So I did a dumb thing before going through emissions. I had the P0101 coming up and I would just clear it as the car runs awesome and actually gets 29 mpg on the freeway , idles great and no complaints. I would clear the code and it would be about a few days to come on so ..... I cleared the code, went through emissions and failed. (Yep, I wasn't thinking). OBDII not ready. So I order a new MAF and got it installed and checked out the computer for over 8 days and no codes except P1000 which is OBDII not ready yet all sensors were reading ready and OK except "Comp. not ready". Then a couple days ago I checked out the reading and the MAF came up but didn't light up the MIL/Check engine light. So I get back home and the MAF code is gone again. Phew!!!! So now I drive it up to Canada on a 3 day permit and all is good except code P1000 is still on. OBDII not ready. This has been going on for at least 30 starts and full drive cycles. When I drive back home, 130 miles non stop I check to see if the OBDII is ready. Nope still not but theres the MAF in the background but didn't light the MIL/check engine. On my way home I told my wife to fire up the car before I got there as I drive a Van to work and let it idle for at least 20 minutes and I will take it for another drive when I get home. Figuring that maybe I didn't idle long enough in the week and a half and over 600 miles driving. I get to the freeway and F#$@!!!! The check engine light is lit and there are 2 codes. Well low and behold the OBDII is now ready with a P1111 but the infamous P0101 is back lit!!!!! Help!!!! Also my MAF is at about .76 at idle and does a smooth scale up to 4000 rpm. My Long term trim and short term trim are a bit weird. At idle the short term is around 0-2+but the long term is about 8 on bank 1 and 5 on bank 2. Any help!!!!! The next thing I will have to do is pay a Mechanic to write me a bill and get a waiver which sucks as I don't like Check engine lights. It runs great and gets good mileage and hauls azz!! . What is going on!!!!

 

What make etc is the new MAF (it sounds marginally wrong)? Exact OE kind?

Have you checked its wiring etc?

 

Welcome to the forum Sixt8bird,

I've moved this second question of yours from General Tech Help to X350 forum. This is the place to post tech questions about your model.

Please follow this link New Member Area - Intro a MUST - Jaguar Forums - Jaguar Enthusiasts Forum to the New Member Area - Intro a MUST forum and post some info about yourself and your vehicle for all members to see. In return you'll get a proper welcome and some useful advice about posting to the forum.

Graham

 

It is a C2C7636 Denso. Quality OE replacement. The connections are all good at the MAF . Air box is good and tight. Air tract to throttle body is good with no leaks.

 

Next is probably dubious wiring - including ground.

 

I've become convinced that the recent P0101 code that my 2004 XJ8 was posting was due to a dirty EGR valve that was not behaving itself. No re-occurrence of the code since cleaning the EGR by using a dremel tool with a small wire brush attachment to reach inside the ports and then blowing out with compressed air, and checking that the valve was free to move.