See post #16 - what are the values?

That PDF doesn't look too relevant to your issues...

 

Flow chart for lean codes starts on page 10 of PDF.

 

I'll know fuel trim values Wednesday. Scheduled for more tests at shop. Thanks JagV8.

 

fuel trim: -7 @ idle and -19 @ 2500 RPM - short

 

Ok, since the car has no leaks and fuel system is fine, I did an experiment and swapped my 2003 XJ MAS into the XK. Drove it all day and no engine light or restricted mode. 4 test drives and no codes. I think I had a bad MAS. I'll order another one tomorrow for XJ.

 

Looks likely. Let us know...

 

When you replaced the MAS sensor did you use OEM or after market? I had an issue with the one from NAPA popping codes so I returned it and cleaned the old one again. No codes since.

 

Still no codes after a lot of driving. The CEL was popping only at idle. Fuel trims @ idle were only .2 difference than normal. I put the aftermarket MAS in when the codes started popping up a few weeks ago. It never occurred to me that the new MAS was bad too. So what's the deal? Do I have to buy an OEM sensor? It's $318 @ the Jag dealer. Seems silly that there wouldn't be a cheaper solution. The part I bought on Ebay referenced the exact part number on the original MAS. I contacted Ebay seller and he's willing to send another one but now I'm afraid to fit that part in the XJ. Right now I'm happy the XK is fine so i'm not going to mess with that one! This has been a total waste of time. Such a simple fix. I want to thank everyone again!!! Well, now it's on to getting the XJ back up and running. Hopefully not another saga like this one.

 

Sorry for late reply. I went through 3 of the replacement MAS sensors and all were the same. At idle issued codes and went away while driving. I got my money back and cleaned the old OEM sensor several times. Now no codes and all is well. I got my replacement at NAPA here. I think the manufacturers "think" because it fits it will work. Something in the software is different in the Jag.