The check engine light just came on today with only 350 mi on the odometer of our new '04 V70 that we bought last week. I'm still on the first tank of gas that the dealer put in. I did notice a squeeky noise coming from one of the fan belt pulleys yesterday.

Off to the dealer service department. What a pain.

Everybody hollers gas cap when the check engine light comes on. Truth is there are hundreds of possible causes for a check engine light. If you know you left the gas cap loose or crossthreaded it, corect the gas cap and pull the ECM fuse for a few minutes. This will turn off the light. If the gas cap is tight, leave it for the dealer.

The dealer ran a full diagnostic. The only thing that came up was the gas cap trouble code.

My friend has a BMW X-5. During the first week of ownership, his check engine light came on. The dealer reset it and told him it was a loose gas cap. That happened to him a couple of more times in the next several tankfuls. He told the dealer to fix it, or give him a new car. The dealer kept it for 3 or 4 days. After the BWM factory mechanic worked on it, he discovered a check/bleed valve in the fuel system that had a small leak which triggered the gas cap trouble code. After replacing that valve, the check engine light has not come for 15,000 mi and counting.

My check engine light came on at about 1/8 tankful. He told me to keep an eye on the fuel level to see if it happens again at 1/8 tankful.

My question is, is there such check/bleed valve in the fuel system of the V70 that could possibly trigger the gas cap trouble code ? Thanks.

I had one of these until the dealer injected "smoke" into the system and found a small crack in a gas filler fitting. This is a special tool which not all dealers have.

check gas cap is tight. 350 miles on first tank I would think you are pretty close to empty.

Fill with gas and tighten cap.

The trip computer shows 120 miles range remaining. The gas gauge shows 1/4 tank. I did not fill up the tank yet, but I checked the gas cap and it is tight. I'm going to try it again this afternoon after filling it up as you suggested.

I'm going to look for an OBD-II analyzer that works with my laptop. As least I can find out what the trouble-code is before bring to the dealer.

Thanks.

After filling up with Unical 91 and making sure the gas cap "clicked", the check engine light is still on. I guess the gas cap was not the problem.

Even if gas cap was loose and you turned it until it clicked several times, or you filled the tank, it may take a week or so for the check engine like to clear. It's not an instant thing. As for OBD computers, may be $$$$, plus unless you are VERY mechanically inclined and engineering-savy, there isn't a lot worth taking apart when it comes to electronics and computers on the new Volvos, especially on such a new car. Hate to say it, but recommend getting your dealer to check it out if the fault doesn't clear in a few days to a week after the fillup.

Thanks for the info. My wife just brought it into the dealer this afternoon. We'll see what they have to say.

I just ordered the OBD-II diagnostic tool/software from digimoto.com for $110. I'm pretty familiar w/ electronics & mechanical stuff. If it's really the case that it take a few days for the check engine light to clear after a loose gas cap, then I can really use the tool. It's good to know the problem before bringing it into the dealer. If it's minor like a loose gas cap, I'll just reset the check engine light myself, and save the hassle of a trip to the dealer.

Thx.

YIKES!