hello-getting a -40f on my scanner for the inlet air temp sensor reading. is this incorporated in the maf sensor? i can't find it anywhere on the inlet air tract. thank you. oh... the car is a 2009 ford escape limited w/3.0 duratec.

 

It is not part of the MAF sensor. Here is what the ambient air temperature sensor should look like which may help you recognize it. From its appearance, it looks like it could be screwed into the intake manifold.

https://www.rockauto.com/en/moreinfo...t=7000&jsn=520

 

Some late models combine the MAF with the IAT. The way you can tell is if the plug on the MAF sensor has 7 wires versus only 3.


Usually, when you get that -40 degree reading , there is an open circuit to or from the sensor

 

thank you for your replies. i'm not at the car right now, but i think it's got more than 3 wires coming from it. not an expensive replacement; still not happy to hear it probably is a broken wire/ open circuit. wife's car-she's not happy w/any light on her dash she hasn't seen before. more investigation is required. i guess a '-40f' reading would call for the fuel system to put extra in to make up for the heavier air charge?

 

Looking at an OEM MAF sensor (MOTORCRAFT AFLS131), there are five pins in its connection. You could always pull the intake snorkel off the airbox to see if your MAF sensor has a second filament wire.You might be able to see if its broken causing the open circuit or ohm it out if you can determine the pinouts..

 

good morning- the part # is 3L3A-12B579-BA on this MAF sensor. it has 6 pins and incorporates at least two resistors i can see. haven't been able to determine what pins relate to the inlet air temp sensor. i watched my scanner (-40f) while wiggling wires and got no changes i could see. hate to just do part replacements to diagnose.....but you know how that is.

 

well, replacing the maf sensor did NOT solve the problem. removed the loom casing back to the main loom located in the upper radiator support. pulled and wiggled and stretched the wires; no help there. surely the power going to the iat would not be fused?? any further help much appreciated.

 

If you do have the integrated MAF-IAT sensor ,If you get no difference when you run the engine with the MAF plug off, that to me would indicate a break in the signal wire of the IAT to the pcm. Don't forget you will now get a code because the MAF is disconnected and will need to be cleared.
Does your wiring to the MAF show a GREY and GREY/RED wire. The GREY/RED is the 5 volt reference wire from the PCM and the GREY is the ground wire, both are for the IAT sensor if incorporated.

This may be a little more involved if you don't have a wiring diagram or good voltage measuring equip and might be best if a qualified shop were to handle the job.

Something you might confirm, Check every fuse in the battery junction box that has a 10 amp rating. one of them provides the power for the IAT circuit in the PCM.

 

thank you so much for your response. no grey or grey/red wires to or from the maf sensor. green, black, lt. blue, yellow/black, yellow/brown, and purple. but i will be checking the fuses when it gets light in the morning. hopefully that will be my answer. in the midst of this i changed out the troublesome ignition switch; unplugged a lot of connectors around the steering wheel. that seemed to have gone ok.

 

well it was a no go on the 10 amp fuses under the hood. none were blown. will be backprobing the individual wires to the maf sensor and see what the voltage is on each one and report back. have been looking for a schematic for this problem, but have had no luck. rather be beat than take it to a tech; that being said, would probably be the easiest thing to do. car has been sitting overnight w/the battery disconnected, for whatever good that would do. again, thanks.