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unfortunately I do not have the actual fault codes but when the fault first happened it was after the MAP sensor had been replaced by an independent Jaguar dealer. His autologic box had diagnosed this was faulty so he replaced it.I then drove the car home about 15 miles and the restricted performance light came on so I took it back immediately and the autologic box indicated it was the MAF sensor on the B Bank. The garaged swapped it around and the car ran fine for a few weeks and eventually the fault came back with restricted performance indicated. Once again the fault code indicated the B bank sensor was faulty so it was thought to be a wiring fault. The dealer once again investigated and could find no fault. The car ran fine afterwards and I took it on a long run of 150 miles and 40 miles before I completed the journey it went into restricted performance after I floored the accelerator leaving a bridge toll. I took it back to the garage and the box said MAF circuit fault but could not see the individual sensors. Once again after investigation the car ran fine for 100 miles before it happened again. I had it trailer-ed back to the dealer who has been unable to identify the fault twice since. I will take it back again but suspect it is the same fault. I do not have a code reader at the moment but when I visited Gendan they tried their top of the range box on it and that too fail to identify the individual sensors but also indicated MAF circuit fault. The dealer has since tightened up the connectors but the fault has still remained. I have had the car from new in 2006 and until 4 years ago it was dealer serviced. It was recalled at about 2000 miles to have the turbos replaced by Jaguar and a couple of months out of warranty at 16000 miles it went into restricted performance mode. Jaguar read the fault codes p244B-00 and P2453-00. The info from the Jaguar approved dealer said:carried out checks and found oil level too high and NS port deactivation valve not holding pressure. Replaced port deactivation valve kit. They also gave me a booklet from Jaguar about looking after your DPF and enquired on my journeys which at the time was 10 miles to and from work including standing traffic at points. The commented that could be detrimental to the engine. Needless to say I knew nothing of this from the salesman. Recently the gearbox has been replaced because the coolant leaked in to the gearbox lubricant and destroyed it. Another Jaguar design fault I believe.
Happy New Year and many thanks for your answer. My main concern is the reliability of the restricted performance light coming on. When returning home from Christmas on mainly A roads with a couple of miles of dual carriageway the car goes into that mode within a 100 metres of the same spot. On motorways it takes a little bit longer but still predictable. It seems to me it is when the vehicle is fully warmed up. With a broken wire in my experience the fault would tend to come and go in the initial stages of failure. It may also be affected by movement of the loom caused by flexing of the vehicle body or the engine under load. If the car is left overnight or possibly shorter, the fault disappears and the fault is stored in the memory. I will have a poke around because according to the wiring diagrams 12V should be on pin 4 of the Maf sensors. I suspect this may be disappearing leading to the maf sensors not being seen by the diagnostic equipment. The only thing I see against this is the air intake sensor is incorporated into the MAF and I have not been made aware of an error with this.