throttle body issue on an a 2002/2003 XJR
 

Hi,
How often do they go bad and how to detect if one will go bad soon when test driving a car?
I heard they cost over 2800 dollars to replace..

Thank you

There are a couple of throttle body codes that can be read with a generic reader. The throttle body can usually be rebuilt by companies like ASI for a few hundred dollars. Use the search to find a long list of threads discussing the issue.

But the codes are not "about to fail"- They are "have failed"!
Neither of my post 200,000 mile XJRs failed the TB, though.

I remember looking into this a while back and finding one place doing Jaguar TPS work listing the XJR -- the others only list the non SC cars.

The SC cars have a different Tbody.

I had the fault pop up 6 or 7 times over a couple of months a few years back. My Jaguar had about 50k on it at the time -- it was used infrequently. Looking into the design of the TPS I discovered that it uses a monitored double circuit -- dirt on either leg will cause a fault and restricted performance to pop up.

I don't know if the sealed sensor eventually allows moisture or other matter to enter or if the contacts become compromised -- but something is causing a minor electrical disturbance on the contacts as the sensor turns with the throttle.

With the car off I pushed the gas pedal to the floor -- and repeated this 20 or 30 times -- I did this a few times over a period of days and the fault has never returned. Due to a house fire and the loss of a couple of cars I started using the Jaguar more a bit over two years ago -- Car now has 70k one it.

Unfortunately, for some reason Jaguar does not sell just the sensor -- only as part of the very expensive full Tbody. It's the TPS failure that necessitates the Tbody replacement. I have never seen any mention of a cross referenced part used on another car -- It's a part that does fail on other cars and is normally cheap and an easy fit.

The early non SC cars had a program to replace the Tbody. I forget what the problem was -- but the car would stall.

The Tbody either works or they don't -- I have heard of cars being sold (cheap) by owners not knowing that the Tbody could be fixed for a few hundred dollars + labor vs the 3k+ for the replacement.