Over the last couple of months I have been reading all the posts regarding MIL P0172...P0175...My issue now going on for just about 12 months and 10k miles I have todate replaced..(1) both up sream 02 sensor, 1 down stream..no fix, fuel presure reg no fix...temp sensor..no fix...MAS with jaguar part) no fix....cleaned Throttle Body and all interconnect lines, pipes, hoses, new air filter(nothing wrong with the old one) 8 new spark plugs no fix..cleaned all plug in pin connectors, no fix Now the car runs great, I would always get 19.5 to 22.5 mpg,street/f/way.. but the more I replace the lower the MPG now down to 17.1 Car runs great, no hard start, no stalling, easy cold start, perfect idle(650) I can go for a day or two, and 50 miles or upto a month or so and 500 miles before It codes..always the same P0172 and 175, with a P1111 ? now get this, car just passed Ca. smog no problem HELP I'm at the end?? as my friend Willie S once said, Death Where Is Thy sting?? CM

 

CM777 One other thing...I have owned the car two years, alway ran GREAT..T/Chain started to rattle, had the fixd both upper and lower...This Issue started right after that? I'm not sure how It could be related, But what do I know?? Thanks again

 

This issue can be caused by the pins on the MAF sensor not making proper contact with the connector-not because of any dirt on the connectors, but because the actual pin alignment causes intermittent connections at the MAF.

It's possible that when the timing chains were done & the air inlet trunking removed, that the previous stable connection at the MAF was disturbed & is now intermittent.

It may be worth bending the pins at the MAF connector slightly to give them better contact with the MAF sensor-this was the solution for one XJ8 owner who had persistent intertmittent P0172 & P0175 fault codes appearing.

The fault is common to both banks of cylinders, so it will be something like the MAF sensor signal becoming intermittent.The problem may simply be that the pins on the MAF connector plug need bending slightly to make stronger contact with the MAF.

The intermittent nature of the problem means it's almost certainly electrical in nature & from a sensor common to both cylinder banks, as you're getting both LH & RH bank fault codes.

 

Red October, Thanks for the tip, I have made sure the plugs In's are tight and secure and they do feel good, I do understand what you're saying..had one guy say Throttel Position sensor? another say ECM??...I will try bending the pins a tad...Thanks for the tip..CM

 

This is the link to the article with the same fault as yours:

Running Rich - P0172 & P0175 | Jeeves and the Jaguar

Whilst the plugs may feel nice & tight from the outside, the problem this guy had was the pins on the MAF themselves not being in ideal alignment with the connector pins. So he just slightly bent the pins on the MAF sensor to make a more positive contact with the connector pins & the fault was then cured...

 

I must admit I did not believe it could be that simple, whenever does it cost nothing to fix a Jag. I figured I would try the bending of the pins on the MAF before I ordered a new MAF. It worked, thanks for saving me $250