I'm in good company in this thread. My p0a7c code was coming after an hour driving in 80 degree weather. Then I swapped in a motorcraft MECS pump. Now I get the code after 15 mins of freeway driving after a cold start. It's a good thing I live in major city.
Wondering if we've ruled out a good vacuum filling being a partial solution to allow for more range at least.

 

what year is your car?

 

2009

 

Well the dealer just quoted me $900 saying the problem is the MECS pump I already replaced with a Fomoco OEM one. I'm going to talk to them tomorrow about assurances or are they going on a hunch.

 

The problem is not the MECS pump. It was the first thing I replaced and I can verify good function for both the original (mine's a '12 with the revised pump already standard) and new one. Also don't let them charge you that much - it's a very easy home job (30 minutes) and I think maybe a 100 dollar part?

I have done 2 vacuum fills - one specifically requested at the dealer (was the only thing I took it in for after swapping my MECS pump) and an another after buying my own kit to do a full coolant swap on both loops.

If there's bad flow in the MECS loop, it's gotta be a restriction somewhere else...but I seem to have plenty of flow rate and a very rapid Inverter Phase Temp drop when power demand is released, which would seem to indicate contact and flow are at least ok.

Still don't know what exactly is tripping the error as reported temps are always different when it happens....without knowing the problem component or sensing method, it's been very hard to trace any further. I might be at the point of peeling the cover off the inverter housing to see if there's crust or something built up on any components I can see in there (shrug).....otherwise I am currently ignoring it for lack of any corroborating evidence that a real overtemp problem exists (reported temps seem acceptable, outer casings cool enough to touch, no change in electrical system performance or gas mileage)

If you had them run diagnostic, see if you can get your dealer to speculate on the actual component tripping the error. That's kinda where I'm stuck

 

My problem is this is my 3rd pump in the 3 years I've had it. I couldn't drive longer than an hour on the highway with the previous pump after a year, went and got a Fomoco pump and that time went down to 20 mins!

At this point, without any clear information about what the issue is I'm done swapping in pumps. If I can get assurance from the dealer that if the new pump doesn't work they'll keep at it without any cost to me then I'll pay the $900. Just to be able to drive on the freeway again.

 

I'd be pretty surprised if they agreed to that... when you say "longer than an hour," are you getting the wrench light, or more significant warnings or 'stop safely now?"

I am wondering if you might originally have had one of the notoriously bad older pumps, fixed that with a new one, and are now in the same boat as the rest of us with mystery overheating component X

 

Did you ever get around to this? I would be very curious if you see differences. Your other temps look pretty consistent with mine, and since you are having the same issue, it'd be really handy to get a baseline from an FEH that isn't

My operating theories at this point are:
A. There is more of that yellow crust I saw on my inverter hose fitting on internal components/channels that is effectively slowing heat transfer enough for inverter phase temps to spike momentarily (mine change very rapidly and think it's likely the OBD poll rate is too slow to show it all)
2. This error is being generated incorrectly (bad temp reading or calculation)
D. deteriorated traction battery is pulling too much current to maintain State of Charge and overheating generator/phase components (which would be a bummer because the only way I can thinkg to confirm this is replacing the traction battery)

...Or I guess other wear/bearing problems in the transaxle or PTU that are inducing extra drivetrain drag. I do have bearing noise I need to rule out, but I believe it to be the right front wheel and just need to find the time to put in the Moog steering knuckle I've had for 2 months already....but I'd be surprised if that's it since I'm still getting higher MPG than I was before changing fluids and tires

 

Bumping this thread... Anyone get anywhere on this issue?

 

Anyone have any updates on this? I've talked to a handful of mechanics, including shops that work on hybrids. No definite direction so far. Chatted with a guy who has 4 2nd gen Ford Escapes. He told me that one of his four Escapes had the same issue. Wondering if that sample is indicative of the rate of the problem