I have an 1998 XJ8 VDP with an intermittent problem in colder weather. When the temperature is less than 60 degrees it will start fine and then
I get a restricted performance message. My code reader shows P1000 and note "Control Unit 11". I can clear the code and the car drives fine.
On warm days it does not show up at all. Once the engine is warm, I can shut it off and restart and the restricted performance clears. In restricted
performance I have power, but the throttle is not smooth at all. Does anyone have any ideas? I don't have any other codes.
Thanks

 

I would head to the nearest auto parts store that offers it and have a battery load test done. Cold weather codes and none with warm weather signals a failing battery.

 

The P1000 code simply means you have cleared any existing error codes, and the computer is going through its standard cycle of checking to see if anything else is still wrong.

Your "restricted performance" error message should have a code associated with it (you may have already "cleared" it?)

I don't know what "Control Unit 11" code means, maybe other more knowledgeable forum members will chime in?

My best bet considering your problem of when it is "cold", and not so much when it is warm, would point to the solder joints on the ABS module, but that is only an uneducated guess on my part. Or as forum member avern1 suggests, it could be a sign of a failing battery, these cars are very susceptible to low battery voltage/amperage.

CK.

 

Put a heated blanket under the hood as the easiest, cheapest and quickest repair method?? 🤷🏼🤷🏼🤷🏼

 

This sounds like a cracked knock sensor. If it chugs in Restricted Performance when you try to accelerate, I'd be looking at that.

 

Clearing the codes also clears all the OBD monitors and that sets P1000 for as long as they take to set again (if they do).

Each unset monitor prevents a slew of codes from flagging because the car just cannot tell what's going on.

You may now be in Catch-22 where some fault(s) is/are stopping the monitor(s) setting thus preventing codes being flagged.

You can check which monitor(s) is/are unset to get a clue about what may be wrong and could read live data for clues but beyond that you may have to guess and change parts in hope of getting lucky.

 

Thanks for the ideas. I checked a little more carefully. It is the Amber "Failsafe Engine Mode". I have been using an ELM 327 OBD2 reader.
Even with the light on I was only getting the P1000 code.
I ordered an iCarsoft LR V3.0 so I can get Jaguar specific information.

During today's drive it came on right after going over a bump in the road. It cleared itself after shutting it down and restarting.

Looking through the forum I found an old thread that had the following.... Brake switch sprayed with WD40, Replaced air cleaner, Cleaned throttle body and MAF.
Their problem went away. I'll start on that list while waiting for my new OBD2 reader to arrive.

 

My iCarsoft LR V3.0 Code reader came today. I was able to get P1221 and P1222 both Pedal position faults. I ordered a new throttle position sensor
PN 198500-3250 for $11.62 on ebay. Hopefully that fixes it.

 

I suspect Pedal means the Pedal (not the throttle sensor)