Hello fellow XJR owners. So here is the scoop... Last week I had my Throttle Body ($2300) replaced after it failed (Engine Failsafe Mode) at 2 in the morning while coming back from Jacksonville FL. Well this week after coming back from Jacksonville FL the Check Engine Light came on. I took the car back to Buckhead Imports for a OBD scan and the codes came up the same (P1121/P1111/P1316) when the Throttle Body failed. So what they've decided to do is a Hard Reset. What is a Hard Reset?

 

This is a five minute or so job. Jaguars are computer controlled to a surprising degree, and a hard reset is like doing a CTRL_ALT_DEL on a PC. You do it by taking the cover panel off the battery, unscrewing the negative cable from the battery (not from the car body!) and holding the just-unfastened end of the negative cable against the positive battery terminal. Be sure you understand this - you DON'T want to short out the battery by mistake!

 

I wish you well but that is probably not going to fix it.

Let us know.

 

P1121 is Pedal Position Sensor range error - bad sensor or intermittent connection in connector... same kind of symptoms as when Throttle Body signals fail, but in a different place... can you get some recompense for their repair that wasn't necessary?

 

Well the part about taking the negative cable off of the battery negative post is a start, but then you go and turn the key to the "On" position and then you touch the negative clamp to the positive clamp. Otherwise a whole lot of stuff doesn't get put back to default.

P1316 means "MISFIRE RATE EXCEEDS EMISSIONS."
P1111 just means that the emissions system has passed its tests.

 

And like quad said p1121 is the gas pedal sensor(replace the gas pedal assembly), not the throttle body