Throttle body issues repair

I’ve been having an issue with my 2000 XK8 FHC. I keep getting intermittent problem codes. They designate issues with the throttle body. I did a web search and found a video on YouTube about the exact problem I am having. The video shows how to fix it. It also gives a referral to Automotive Scientific Inc. an Ebay company that does rebuilds of the throttle body. I am going to send my throttle body out next week to have it rebuilt. The turn around time is supposed to be under a week. I will update on the results. I also advise watching the You Tube video (Spa Guy) JaguarXK8 Fail Safe P0121 Code, How I repaired it. The video has numerous ata boy comments and thanks.

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Stephen we had same problem! Fail safe mode and drive car then have to pull of road let sit for a bit then go again intermittent! Probably tps might start with that but I found a car at kickball usa… Paid 100 bucks for used one but you need to buy mounting gasket cause it’s metal crush kind. Never had problem since been bout one year took bout your to replace! There pretty pricey 1500 dollars.

Used throttle body with all sensors.

The rebuild is going to be a little over $ 300.00 US with shipping from me to them. Shipping from them to me is included.
I am planning on doing a major maintenance upgrade this winter including all hoses. I discovered the heater hose under the intake when I pulled the TB. I am also a bit shocked at the cost of all the hoses. I am going to be doing new front springs, already did shocks. I am also going to check the tensioners and replace the thermostat housing, cross over pipe, water pump and anything else that is reachable while I have the intake off for the heater pipe. The car has a bit over 100,000 miles on it and is my daily driver in season so I want it tip top next year.

I had my X308 XJR throtlle body rebuilt by ASI and it worked well. Eliminated the fail-safe errors and the chopping of power which I thought was downright dangerous.

I preferred it to a used throttle body because who knows if the used throttle body is any better. I suspect more than one AJ-V8 powered jag has headed to the scrapyard because of the throttle body failing. Even if it works, who knows how much longer it will last. You get a warranty with the ASI unit, and they’ve been around for a while (they fixed mine 5 years ago, and they were already established even then.)


I’ve just finished installing the rebuilt throttle body. The entire project including replacing the coolant level sensor, set up, test drive and clean up took about one and a half an hours. I have not to this point had to adjust the throttle body. I followed the directions that came with the rebuilt unit and did the install. The test drive went fine and the car idles at about 600/650 RPM.
I do have an issue in that the coolant level low light is still on. The coolant is topped off so I know it isn’t low. Is there something else that is a common issue. ?

Hello Stephen - look at this Jaguar TSB referencing the low coolant light still on after topping off (I don’t know how to copy link so typing it) - so hope this helps - in short, it explains that the sensor gets stuck in the low position sometimes after getting low, thereby keeping the low coolant indicator light illuminated - Tex Terry II, 1991 XJS V12 Classic Coupe, 1986 XJS V12 Coupe - sent 7/10/2020 1311hrs. EDT USA.

Slight correction to post above about TSB - after the “www.” it should read “” not - sorry - Tex Terry, II 1991 XJS V12 Classic Coupe, 1986 XJS V12 Coupe - sent 7/10/2020 1333hrs. EDT USA.

I kind of thought that might be the issue. I bent a wire and tried to fiddle around inside the tank to free it up with no luck. I have bypassed the sensor for the time being just so I don’t have to look at the notice.
I just clay barred the car and gave it a polymer polishing. Damn, it looks great !!!