P1121 Throttle Body: Accelerator demand sensor A circuit range/performance

[saajaguarxk]

While driving on the highway (4 lane divided U.S.) my MY 99 XK8 went into safe mode as I slowed to merge on to the exit ramp. There was a hard downshift followed by the following additional indications on the dash panel. Traction Control Failure, Restricted Performance, Stability Control Failure, Transmission Fault, Fail safe engine mode. When I got the car home I retrieved the following codes: Air Related - P0102 (Mass or volume air flow circuit low input), Intake Air Temperature -P0112 (Intake Air Temperature sensor 1 circuit low input), Throttle Body - P1121 (Accelerator demand sensor A circuit range/performance). Went through all the pinpoint tests identified in On-Board Diagnostics manual and Electrical Guide. All checked out OK. Both Service Bulletins 303-5498 (not needed) & 303-58 (Connector Material Mismatch) had been worked several years ago. I worked through all of the pinpoint tests referenced in the Jaguar On-Board Diagnostics manual and found all tests OK.   I visually checked the throttle cable at the throttle position sensor and found iit slightly soft. It wasn't droopy, just soft when pressed with a finger. I adjusted the throttle cable at the throttle position sensor at the throttle body 1 turn tighten. Erased all error codes. Car has operated normally. I hope this is the answer. 

 

[StuartXKR]

Sorry but I think you need a new throttle position sensor as this is a classic fault. The track on the sensor wares and you get this fault up randomly. It will get more often as the wear gets worse. Change the sensor and it will be OK.