Persistent Check Engine Light--Emmissions
 

My 1999 Volvo S80 repeatedly displays the "check engine" light, often with the message "emissions systems service required." Sometimes this is preceded with a message about the gas cap. Have taken to dealer several times, yet the problem persists. They havereplaced the evaporator valve, canister valve, vacuum hose, MAF sensor and air filter, O shut-off valve… and yet the darn check engine light comes back on and the “emissions system service required” message displays! The codes they have found are: ECM 4338, ECM 4308, ECM 261A … Any ideas?

RE: Persistent Check Engine Light--Emmissions
 

You need to have the evap. system pressurized and inspected really well.

RE: Persistent Check Engine Light--Emmissions
 

Thanks! I checked with the dealer who works on our car and they said that the evap system was the first thing they checked. They said they feel there really is nothing wrong with the car and that the check engine light coming on for no reason has been an issue with 99 S80's. Of course, how are we supposed to know when it comes on because there IS a problem?

RE: Persistent Check Engine Light--Emmissions
 

They need to do their job and fix it.

RE: Persistent Check Engine Light--Emmissions
 

I agree with Tech. It can be a difficult problem to find, but there is a problem, and it can be fixed.

Make sure they have updated the ECM software.

Some shops are using smoke machines that fill the evap. systems with smoke and make it easier to locate a leak.

It takes someone with good diagnostic skills to look at all the data from the computer data and systems tests to be able to spot irregularities that may lead them to the cause of such a dificult problem. Ask for the foreman of the dealer you are dealing with. They need to use the recources available to them, regarding technical information, and technician support from Volvo. That's why you go to the dealer and pay top dollar for your repairs!

Good Luck!

B