So when I bought my car it had a check engine light on and read "restricted performance". I put it on the code reader and got something about the MAF sensor (P0101) and of course the system banks 1 & 2 too lean codes (P0171 and P0174) as well as P1000 (which I'm still unsure of). Anyway, I cleared the codes and the car runs 100% perfect until i shut it off and restart in which the check engine light and performance message pop back up and I have to do it all over again. i spent some time on this forum and found a few people with the exact same problem and codes and they each said they replaced the MAF and problem solved. I ordered a new one online but when I replaced the old one with it the car instantly got worse!! It would take two cranks before it would start and idle really rough and of course the check engine light and performance error came back on. I pulled it out and put the old one back in and the car is back to normal (but still throwing the same codes P1000, P0171 and P0174... The MAF code is random and I did see a strange ATTCP code a couple times).

Anyone else experience this? I'm wondering if I just got a bad replacement MAF...

 

Hi: I too suddenly had p0171 and restricted performance. I discovered weeks after the fact my local oil change shop had left my air intake open to atmosphere. My MAF sensor had melted itself trying to clean off dirt. The replacement one looks a bit different physically but seems to work OK in my car. Does your new MAF sensor look exactly like your old one or not? You say you are clearing your codes...how are you doing that? In the course of chasing my own problem, I am getting the idea that my problem and maybe yours too is an air leak in the intake system. Have you gone over your air path thoroughly? --Tom in AZ

 

Yes the two MAFs look almost identical except for the little green pin sticking down in my original MAF sits a little lower than the replacement.





I did go through the air system and retightened the clamps on everything and my air box was not completely/correctly locked into place either. So I fixed that too but it didn't seem to make a difference.

Originally on the left... New replacement on the right

 

P1000 is explained via Search / read workshop manual (free) / see codes PDF (also free). You want those items anyway.

I'd watch fuel trims. If you're getting codes like P0171 the trims are where to go.

 

Both my old and new MAFs had extended bulb similar to your old one, not your new one. FWIW, it seems odd that the bulb on your new one does not extend further into the airstream. My understanding of P1000 is that the ECM is still in "learn" mode. Some emissions stations will not allow a test if that code is present even though there might be no CEL. My car eventually did pass even though P1000 has not gone away. P1111 is the desired "background" code that indicates learning has completed and all is well. P1000 will set when battery cable is pulled off for any reason.

 

The thermistor exposed for view is the charge temperature sensor. As long as it is exposed, and you would want it clean of course.

 

I have my MAF cleaning spray ready to go and the Denso MAF on my desk, but where do I spray it? Down inside the little plastic tower? And the two little wires with the bulb is a thermister temperature sensor and not the hot wire MAF?

My thermister appears to have a little whisker of something stuck to one wire and I'll see if the spray knocks it off, but how do I make sure I have cleaned the MAF sensor itself?

BTW, I am cleaning it to see if it will lower my LTFTs which average 15 and 10 percent respectively on bank 1 and bank 2 at 50 MPH and level road.

Edit: OK. my bad, I got a flash light and I see those little wires way down (or up?) inside the plastic column now, so Ill spray away. The intake tube is very clean and I can feel nothing around inside the MAF hole with my fingers so this may be overkill, but the MAF is probably the original so it won't hurt to do it.

The whisker did come off the thermister. Bet it wouldn't hurt to clean the MAF on the Land Rover too.