This past year my girlfriend had a family XJ8 given time her and after a few months of driving it the check engine light came on and the car would say “restricted performance.” The codes it is throwing out are P0172, P0175, P0332, P1000p. When it first did this I cleaned the MAF sensor by the air filter and it went away for a while. Today it started doing the same thing, and when I was on the highway it was shuttering at times when I accelerated. Almost like when a spark plug needs changed, but not quite that if that makes any sense? I’m wondering should I just change the sensor, or do you think based off the codes and the way the car was behaving it might be something else?

 

The P0172 and P0175 codes indicate rich mixture on both cylinder banks, and the P0332 code is for the knock sensor on the B bank. The 0332 code is causing the Restricted Performance and most likely the shuttering as the ECU will retard the spark advance when this code is present. The Restricted Performance limits the engine RPM to 3,000. The P1000 code is normal and indicates that the systems checks are not complete since the last memory rest; this will show whenever the battery is disconnected. It will show a P1111 code when the system checks are complete and all is well. I have attached the code chart for the '01 AJ27 engine, but I believe the codes are the same for all X308s. The chart gives the default action of the ECU and possible causes, so a good starting point for the trouble shooting. One thing that the chart doesn't tell you is that cleaning the connectors to the sensors is sometimes needed. I've fixed several problems by just pulling the connectors apart and spraying both sides with electrical cleaner, then a little brushing off of any debris with a nylon brush, then reconnect with some dielectric grease. I know that sounds a little weird, but it is a Jaguar ...

 

I tried to upload the shop manual, but for some reason the attachment wouldn't load. You can download it from the top portion of the forum.

 

My wife's 2001 XJ8 showed the same P0172/175 (rich both banks).
I watched the STFT and LTFT and the RESTRICTED PERFORMANCE triggered at -25.
Sometimes it took several days for the RP to trigger.
I cleaned the MAFS. (no change)
I replaced all 02 sensors with correct Denso parts. (no change)
I replaced the intake manifold complete with injectors from another engine. (no change)
I tried different MAFS from known good running (AJ27) cars and parts cars I have. (no change)
I finally bought a new WALKER MAFS from Rock Auto to see if it might help.
The cheap WALKER MAFS has been in the car for a few years now and is still working fine.

I have no idea why the MAFS from my 1999 and 2000 XJ8 as well as a few other cars did not cure the fault? (They don't trigger a fault in those cars)

 

Zach, what year is the car? 98?

 

Oh sorry! It’s a 2000

 

Do you have the ability to check fuel pressure? Maybe start by checking the vacuum line at the fuel pressure regulator to make sure it’s not kinked or disconnected.

 

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