Got a weird one. Got the IMA, charge and check engine light (the big 3) but the car was still running flawlessly. If I hadn't looked down at my dashboard, I would never have known anything was wrong with the car.

After stopping the car and restarting, only the check engine light was on. Again the car was still running flawlessly. Charging, IMA assist, everything just fine. After 4 starts, the check engine light goes away and the car is back to normal in every way.

This normality lasts for about 4 days and the whole cycle started over. This has happened 3 times. At no time has the car exhibited any signs at all of running at anything less than peak performance. Even the gas mileage has stayed about the same.

The codes I get are...

U0110 - F-CAN malfunction (Motor Control Module (MCM) Internal Circuit Malfunction)

U1201 - IMA-CAN MALFUNCTION (MCM (MOTOR CONTROL CPU) - PCM)

I've looked through several forums and nobody has ever mentioned a code starting with a U, let alone these specific ones...

 

I had those three lights come on once. Appears to be for no reason. After stopping and restarting, they went away. Took it to the dealer. They checked the car over and said everything looked good. They think it was due to bad gas making the sensors interpret funny readings and throwing the fault codes. In fact, I had previously filled up at a no name brand gas pump in the middle of the AZ desert. So it seemed plausible. I've never had those lights come back on again.

 

HA! That's exactly what I've been telling my wife, but she was skeptical.... Score one for our side.

I owe you one...

 

The thread I started about that problem is buried somewhere here in the HAH area. I don't remember where I filled up, but I was driving from Phoenix to Vegas. Got past the Hoover Dam, and as I was ascending up the mountain north of the dam, the car suddenly got very sluggish and the dash lit up like a Christmas tree. I was able to keep the car going at about 50-60 MPH, but pushing it faster than that took almost full throttle. It was something like 4 AM and I didn't want to stop along the side of the highway, so kept going to my final destination in downtown Vegas. I shut the car down, went inside, and about 15-20 mins later I came back out and started her back up to drive to the dealership. The car started right up and not a single light was lit on the dash. I drove the car to the dealer and it drove normally. When the dealer opened up, they took it right in and hooked it up to their computers. They didn't find a single thing wrong with it. No codes were stored at all. From what I described, they thought it was bad gas throwing off the sensors on the engine. The engine didn't know what was wrong, and went into sort of a "limp mode" where the car's parameters are set at a much more conservative setting, so the car could be driven safely without further damaging the engine.

 

Mine happened more than just the once, but the symptoms themselves were virtually identical. I filled up at a local Wawa, and shortly thereafter started the cycle I described above.

As soon as I had used up that tank and refilled, the car went back to normal and hasn't had a problem since...

 

Well crap. It's back. And it appears to be getting worse. Honda dealer here I come...

 

So I took my 05 to the Honda dealer, and this one you are not gonna believe. I spent about 48 hours wringing my hands and became absolutely convinced I was gonna have to write a check for like $3000 to fix the problem.

Then the dealer called and said that after they pulled 8 (yes 8!!) codes from my computer, they tracked the problem down to a faulty ground wire.

Apparently when the battery was replaced a couple months ago, one of the ground wires was improperly attached. The intermittent interruption of electricity was throwing all sorts of random codes and putting my car in limp mode.

Total cost to fix? $90.68. Basically one hour of diagnostic time. I swear I nearly kissed the tech...

 

Do you mean 12V battery?

 

Yeah, the 12V car battery.