Unregisterable, unsellable, all because of an elusive IAT CEL.

[AverageFiestaEnjoyer]

Hey guys, I have a small issue that has turned into a year long nightmare.


I have a 2016 Fiesta ST. The only mods are a ITG intake, Mishimoto Oil Seperator, TurboSmart Kompact BOV, MBRP exhaust, and a Cobb Accessport tune. Everything was running fine with these mods from January 2022 to April 2023. All except the BOV were from the previous owner.

I just moved to Atlanta from Connecticut and on the drive down my solid yellow CEL came on. The car still runs fine despite the CEL. The only noticeable difference is a slightly rough idle with more pops and backfires than it used to have.

It’s been 10 months and I can’t get the CEL go away. It’s preventing me from passing emissions, and thus preventing me from registering or selling the car. It’s also legally risky to drive now since it’s technically not registered correctly in the new state after so long. My ability to do anything with this car seems to all hinge on whether or not it will pass emissions, which is all being stopped by this pesky CEL.

My accessport says the CEL was from a code P0111 which is for the IAT (intake air temperature) sensor. I tried clearing codes, removing the tune and and resetting the ECU to stock. This didn’t work. I took it to Ford and they replaced my MAF sensor, which apparently contains the IAT. This also didn’t work in getting rid of the CEL and at this point Ford refused to work on my car any more, and just kept telling me the light is on because of “all the mods on the car.” I don’t really believe this since the car was fine before I moved down here, and I haven’t added any mods since.

As of now I still have the CEL and it has become a P0113 code for IAT Sensor 1 Circuit High.

Any input or advice on what the issue could be? Starting to get really stressed out about it and it’s making me hate my car.
Some have suggested wiring issues. I’ve tried unplugging and replugging but not sure what’s what or if I’m even doing it right.

Any advice helps. Also looking for a good shop to take it to for service in Atlanta, if anyone has any suggestions.

Thanks guys.

 

[AverageFiestaEnjoyer]

TLDR:
CEL for P0111 turned into P0113. Replaced MAF, reset codes, reset tune. No fix. Can’t pass emissions, so I can’t register or sell.

 

[Alkoran]

A dealer changed the MAF because of a code related to the IAT and without doing a proper diagnostic. Classic. I guess they didn't even took the time to measure the ohm of the iat sensor before trowing the new part in.Take your car to a mechanic who knows how to properly diagnose electrical problems. My bet is that you have something that cause a high resistance in the circuit (which is what the 113 code is telling you), either chaffed wire(s), bad pin connections, corrosion or anything else really (last cause would be a bad pcm but you need PROOF to rule that as the cause).

 

[AverageFiestaEnjoyer]

H

A dealer changed the MAF because of a code related to the IAT and without doing a proper diagnostic. Classic. I guess they didn't even took the time to measure the ohm of the iat sensor before trowing the new part in.Take your car to a mechanic who knows how to properly diagnose electrical problems. My bet is that you have something that cause a high resistance in the circuit (which is what the 113 code is telling you), either chaffed wire(s), bad pin connections, corrosion or anything else really (last cause would be a bad pcm but you need PROOF to rule that as the cause).

hmm ok. I guess I need to just ask around more and find someone who really knows what they’re doing? I’m really bad at mechanical stuff and don’t know much. I’m more just into driving. My cousin used to be my mechanic for 5 years and I trusted him with everything but now that I’m in a new city I have nobody.
Thank you for the advice Alkoran.

 

[AverageFiestaEnjoyer]

What is a PCM?

 

[Alkoran]

What is a PCM?

same thing as the ECU

 

[AverageFiestaEnjoyer]

same thing as the ECU

Gotcha thank you

 

[TyphoonFiST]

What is a PCM?

Powertrain Control Module* Engine Control Module

 

[TyphoonFiST]

What You need to do is revert back to stock and clear the code and see what happens*

 

[AverageFiestaEnjoyer]

What You need to do is revert back to stock and clear the code and see what happens*

Do you mean revert the whole car back to stock? Most of these mods were done by the previous owner so I don’t have the stock parts. Would need to buy all of the stuff and pay to have it all put back to stock.

 

[AverageFiestaEnjoyer]

Powertrain Control Module* Engine Control Module

Got it! Thank you Typhoon

 

[TyphoonFiST]

How is the IAT/MAF sensor connector? is there any corrosion at the connector? has the Evap. emission harness been changed over to the 14-15 model year version ? send pictures if possible. Is there a Local ST club in that state on Facebook? Id suggest joining one and the Fiesta ST group and finding another FiST owner near to help too .

 

[AverageFiestaEnjoyer]

How is the IAT/MAF sensor connector? is there any corrosion at the connector? has the Evap. emission harness been changed over to the 14-15 model year version ? send pictures if possible. Is there a Local ST club in that state on Facebook? Id suggest joining one and the Fiesta ST group and finding another FiST owner near to help too .

hey typhoon. I’m really bad with maintenance stuff so I’m not sure how to check the wiring, but I’ll post some pictures when I’m on break at work in a few minutes. I also have no idea what the evap emissions harness is. Is that something I can easily change myself? Also I will look into a local Facebook group! Thank you typhoon

 

[AverageFiestaEnjoyer]

Here’s the pics I managed to get of everything under the hood.

 

[AverageFiestaEnjoyer]

It’s kinda a mess in there and idk what any of it does tbh 💀

not sure if anyone can spot what could be causing the issue.
Thanks

 

[TyphoonFiST]

jPEG840* That connector is taped this concerns me and i see it tapped further back into the harness. Also the MAP tap shouldn't have a Zip tie on it either in jpeg834. Do you not have the stock airbox? when was the last time you Drained the OCC/ Oil Catch Can?

 

[AverageFiestaEnjoyer]

jPEG840* That connector is taped this concerns me and i see it tapped further back into the harness. Also the MAP tap shouldn't have a Zip tie on it either in jpeg834. Do you not have the stock airbox? when was the last time you Drained the OCC/ Oil Catch Can?

- I do not have the stock air box.
- I lost the screw that went in the MAF sensor so I zip tied it.
- I have not drained that catch can in over a year.

Do they sell replacement connectors like that taped one? If I got a new intake or a stock one, would it come with a new connector?
How often should I empty the catch can? I forgot that was even a thing until recently.

Sorry if I seem stupid with this stuff. 😣 I’m pretty new to car stuff in general, and my cousin used to do all the stuff for me until recently. I want to try to learn though.

 

[AverageFiestaEnjoyer]

Oh also by the way, I tried unplugging that connector from JPG0840, and the inside where the pins are was wet and oily. Is this normal?

 

[TyphoonFiST]

Oh also by the way, I tried unplugging that connector from JPG0840, and the inside where the pins are was wet and oily. Is this normal?

No that is NOT NORMAL* You can get a can of CRC electromotive Cleaner at just about any Autoparts store* Spray the CRC Cleaner Where the Oil is in the connector and the sensor itself* Let it evaporate and then plug it back in and clear the code in the ECM/PCM with the Cobb Ap3. Go on a test drive for 5-10 min to see if the code pops again. The OCC should be drained every oil change BTW*

 

[Alkoran]

The MAF connector taped with its wires is NOT a concern (picture 840). Its rather comforting because thats how it leaves the factory. I just took a look at mine, which never had anybody else but me working on it and its taped as well

Oily deposit in the connector tells me the last guy who went there put some dielectric grease or fluid. Also not really a concern, but if it makes you better, clean it with some electronic cleaner.