My 2000 XK8 (80,000 miles) was in storage all winter and refused to start this spring. It threw a code 1122. I also had some issues last year where the car would go into limp mode while driving. I simply turned off the car and restarting would fix things and I would be on my way, however, these incidents were increasing in frequency.

I searched threads on the forum and although the 1122 is related to the Throttle Position Sensor (TPS), there were some suggestions regarding some influence perhaps by the MAF sensor. So, I removed both connectors, cleaned them and and replaced them. Additionally, the MAF was cleaned. I then erased the codes and tried to restart. No luck, still 1122.

Should I replace the TPS? Should I also replace the MAFS? Replace connectors? (that might be messy)

These are pricey components but if these items wear out then I'm all for replacing them, but if they have no predictability then perhaps one at a time ???

I should add that the metal housing my TPS is connected to has a yellow chalk "X" on the top and the screws have paint on them to reveal removal. Maybe these were once recalled?

Also, I would greatly appreciate some recommended sources for parts - who are reliable suppliers with good prices ?

I've used some in the past - Motorcars LTD of Houston and Sports and Classic Cars of Houston, but only for small things such as filters.

Thank you.

 

Start here.

https://www.jaguarforums.com/forum/s...ad.php?t=30792

 

I've been through those steps - it's definately the TPS or MAFS - the 1122 code is a low voltage reading on one of the TPS connections. Just looking for similar experiences with the 1122 code - replace the TPS? replace the MAFS?

 

Have you tried cleaning the contacts and greasing them then reinstalling?

 

You may be correct that you have or had a problem with the TB but you may have two problems and the second one is that it will not start. Check your fuel and spark to be sure! You may need to look at the possibility other issues. Your car is a 2000 and I must assume Nikasil!
This might help on the TB http://www.jaytanindustriesinc.com/ you may want to check with them. I would suggest cleaning/changing the plugs first. http://www.gusglikas.com/AutoRepTB.htm

 

Actually, P1122 is "pedal position Circuit A low input". You are looking in the wrong place. Get the circuit tested to see if the low volatage is a problem in the pedal unit or the voltage supply to it. There may be a resisitve pin on the connector in the circuit or a damaged wire or connector..

 

Still unable to start with the P1122 code. So, I used electrical contact cleaner on all connections including all those plugging into the engine control module. Also applied some throttle body cleaner. (Noticed a shallow accumulation of oil in the bottom of the throttle body ????)

When done, the Jag fired to life with no codes. Finally success and no replacement of the TBS or MAFS. BTW, I called our Jaguar dealer for a price on the TBS and they won't sell that component alone - they will only sell the entire throttle body at great expense ($900).

 

$900 is cheap, and no, no separate TB components out there for sale/replacement.

The oil accumulation around the TB plate comes from the crankcase breather fed into the intake tube after the MAFS. Over time oil vapor and particulates accumulate around the TB plate rim as the largest volumes of crankcase vapors come on deceleration when the TB plate snaps shut. This is pretty normal.

Glad you're successful getting it running

 

Would you get any oil into the throttle body from the part load breather being blocked also?

 

Certainly, if the Part Load Breather was plugged, the only place that bypass combustion gases could go would be into the Full Load Breather and on to the Throttle Body.

 

That is the way I see it! The better question is how much is over the norm?.