CEL came on today, plugged in the scanner and got "P0101 - MAF or VAF A Circuit Range/Performance." This surprised me because I was pretty sure that the 4.0 doesn't use a MAF or VAF sensor. Is there one and I've just never noticed it or am I right in thinking this code should never be thrown?

 

Is the actual Chrysler definition for a p0101 that?

Its prolly the map sensor.

 

P0101 doesn't exist for a OBD II XJ. Some scanners/code readers must be programed to the vehicle they will be used on, i.e., the 2001 Jeep, and it sounds like that scanner/code reader wasn't.

Try a different scanner/code reader.

 

Or do the KOEO cycle to get the code on the dash. That is usually a lot more precise than a generic scanner.

 

Doesn't work on most OBD-II XJs I think a few '97s could

 

Really? I thought it worked on all of them. At least for me it has worked on all the OBD-II and OBD-I Jeeps I have looked at. Learned something new today.

 

Salad is correct. The ability to pull codes with the "key-on, key-off" technique went away sometime mid-1997 for the XJ.

If you do the key-on, key-off technique on post 97 models, all you get is a cluster self-test, but you won't get any codes.

 

Are you having a problem that you wanted to chase down (other than just a CEL)?

 

Ill try a different scanner, I've just got a really cheap $15 one from amazon so I'm not surprised haha. Thanks everyone

 

Well I had a p0301 so I replaced the plugs with NTK and all is well now, I went in to clear the code for that and it gave me the P0101 also so I was just wondering if my scanner sucks or I am an idiot. haha

 

Maybe that code reader doesn't know the difference between P0101 and P0201, which is #1 fuel injector control circuit open or shorted.

Clear all codes and drive it. If P0101 reappears, think P0201.

Get a new scanner if you have the bux, otherwise get a new code reader (OBD II is all you need, not OBD I and II, or CAN).