P0705 / P1618 codes lit up:
 

My wife drives the S40 and came home today complaining that it was "acting funny". Knowing that meant trouble, I went out to look at it and saw the transmission light blinking and the check engine light on.

She told me it was idling low when she started it and sometimes while trying to accellerate on the drive home, it would lose power and just idle.

We had this problem last year and took it to the volvo dealership. After replacing both coils, everything seemed ok and we had no more problems this winter.

I drove it around the block and didn't notice the issue she was describing, so I checked the codes. P0705 and P1618 were in there, so it certainly sounds like a transmission sensor.

Can anyone more knowledgeable than myself lend their diagnosis abilities here? I'm happy to do some work on my own (sounds like this is a sensor I can replace myself, though I'm not certain if it's touchy to adjust), so if taking it to a dealer is smarter, I'm ok with that.

RE: P0705 / P1618 codes lit up:
 

I would erase the codes first. Then drive the car to see if they come back. I've had the "flashing transmission light of death" before and it was because I ran the car in gear while it was up on jackstands. Your wife may have just spun the tires too much.

RE: P0705 / P1618 codes lit up:
 

Yeah, the car behaved fine today, but this is the same issue we were having last summer (and some of the winter). Every once in a while (usually three or four times a week), the car would simply lose power and engine codes would start flashing.

I'm ok with generally clearing the codes for now and seeing how long it takes to happen again, but I'm more interested in what the problem might be that keeps causing this issue.

RE: P0705 / P1618 codes lit up:
 

I'm with you. I wish a car would either break and get it over with so I can fix it or stop the problem altogether. Intermittant problems are a PITA.

RE: P0705 / P1618 codes lit up:
 

It sounds like the trans is going into limp home mode, depending on the severity of the code it will start out in 3rd gear to protect the trans from overheating, you dont want to keep resetting the computer.

Had identical problem out of the blue. Cleared the flashing yellow arrow by opening and shutting the fuel filler cap.