Fluctuating idle/hunting on 1999 v70 T5

It could be other things such as a vacuum leak, but one thing to check is a free unofficial recall. There is a "service campaign" for the electronic throttle system (ETS) and electronic throttle module (ETM) where they actually load a new program that ignores errors by the ETM. If they need to replace the ETM, it covers that also. It is not techically a recall, but "VSC 155 service campaign". They fix the ETM/ETS for 10 years or 200,000 miles, whichever comes first. They also reimburse people for repairs they have already paid for. For more information call Volvo Customer Care Center at 800-458-1552 or the ETM HELP DESK at 866-637-3774.

Here is what the campaign covers:

"Electronic Throttle Module (ETM) failure may illuminate Electronic Throttle System (ETS) light or MIL. Symptoms may include, uneven engine idle, and/or "limp home mode" that could restrict vehicle speed to 10-30 miles per hour. Faults of the ETM are stored as DTCs in the ECM. If OBD II detects a fault that might increase emissions, the MIL is illuminated. Remedy: A software upgrade will be performed at the next service interval, and ETM warranty extended to 10 years or 200,000 miles, whichever comes first."

It basically covers S70, V70, V70 XC, C70, S80, and S60 from 1999 to

2002.

For more information check page 2 of:

I have a '01 V70 XC. My symptoms were:

1) The idle stumbled

2) The cruise control would reset and wouldn't work until you shut off the ignition and turned it back on.

3) Occasional dead throttle when starting from a stop.

It fixed all three. It runs like new and all they did was the software update.