I was just starting out when I received a 'check engine' light and a 'transmission service required' message on my 2001 S60 Volvo-auto transmission. The outside temperature as about 20 F. The road was a little slippery. The car has 169,000 miles. The transmission has 150,000 miles. The fluid was replaced at about 75,000 on the transmission.

My code reader shows codes of 'P1618-Fault in lead between AW50-52 and Motronic 4.3 (MIL requested)' and 'P0722 Output shaft speed sensor circuit no signal.'

The car seems to run okay. A couple of times I noticed possible rough shifting between 2nd and 3rd. However, it was difficult to tell. I drove 27 miles and it seemed fine. After work I drove 28 miles in several inches of snow at 20 to 30 mph and the car seemed to be okay.

Any suggestions?

 

Hey Mike!

So, I am having a very similar issue and I joined this forum to see if anyone has been having issues and it seems there are more questions than answers.

What ended up happening with your car? Any follow-up? My 2002 has 165,000 on the original transmission and I have the same check engine light and "transmission service required" message, but the car is driving just fine. I also live in a cold weather area.

Anyway, I'd love to know what happened in the end

Thanks!
Andrea

 

It turned out to be a simple problem. The output speed sensor on the transmission failed. What's interesting is that the failure was caused by rodents eating the wires from the sensor. They had made a nest on top of the transmission and decided to make a meal of the wire.

I removed the air cleaner assembly to gain access to the wires. I had to splice in about 6 inches of new wire. I reset the codes and the everything is fine. No problems.

 

hi, mikelakeville
I have the same codes on my volvo s80,
If you could tell me where is that speed sensor located!?

 

now if it's what I'm thinking of read this before you take out the sensor or you will break something and the only fix will be pulling the transmit ion out! seriously... I know cus I did it

now the sensor that determines speed in the transmit ion is called the Engine Crank Angle Sensor (now I might be talking about something different but I'm 90% sure its the same sensor)
its located right on top of the transmit ion under the air box and under the radiator hose that runs between the two you need to move it all out of the way

the sensor it fastened in a plastic mount which is in turn mounted to the engine block. if you simply try to remove the bolt from the sensor you will snap the bracket, so hold it in place very tightly perhaps even have a friend help but seriously be careful. there is no way to replace the bracket because part of the transmit ion covers one of the 2 bolts holding in into the engine block. reattaching it should be easier as it just floats above the hole in the transmit ion so it doesn't need to be super tight just enough so it doesn't fall out.
sometimes the sensor collects metal shavings from wear so clean it off then try it again before you actually replace the sensor.