'05 XC90 V8 fuel filler cap loose-open message

Apparently one of the most common service calls Volvo dealers get is the
"Fuel Filler Cap Loose-Open" message, with the yellow triangle light. I
read in the manual that you can get that error if the gas cap is not tight
after refueling, or if you refuel the vehicle with the engine running.

We are now getting that error, however our fuel filler cap is tight, and we
always tighten it when we fill up. It clicks many times.

I read it somewhere on the internet, that it could take up to a few
days/weeks for the error to actually show up. Therefore people think back
wondering if they may have left it open or something.

How do we avoid this error message, when we are pretty sure we're tightening
the gas cap until it clicks many times?

Will the error cancel itself after a while? Is there a way to make the cap
seal better? There's a gray rubber O-ring seal that goes against the metal
filler pipe. Wondering if just a bit of plumber's grease would lube the
O-ring and make it seal better. Or does the filler cap need replacing?

Thanks for any info.

Mike

 

Of course the computer doesn't know if the fuel cap is loose or not. It
performs checks by monitoring the air pressure inside the fuel tank as
it opens and closes valves in the venting system. If the tank pressure
stays constant, it sets the "fuel cap code" but it could be something
else - like a faulty sensor or broken vent hose.

--
Mike F.
Thornhill (near Toronto), Ont.

Replace tt with t (twice!) and remove parentheses to email me directly.
(But I check the newsgroup more often than this email address.)

 

We've had this happen twice. First time we stopped at a dealer and they
couldn't find anything (cap, etc. was fine)but re-tweeked the computer
(altho apparently there was no computer problem) and that fixed it.

Second time we didn't bother but waited and in about
a day of driving around the light shut off by itself.

Here's my hypothesis FWIW: if when filling the gas tank you continue after
the auto shut off to "top off" to the next even dollar or whatever (which we
are told NOT to do), there is too much back pressure on the sensors and that
sets off the "cap open" sign. After you run the gas down a little the
pressure is relieved and the light shuts off.

I wonder if any Volvo experts out there concur or not.

 

The diagnostics are only run if the tank is between 1/8 and 7/8 full.

--
Mike F.
Thornhill (near Toronto), Ont.

Replace tt with t (twice!) and remove parentheses to email me directly.
(But I check the newsgroup more often than this email address.)