just reached 100,000 trouble free miles. when the car went into limp home mode. got the P0121 code. reset using a obd2 i keep in the car. 200 miles later does it again reset etc. Any ideas what could be causing this and any real fixes which do not involve jaguar dealerships?

 

TPS---(throttle position censer) fyi if the scanner didn't tell you. Could be drive motor or a broken wire, bad connection. It's a fly-by-wire system ,peddle sends a signal to the controller with tells a stepper motor how far and which way to move.Could be moisture in a connection. The motor is on the intake plentum RIGHT side as you stand in front.On the older cars I cleaned a reostat and checked them with a VOM but that was still a fisical linked system ,no luck here. Your scanner can read TPS position in % from idle. Check it w/o a code then with. No sense throwing parts at it. I do not know any specifics but mine runs about 9%@ idle. If you live in MPLS, MN the dealer will diagnose it FREE untill Jan 31, Just had mine done and was choked what they found. They estimated about $2654.00 plus futher testing @ $207.00/hr. I have nothing bad to say about them, there just to rich for my pocket book.

 

thanks for the reply. i pulled the airbox lid off and had a good look inside the tb. there must have been a good 1/2 inch of crud all around the butterfly. i cleaned it all off and cleaned all the electrical connectors. problem gone.

 

If the problem or any others return use some DIE-ELECTRIC grease after cleaning them if you haven't done so, seems that even with all the rubber boots and tight connections it still happens from within the connector, probably using dissimular metals with electricity, like a ANODE rod in a water heater.