Almost a week ago as I was pulling away from the pumps after gassing up, she stumbles a bit. Never did she ever stumble. I put her in neutral and hit the gas to see how she'd respond. She cleared up, and off I went on the 40 mile commute to the office. Sometime during the trip the CEL and "Restricted Performance" lit up. "Restricted Performance" went away but returned, then disappeared again. That night the mechanic hooked her up to reveal: P0171 Bank One Lean. Possible causes: MAF, leak before the cats, fuel pressure regulator, and O2. We gave her a brief lookover, then he cleared the code. I searched the threads and found this code/issue. After driving a few hundred miles the CEL and "RP" returned. Tomorrow we'll clean the MAF sensor and check the new O2 sensors installed a few months ago. Any ideas/suggestions?

 

Since you don't have a P0174 with it, I'd concentrate on Bank 1 (whichever side THAT is) and any vacuum hoses that are specific to it. I had a similar experience with my wife's 3.0L but P0171/0174...every "so often." Cleaned MAF, no joy. Finally "solved" it by swapping the MAF with my daugher's 03 3.0L. If you have an ELM 327 or the AE tool..or any that will record data whilst running, try looking at fuel trims at idle and 2500, or for real giggles, take it for a drive and then plot load vs. fuel trims vs. rpm ...AE can be configured to do this for you...with the elm, you hafta be a bit of a spreadsheet geekoid to pull it off, but it can be done. At least I think those were the parameters - search for XJRGuy's fuel trims primer pdf on here...and you'll see some of the things it can tell you. Even so, I had one MAF on the 05 that was consistently reading higher airflows in similar conditions vs. the one on the 03...even when swapped to the other car...and considering similar conditions - which made it all the more puzzling....codes are coming from the O2 sensor's view of how much O2 is in the exhaust...so if the "bad" MAF was lying about high airflow, more fuel than necessary would be scheduled and I couldn't see how that could cause lean codes...in any case, it behaves on the 03 and the 05 is no longer throwing codes, either....

 

https://www.jaguarforums.com/forum/g...ed-quiz-49317/

Not a brilliant idea to clear the code until you find the cause but looks like you got away with it.

See if all the OBD monitors have set before doing anything else with OBD.

 

Going to clean the MAF and snoop around above and under the car tonight. Thanks guys.

 

Any update?

 

1 of the biggest lean code causes on the SC engines are the ducts from the blower to the intercoolers up on top. They actually are 2 piece and slide in/out. I would monitor short term fuel trim and spray with carb/brake cleaner if that or another area it the leaker, youll see it on fuel trims

 

Sorry guys. I failed to mention I have a Tues. appointment with the exhaust shop. They'll check underneath for pre-cat leaks (there is a sound indicative of an exhaust leak). The MAF will be cleaned. Thanks BRUTAL, I'll have the blower-intercooler gaskets checked too.