedal sensor then it would go into limp mode. Since this did not happen your most likely problem is with the pedal assembly which has the sensor in it. It could also be the throttle as well as that is also serviced as an assembly but it is more likely we have a problem with the pedal/pedal sensor.

As far as the black box there is a flight recorder that shows and records data when certain instances occur like an engine stall, no start or vehicle impact. This data can be read by the dealer but it should be escalated and sent directly to Jag as they can read all the info stored.
Richard, Jaguar Technician
Category: Jaguar
Satisfied Customers: 15307
Experience: 12 years at a Ford/Lincoln Mercury and Jaguar dealer as technician and shop foreman.
Richard and other Jaguar Specialists are ready to help you
Customer: replied 3 years ago.

excellent service


chris XXXX

You are very welcome. Keep me posted.
Customer: replied 3 years ago.

Great service to resolve a difficult problem




Chris XXXX


Related Jaguar Questions