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2014 Ford Fiesta SE with check engine light on with error code P090C - Help fixing this issue

joeym32

New Member
Messages
1
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0
City
Macon
State
GA
Country
United States
What I Drive
2014 Ford Fiesta SE
#1
My car started throwing this error code at me suddenly about a month or so ago while I was driving on the interstate. My car was having difficulty revving up, going to about 4-6000 RPMs just to shift through the first few gears. That was about all the problem was, occasionally revving up a lot with difficulties switching gears.

I had to fly out that day so I couldn't get it checked that day. When I got back, the code reader at the auto parts store didn't even read a code even though the light was on. While driving home it started acting up again. I've got a code reader and it had the code P090C, which has been incredibly difficult to google a solution for (for fiestas at least).

If I clear the code, the car drives fine - but sometimes it'll start acting up again without any discernible pattern. Now, it happens just about every time I drive. I'm not very good with cars at all, so I don't have any idea what to even do.
Does anyone have any solutions, how-tos, etc?
 

LionsTooth

Senior Member
Messages
377
Likes
455
City
Northern
State
CA
Country
United States
What I Drive
2015 Fiesta SE HB Magnetic
#2
My car started throwing this error code at me suddenly about a month or so ago while I was driving on the interstate. My car was having difficulty revving up, going to about 4-6000 RPMs just to shift through the first few gears. That was about all the problem was, occasionally revving up a lot with difficulties switching gears. I had to fly out that day so I couldn't get it checked that day. When I got back, the code reader at the auto parts store didn't even read a code even though the light was on. While driving home it started acting up again. I've got a code reader and it had the code P090C, which has been incredibly difficult to google a solution for (for fiestas at least). If I clear the code, the car drives fine - but sometimes it'll start acting up again without any discernible pattern. Now, it happens just about every time I drive. I'm not very good with cars at all, so I don't have any idea what to even do.
Does anyone have any solutions, how-tos, etc?
There's some info and threads, here. Looks like a TCM issue.
 
Messages
230
Likes
200
City
Grand Rapids
State
MI
Country
United States
What I Drive
2019 Ford Fiesta SE HB
#3
Well, here's what I got...

1620143745263.png
Ok, so you may not be the best at cars, but this tells me you have a potentially big electrical problem that could damage the powertrain.

Hall effect devices are simple field proximity switches, they work like a switch; off when not exposed to a magnetic field - turn on when exposed, and if left exposed - will "neutralize" or switch off until the field is removed then switch back on erratically during that transition. They have a memory effect especially when they get coated in debris as small as metal filings and shards that have or are (exposed to get) magnetized themselves - they tend to stick to the metal mount of the sensor - lowering/lessening the ability to sense changes they need to - in order to work to correctly time the shift points.

GM HEI stuff from years ago had a similar problem with Reluctor to Sensor - a stationary sensor housed surrounding a moving coil - similar to an Alternators stator and Rotor - a simple air gap can get clogged by metal shards and cause intermittent to eventual failure of the pickup coil to even fire the spark plugs. It didn't fail itself, it just can sense the change in the field thru the air gap that gets clogged with debris.

I know, you're not "into" the tech of cars, but it looks to me that the devices used in the shift housing that contains the transmission and clutch - for that year, needs some work. The clutch and gear train in the area can "grind" or wear, causing small shards to appear and due to their size and weight - fly about and ricochet inside the housing - even getting lodged into the wiring harness and or mounts these devices use to maintain their firm distance for gap and to reduce vibration. Even then - a loose mounting can also cause this failure because the device itself can sense the vibration as a change in the "stationary" field around it. (the Hall effect device moves within it causing the error to appear)

Since you're telling us the condition seems to be getting worse, the only help I can provide is to brace for a large bill for the labor cost and teardown and reassembly is time consuming. There is an ongoing litigation suit for repair and if this failure is part of the conditions of the lawsuit - you may get a break off the cost of the repair.

No guarantees...
 

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