so i washed my s80 today after about 10 days of ownership. i cleaned the engine because it was dirty. drove it home and then to play a pick up game of basketball. when i was driving home from ball the idle problem started, and the check engine light came on. the on-board computer doesnt give me any errors.

what could be the cause of this? i read in the owners manual to check the spark plugs to see if water got down in there. could that be it? if so would i just need to wait for that to dry out?

i found this post from a couple years ago: https://volvoforums.com/m_29393/tm.htm

yes the light flashes when i drive but not in idle.

 

DONT DRIVE THE VEHICLE WHEN THE LIGHT FLASHES!!!! when the engine light is just on it is letting you know something is wrong as far as emission control, your vehicle is not going to run efficiently. but when the light is flashing, there is a catalyst damaging misfire occuring. the more you drive it while the light is flashing the more chance you have of melting your catalyst and having to spend 1 to 2 thousand bucks at a dealership (not sure the exact prices of catalysts on the s80)... if it is an ignition misfire you are pretty much dumping raw fuel in your exhaust, which will ruin a catalyst. check your plugs for water and repair as necessary, but if you are not mechanicly adept get it to the dealer asap..

ps.. please dont drive with that light flashing..

 

its not a constant flash. it only flashed about 5 times. luckily i didnt have to drive that far. only down the street. about 1/10 of a mile. mind you, this only happened after i washed the engine bay. which seems to parallel the post from the link i gave, except he was driving in the rain.

i started the car today. the idle is where it seems it should be but the misfire is still there. i didnt drive it anywhere just started it in the driveway for about 30 sec.

 

okay..a catalyst damaging misfire is a constant flash.. you cant mistake it.. if it just came on for a minute and then went off and came on again.. then not so bad but i still would not recommend running it with a misfire... pull your coils off.. check the plugs.. get all the moisture out.. hopefully its an easy/cheap fix and not a coil or injector.. or worse.. mechanical..

 

and go ahead and take it to advance auto or autozone, retrieve the codes and relay them here.. that way we can know whats going on and point you in a proper course of action to resolve issues.

 

The check engine light flashing under acceleration is a misfire.