Just a little Public Service Announcement concerning the "drive by wire" throttle body.

It gets quite dirty over time. That grime can, and will get bad enough to make it sticky, possibly in the closed position. When that happens, the big, Red light comes on and the throttle becomes non-responsive.

In my case, no faults are recorded.

The dealership will diagnose it as a bad throttle body. However, a good cleaning will likely help or eliminate the problem. I simply used spray cleaner and a toothbrush, along with a clean rag. It was sticky-dirty. After the cleaning, no more problems.

I did spray a bit of lube on the shaft also, just in case the shaft was binding.

 

It's a common problem on the XJs, I've had mine flameout on the highway 3 times due to a dirty throttle body.

 

We purchased a spray "throttle body cleaner" but not sure how to use it. Can anybody tell us how to access the throttle body. The friend who recommended the cleaner said there would be a "butterfly valve" where the air filter is located. We just replaced the air filter and do not see any butterfly valve. I think the throttle body is located in a different area (right rear?). The car in question is 2002 S Type 4.0. Thanks!