Driving my new (75000k) car home the check engine light came on. I pulled over and read the owner's manual, tightened the gas cap, and drove on home. AutoZone found the following codes: PO455 EVAP Emission Control System Leak (Large), PO645 A/C Clutch Relay Control Circuit, P1081 Manf Cntrl Fuel & Air Metering, Auxiliary Emission Controls. They cleared the codes, but what do I do now? Where should I look to find what caused them? What is the best resource? (I use a Bentley Manual for my 535i.) Could a loose gas cap cause the P0455 code? When I picked up the car, the AC wouldn't cycle on because it was low on freon. Could this cause the P0645 code? What should I do to check out the P1081 code. Thanks for any help for a newbie.

I have a 99 s70 with 118000KM since 2 years now.
I learned not to worry about the check engine light coming on during summer. It is hapenning to me 3 or 4 times per summer. It is always the same error code. EVAP code. Sometimes small sometime large. For me it is always hapenning when the car sits in the sun and when it is very humid outside.
No it is not the fuel cap like we always see on this board or the owners manual.
I found the best solution is to disconnect the battery for couple of minutes. This is resetting the computer and the light disapear. I figure that if I really have a problem the light will come on again.

The AC problem and P045 codes are not related they just happen on those car at around 80 000KM. All 98-99-00 SV70 will eventually have leaking AC evaporator like you do. Your next problem will be your ETS light coming on sometimes. Eventually you will need to replace your ETS module. Your blower AC fan may failed shortly also.

My light goes on whenever I need to add a little water to the radiator. In other words, the light can indicate a lot of things, and the codes may or may not be relevant to the problem. Check all the easy things first.

I have a '99 V70 wtih 109 KM's and had the CEL light come on. The dealer read the problem as a faulty cannister shut-off value which meant $300+ in repairs. The light was reset and did not come on again. I then had the car tested for emmissions (mandatory in Ontario for license renewal) and it passed with flying colours. There's eleven months left on the lease, so I'm leaving it. It would appear that some problems correct themselves or, just aren't bad enough to fix right away.

a/c system problems won't turn CEL on, but will send error codes to the ECU that can be read with the VOLVO scan tool only. Usually if the led lights on the AC switch flicker at star up that means there are codes stored.

A loose gas cap will turn the CEL on. It requires several driving cycles before the light goes off, after the problem has been corrected. DO NOT fill gas tank with engine on.

Get yourself an OBD II code reader, it's a great investment that will help you diagnose and fix problems on your volvo.
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'88 240, '92 745, '98 v70 John, Tampa Bay