I was driving along like normal and the check engine light went on. I was just thinking if this light goes on every 3 months this could be a real
 nuisance. At 1000 miles it went on and i took it to the dealer to get it cleared and checked out. All they asked was did you tightened the gas
 cap? At the time i was driving down a steep hill, not getting gas.

 Again the light goes on while driving normally. On the one hand i dont want to get it cleared since the car drives fine. On the other hand i wish
 there was a way to find out what the problem is and clear the message without going to the dealer weekly if this occurs alot.

 Does anyone out there know if this thing will clear after a certain number of driving cycles? Also is there a tool to find out what the problem is
 and clear the message for 1999 Volvos?

 Andrew

 S70 GLT 1999

 If the gas cap is not properly tightened when you fill up, the check engine light will trip. I don't know if properly tightening the gas cap will CLEAR
 the light, but it's worth a try. As far as keeping it from going on, if there are no other problems make sure that you turn the gas cap until it kinda
 clicks/falls into place....

 Scott
 --
 '98 S70 T5 5-speed - Tropic Green/Tan - Spoiler, Fog Lights, Sunroof, Climate Control, SC-816 w/ Changer, Leather Wheel, Cold Weather
 Package, Trip Computer

 Hi

 Indeed, the check engine light may go on if you did not tightened your gas cap properly, but it does not happen immediately. It takes a couple of
 days before it lights on. This can also happen if you fill up your tank while the engine is running.
 If your light goes on because your gas cap was not tightened properly, I once read about a trick to shut it off. You drive at 60 mph or more for
 at least 10 miles, then you stop and let the engine idle for at least 1 minute. Then you drive again for 10 miles at the same speed, stop and let
 the engine idle for another minute.
 It should go off immediately or after you stop the engine and start it again (I am not sure). The computer will nevertheless keep the code during
 50 or 60 start up.
 --
 Claude

 Thanks for all who posted answers to this message.

 I originally filled the tank and ran the about 1/2 way down. I was fiddling with the a/c button turning it on and off a fews times as it as i felt i was
 too hot or too cold after running the a/c for awhile...then the check engine light went on.

 I drove the car highway at 65 to 70mph and some mixed city for another 50 miles after the check engine light went on.

 I later got gas and topped the tank out. After using the car for an addition 4-6 trips of cycling on and off the light went off to my surprise.

 I guess i am still learning about this car.

 Andrew

 Andrew, I had a problem with my '98 S70 with the recurring check engine light. First went on at 1500 miles and then kept coming on every
 couple of months. Dealer first told me to check the gas cap, even supplied a new one from the 850 (a bit bulkier and no tether - said these work
 better). Then they replaced just about every part of the fuel evap system including charcoal canister (several times), check valve, purge valve
 (same thing? also several times), even a rollover vale. Nothing doing. Still a check engine light every few months (once within 2 days of the
 "repair"). I finally got really fed up with the inadequate approach the dealer took (replacing same parts over and over again), which didn't look
 beyond the warranty period (or did it? After the warranty expires just looking at the check engine light costs $100, and if there is something to
 replace like a charcoal canister - watch out...). I wrote a letter to the dealer's service manager describing my plight. The manager got personally
 involved. He also got the VCNA rep involved (do not remember his name). Took them over a month (I had a '01 V70 loaner the whole time) and
 finally they ended up replacing the gas tank and some kind of flow restricter (a tiny washer-type part). So far so good since January no check
 engine light. The jury is still out, of course, but it looks good. The Volvo rep told me sometimes the gastanks end up with clogged lines due to
 manufacturing (can you say "poor QA"?) and cause these problems. So, do not ignore the check engine light, it may mean something
 expensive once the warranty expires. Insist on them getting to the root of the problem and don't except getting the same "fix" over and over
 again. The check engine light SHOULD not be coming on at all unless something is wrong with your car. In my state the car will fail the annual
 inspection (as mine did once) of the check engine light is on.

 As to your other question about a tool, I bought an OBD-II reader at the AutoZone made by Actron for about $150. This gadget plugs into your
 OBD-II connector and is supposed to be able to read and clear the Diagnostic Trouble Codes (DTC). Well, it reads SOME of the ones which
 cause Volvo CE light. When I was having my woes, the codes the dealer was pulling were 611 and 612 (fine and gross vapor leak or some
 such thing). The Actron tool was reading 0, which means no codes. However, when following the procedure to clear the codes, the CE light
 would go out (only to come back a few days later, of course). I have checked on the Actron website and it seems they have firmware upgrades
 for this tool. Mine happens to be one of earliest versions out there. So, who knows, maybe the newer version of firmware will read more codes
 the Volvo produces. At $150 it's not a bad tool to have. I already diagnosed and fixed my dad's '96 Chevy Lumina with it and reset his check
 engine light (it didn't come back, so the diagnosis was correct).

 Good luck.
 

 --
 Vladimir. 1998 S70. Base, 5-speed manual.

 Vladimir,

 Thanks for the note. I will watch the CE lights and get it documented by going to the dealer if this situation continues to repeat. Your right about
 the warranty issues in the future.

 Andrew