A persistent check engine light baffles mechanics

DEAR CAR TALK:

I have a 2006 Volvo V70 wagon with 119,000 miles. For the past two years, the check engine light has been on, and the car’s message panel says the engine system needs attention.

I’ve taken the car to three reputable mechanics, including a Volvo dealer, and no one is able to find a problem. The car runs fine, and I’ve been told that as long as it continues to drive well, I shouldn’t sweat it.

What do you think?

CAR TALK:

It’s odd that the car’s computer hasn’t stored a code. Normally, when the check engine light comes on, the computer will store data that will tell him which component reported the problem and what needs to be tested.

The possible good news for you is that usually when the check engine light comes on, it’s not something that’s going to leave you stranded.

Of course, there are plenty of other things on a 10-yearold Volvo that can leave you stranded, so I don’t want to give you a false sense of confidence here. But the components that turn on the check engine light usually are related to the emissions system. It could be a fuel-air ratio sensor, a problem with the vapor recovery system in the fuel tank, or a catalytic converter. The problem also could be the computer itself.

I recommend requesting the dealer swap in another computer for you as a test, and let you drive the car to see if the light goes off.