Hello, this is my first post. Hopefully I'm doing this correctly. I have a 2000 XJ8 with 54,000 miles. I bought it for $500.00. It had the trans stuck in 4th gear. I drove the car home like that at up to 70mph for 20 miles. I had the trans rebuilt. The trans shop took the car to his mechanic because he said it wouldn't go very well. Limp mode. I had the car towed home from the mechanic because now it wont run at all. The throttle seems to not have any power going to it among other codes. I am starting with P0197. Can anyone help me out with the power circuit that feeds the temp sender. I am reading .3v to ground at the connector with it unplugged. Thanks

 

Circuits etc on JagRepair.com - Jaguar Repair Information Resource

Limp mode etc is when the car is trying not to let you destroy something expensive like the engine. In this case a sensor means it cannot be sure so heads for engine safety.

 

You have an x308 series, you should post in the x308 XJ section to get the best responses for your vehicle: https://www.jaguarforums.com/forum/xj-xj8-xjr-x308-27/ Perhaps a moderator can move your post.

Typically Limp Home Mode is due to a failure of the throttle by wire (either TPS or APS), but not sure if an engine temp sensor would cause this on the older models. If you are only measuring 0.3v at the sensor V+ terminal you have a lost the 5v reference. I'm sure folks in the x308 section can provide wiring diagrams and info on tracing this wire. If there was a failure of a 5v sensor supply further back in the system, that would explain Limp Mode as other sensors will have lost functionality (but may not have set codes). Check ground and signal leads as well.