Mine had a similar problem, after 200,000 miles. I changed the $10 air filter in the back for the hybrid air intake and fixed it.

 

Good call... Certainly worth a try. How many miles do you have on your FEH now?

 

Ill be turnng to 200k in about one month. Man, I can tell you some stories about hybrid repairs and dealer incompetence. However, for now, the issues you get with an aging battery pack are overheating so you need to scape all the bug guts off of the hybrid radiator, and replace that filter!

 

Wow... Great advice! When you're talking "radiator" I'm assuming you're talking about the front of the car. I usually blast that off with a pressure washer once a year anyway. If anything the car gets too much cooling in the winter time but I would imagine that the filter might need to be replaced now. It appears to be reasonably clean but I'm sure there's micro-dust that I can't see hampering the air flow. Thanks for the tips... It would be interesting to read some of your stories on repairs. If there are posts I can read I would appreciate the information. So far my FEH has been an excellent vehicle and I couldn't be happier. I'm just cresting the 120K mark now...

 

Had the same issue with the vehicle not going into EV mode. Dealer diagnosed it as a failed HV battery cooling fan and repaired it under warranty (the hybrid battery warranty - standard warranty was up at 36,000).

 

Update: After quite some time of driving the vehicle with no change of basic symptoms since i was active on this thread... I'm finally experiencing a much more consistent lack of ICE shut down at stops. The battery temp was at 91F when I finally shut off the vehicle this evening after not being able to get it to shut off for a full drive. This is the first time I've ever not been able to get the ICE to shut off for an extended period of time.

After some reading, it seems to be that the most common causes of this are a failed battery cooling fan, or a failed MECS pump. Are there any other known causes?

 

Those are the big two. If it is the fans (there are two), I hope you have less than 100,000 miles...even then, be prepared for a battle with the dealer.

 

No such luck... I have almost 140K on my FEH now. Update: (again) Yesterday I drove all day with no issues regarding EV mode. It behaved as expected - Or at least the same as it has been for quite some time now. I still suspect that the MECS pump may getting weak, or that I may have an intermittent battery fan issue. I have yet to see any indication that the diagnostic system is seeing anything out of parameters. No wrench light (that would indicate a problem with the blend door actuator), No warnings at all. Nothing indicates any problem with the system. Mileage seems to be normal as well. I've been monitoring the battery temperature with the SGII since this happened and so far it seems to be cooling just fine. If it gets over 90 degrees it doesn't stay there long.

Does anyone know for sure what the normal operating temperature of the battery should be? I've read that it should not be over 91 degrees F. That was definitely the case when I couldn't get the engine to shut down. I haven't seen temperatures that high since. When that happened, I was slowly driving around a neighborhood looking for an address, mostly in EV mode. This was on an 80 degree day of course. Even when I traveled home at speeds that should allow proper cooling of the battery, it didn't seem to be cooling properly and the ICE would not shut down (when it normally would) all the way home (about 15 miles).

 

I'm having this issue on my new-to-me 2008 Escape Hybrid. I've changed the HV air filter and I've also just today replaced a faulty rear blend door actuator after buying a ScanGauge II and checking some values. I felt pretty confident that the door was stuck open making the AC evaporator do double duty. I checked the lines running to the rear and they felt cold like it should and the cabin AC is plenty cold. I checked the MECS pump with the key on and engine off and it seems to be running fine every time I checked and the MeC always stays in the 90s to low 100s. I also checked that both the battery fans seem to be running while I had the rear housing apart replacing the blend door actuator. Outside air temps range from 70 F to 100 F over the last few weeks and EV works great when it's cooler but in the mid-day TAV's stay in the upper 90s cutting out EV. And this is where I'm at tonight.




This was after a few minutes cool down from a small loop around the neighborhood. Before the drive the TAV was reading 96.8 with a couple of hours cool down tonight. Well I look into the operation of the new blend door with the key on and the engine off AND running. It looks like this. Open



And the blend door looks like this with the key off. Closed



Which looks like the wrong way the blend door should operate according to the threads I've been reading about it. Am I correct in thinking this? I'm in a pretty rural area and there's not too many hybrid specialists around. Can anyone verify the operation of your blend door?

 

Your description is very much the same as they way mine is behaving. When I've had trouble with the ICE not shutting down, which is usually after at least 30 minutes of driving, The battery temperature is typically above 95 degrees. The other consistent behavior it exhibits is that the battery temp seems to stay high for the remainder of the drive. I've done drives where the battery temp starts out at 95 degrees and the temperature cools down during the drive, indicating that the cooling system is functioning properly. When the problem of the ICE not shutting down occurs, it always seems to be accompanied by higher battery temps that never cool down during the drive.

All of this seems to suggest some kind of failure, or at least intermittent failure in the HV battery cooling system. The big question is: How does one diagnose and pinpoint the problem? There seems to be no indication that the computer system sees anything that would generate a trouble code. Until the problem becomes more consistent, diagnosis seems like it will be difficult.

The last thing I want to do is bring this thing to a stealership and have them rape me for thousands of dollars; misdiagnose the problem and expect me to pay for their attempts at fixing it. This theme is all too common. I've had much better luck working on my own vehicles, even though it can be a long process with issues that are intermittent.