My 1999 XK8 battery drained down and my problems started. Installed new battery and car went into limp mode with code P1122 and an occasional P1121.
I’ve tried erasing the codes, but no luck. Did hard reboots and still there.
sprayed contact cleaner on TPS plug and the electrical connector just above the TPS plug, wasn’t sure if it was related to TPS electrical but was easy to do.

Any suggestions would be appreciated.

 

My car is a 2000 XK8 so we have the same engine and fuel delivery system, Denso. I had the same error and my car .It went into "limp" mode and had a check engine light. I had my throttle body rebuit and that solved the problem. A new TB is around $1600 but you can get yours rebuit for around $350. Also you can buy the TB parts, they are all Denso.
As you have a new battery and the connections are all clean it seems you have covered that possibility. The only other electical issue I can think of would be your atternator failing but you would be getting error messages and the AMP guage would show it.
Good luck.

 

Info from TSBs.

 

Before doing a rebuild I’d like to figure out why I can’t erase the P1122 code. Can understand If everything is reset and I start and P1122 code returns and goes back into limp mode.

 

Codes flag to show a fault. A code clear is a waste of time without a fault fix.

Of course it just re-flags!

 

If the PPS circuit is faulty (poor connection, faulty PPS sensor, bad wiring etc.) then it is a HARD FAULT.
Clearing it and it recurs immediately means it is NOT intermittent, it is PERMANENT.
DTC guide for you!!!

These are some TSBs issued when we had to deal with this years ago.

 

Motorcarman - Makes a lot of sense, mine is not intermittent. I haven’t done anything on the cable side of the TB. I’m not sure what the PPS looks like, but I’ll at least clean the injectors on that side of the TB tomorrow. Maybe just a bad PPS…

 

Hi - perhaps this article from member Gus will help you to identify things. See the second picture:
JagRepair.com - Jaguar Repair Information Resource

The PPS is on the LHS in the picture, adjacent to where the throttle cable attaches: - not the sensor with the red label.
See also illustration #10 in the TSB 303-S498 linked in motorcarman's post

 

After having a low or disconnected batter (and I've had both) I've seen all kinds of ghost codes that either disappeared just leaving/having a good batter connected over night, problem gone at next start, and/or some after driving a bit. For some reason, especially with knock sensors and codes for the TPS, once. They kinda "solve" themselves.

If the problem started in conjunction with a low battery I might think about taking my time and seeing what happens.

A hard reset, letting the car go to sleep, fully cool, or driving it and letting it go to sleep (even after a limp mode event) might help here. Maybe.

There seems to be a connection between the low battery and the code. No?

 

As an update to my P1122 code:
Had the throttle Body rebuilt by ASI
Replaced the PPS connector

Reassembled and all seems to be good.
Appears the main problem may have really been low voltage to the PPS.

While replacing the plug I noticed a crack to the insulation of the blue wire.

 

Glad that things have cleared up. ASI gives a one year warranty so keep your paperwork, just in case.

 

There are several ASI auto repair places on the Web. Does anyone have their contact info?

Like others, I'm having issues with my 2000 Super 8 going into Limp Mode.
I used to be able to turn the car off and then on a few times and then drive without issues until the next day.
Current codes are P1121 and P1122.
I've swapped out my TPS with used ones from otherwise working cars.
(With the only new replacements coming from China, I thought a used DENSO TPS would be a better choice.)

PS
Regarding TSB 303-58: Replacing TPS wires and contacts with gold plated wires and contacts.
Instead of cutting the wires and splicing in the new wires (which I have no way of finding), I bought a small gold plating kit from eBay: Solution and voltage source with clips.
The connector on the harness that connects to the TPS comes apart very easily (remove plastic positioner - mine was yellow; then, slide eyeglass flat head screwdriver between retaining clip and female contact; and pull wire and water sealing plug out).
Then, I dipped the contact into the gold plating solution with a small electrical charge and in 60 seconds, you have gold plated leads.

But, this did not solve my problem. So, off to ASI I need to go.

 

Per my notes in January 2013, the phone number for ASI (Automotive Scientific Inc.) in Tennessee was (866) 983-6688 and the website was www.autoecu.com.

 

Thank you for the reminder.

PS
I need to run the car a few more weeks before I can give it the All Clear, but…..

Gold Tinning the leads was much easier than expected and addresses a know dissimilar metal issue with the TPS gold leads and connectors leads.

It was pointed out to me that the Throttle Body itself is not likely to have gone bad, but the sensors have issues.
Since Denso sensors are not available, perhaps the aftermarket sensors are not gold plated.