Low Engine Performance Light

I have a 2003 Volvo XC70 with 87K miles on it. I have kept it serviced. For the last few years I have had an intermittent problem with the engine light coming on saying I am having engine performance problems, that I can (sometimes) alleviate by tightening the gas cap. I make a point of tightening the cap til it clicks when I fill up, so I don’t know why this happens. Also, sometimes it happens and I can feel the engine slowing down. It tends to happen more on very hot days when it has been sitting outside of my office building in the sun all day (there is no shade to park). I have a 10 minute ride home and by the time I am 5 minutes into the drive the light comes on. When I get home I pop the fuel lid and tighten the gas cap (even though it feels plenty tight) and by the next morning the light is often off . My dealer has no idea what is going on, but there is something wrong. Any help out there?

First, you need to have the malfunction codes read. Go to an auto parts chain store and ask them to read the codes, which they will do for free. Then write the codes down in “P0123” format and post them here.

If by chance the code is P0455, the problem may be a purge valve in the gas vapor recovery system sticking open. These have a tendency to stick open in hot weather and would cause the check engine light to come on. Also, there are several hoses that tend to crack and cause vapor leaks which will also set the P0455 code.

+1 to jesmed’s advice.

Additionally, when the OP is at that auto parts store, he might want to consider buying a replacement gas cap. The gasket on the cap can deteriorate over time, and–whether it is really the root of the problem or not–it is not unreasonable to believe that the cap is ready to be replaced.

Just be sure to buy a cap that is specific to your make, model, and model year.

They replaced the purge valve and the gas cap a while back. It is at the dealer now – it died on me a couple days ago after I posted initially, and they are working on it again, trying to figure it out…

If purge valve and gas cap have been replaced, next suspect is cracked hoses. There are several hose fittings on these Volvos that tend to crack. Have the system smoke tested. The smoke will pinpoint the leaks.