FORScan forum

I have a 2012 Fusion Hybrid. I live in TX and do a lot of high speed interstate driving, and so I get the P0A7C "Motor Electronics Over Temp" code and wrench light almost every day when driving at 75-80mph and when outside air temps are in the 80's or above (which is practically every month except Nov-Feb). No driveability concerns, just irritated that the light keeps coming on.

I used Forscan to scan the MECS_V PID to determine if the temperate of the MECS coolant was in fact going really high... turns out, its in the normal range even while the wrench light comes on and the code is set.
Supposedly the MECS coolant temp is not supposed to exceed 150F in "normal driving". I never even get close to that. In fact, the MECS temp values are higher when I'm NOT going at high speed, but they are higher when I'm going slower or stopped. I've already had the dealer replace the MECS pump for the newer style, and they don't know what's causing the wrench light. They said if I take it back in again, the only thing they can do is replace the entire engine/transaxle - at my cost, of course.

I've read that there are TSBs for earlier model fusions that address this issue.
Does anyone know what values they affect?
As far as the MECS pump goes, its either "on" or "off", and from documentation, its "on" anytime the key is on. Mine does not have any faults, and is always on like it should be.

I'm thinking there's some sort of a "temperature limit trigger" parameter in the PCM that needs to be adjusted higher, but not sure which - or even where to go to try and find out which parameter.

Any thoughts?
Thanks!

Sounds like the motor electronics module itself is over temp, and the MECS_V PID is reading the temp at the MECS pump. I would take that as an indication that the MECS pump is inoperable if they are separate units. Is there a separate PID for the temperature inside the motor electronics module?

I'll have to check the service information CD I have, but I believe that the MECS temp sensor is the only temp sensor in the MECS cooling circuit. It's already located directly in/on the electric motor, measuring the temp of the coolant at that point.

I'm thinking that the criteria is something to do with the relationship of the MECS_V temp sensor voltage related to the VREF voltage value, and maybe the problem is really with VREF?

Also of note, the coolant degas reservoir for the MECS doesn't even have a pressurized cap. When I stop the vehicle after driving it, its cool enough for me to open it and stick my finger in the coolant.

Same trouble wit Ford Escape Hybrid 2010MY.
Ran on the highway. The temperature in the street is 91-92F. Inside the machine, the temperature is 73-74F. The speed is 75 miles per hour. There was a wrench and error P0A7S. After that several times I saw this error, but only on the road and only in hot weather. Ford has a TSB, but only for Ford Fusion, Lincoln MKZ and Mercury Milan. I do not know if this can help.

Has anyone figured this out. I have the exact problem. Its fine around town but when im on the highway its coming up with the wrench and mecs is above temp. Then back to normal after shutting off.

Ha! I was just googling for this code again - because I'm still having it - and it seems to have finally progressed into a red triangle and 'stop safely now'.
Although that only happened once and a restart of the car cleared it.

No, no one has figured it out yet that I'm aware of...

Just checking in, anybody find a solution to this yet? I have a '10 Fusion Hybrid at 182,000 miles. I drive a lot of highway, and this seems to happen after drives of about an hour or more. If I drive hard enough, I get Stop Safely Now and have to pull over to reset the car.

While resetting my battery age last night, I ventured into the codes and freezeframe data for the MECS (but this is all from my memory). Evidently, the coolant temp was within reason at the time of the code, around 90C. But, inverter temp was a whopping 150C. My theory is that the MECS pump is in fact failing or failed, and not providing enough flow to keep the inverter cool during highway drives. This makes sense because the ECVT relies on MG1 at all times, especially on the highway, to control engine output. A lack of coolant flow on the highway would allow anything near the radiator to stay reasonably cool, but the inverter would be piping hot as it is the furthest heat source from the radiator, and the biggest.

Long story short, I'll test and probably replace my MECS pump and see where it goes from there. I should have instant results, as I can reliably replicate the condition on any drive longer than an hour.

Im having the same issue on a Ford Escape. Have you bleed the trans axle cooling system or tried changing the transmission fluid?
Here a link you my use
https://www.atsg.us/atsg/blog/fordescapehybrid2/

I've been having the same issue on my 2011 ever since I got it 3 years ago. Others on the Facebook Fusion Hybrid page are having the same issue.

Would be nice if Ford would issue a TSB after the 09/09/2010 build date, or if someone has a forscan fix for this.

wr400f250 wrote: Sat Oct 05, 2019 7:25 pm Just checking in, anybody find a solution to this yet? I have a '10 Fusion Hybrid at 182,000 miles. I drive a lot of highway, and this seems to happen after drives of about an hour or more. If I drive hard enough, I get Stop Safely Now and have to pull over to reset the car.

While resetting my battery age last night, I ventured into the codes and freezeframe data for the MECS (but this is all from my memory). Evidently, the coolant temp was within reason at the time of the code, around 90C. But, inverter temp was a whopping 150C. My theory is that the MECS pump is in fact failing or failed, and not providing enough flow to keep the inverter cool during highway drives. This makes sense because the ECVT relies on MG1 at all times, especially on the highway, to control engine output. A lack of coolant flow on the highway would allow anything near the radiator to stay reasonably cool, but the inverter would be piping hot as it is the furthest heat source from the radiator, and the biggest.

Long story short, I'll test and probably replace my MECS pump and see where it goes from there. I should have instant results, as I can reliably replicate the condition on any drive longer than an hour.

I've been having almost the same issue. I did have a broken axle 6 weeks ago but this red triangle began before that. Looking up P0A7C I found a page with this list of possible causes

Common Problems That Trigger the P0A7C Code
Converter failure
High voltage control module failure
Hybrid transaxle assembly failure
Motor electronics coolant temperature sensor failure

I'm probably going to replace the coolant pump as I've been told by two mechanics that could be the problem. If it helps I'll post a message. The issue that worries me is that I feel that the car lurches on the highway. It's not a really smooth ride. The roads here on Long Island aren't the greatest and on newly resurfaced pavement it does smooth out but I worry it could have something to do with the transaxle. With the broken axle in the recent past I'm not ruling it out. I wish I could diagnose it better. I'm just going to have to let a mechanic do it. Since it only happens on hot days with either long highway rides, driving over 50mph for more than 10min or constant stop and go in hot weather I think it's probably the coolant. I'll keep the form posted.