2003 S40 - CEL with no codes?
 

The check engine light on my wife's 2003 S40 came on sometime this past week. I just took it to Autozone to have the codes read and they came up with nothing - no codes. Are there codes specific to Volvo that Autozone's scanner cannot pick up, has the fault cleared but the ECU hasn't cycled enough to clear the CEL, or is something else going on here? I just replaced the gas tank and fuel lines in my Sportage and the PCV system in my 850 R, so I'm beginning to think her S40 was just jealous of the attention. Any ideas?

Not all generic scanners will read the codes.

Sounds like a trip to the dealer or my local Volvo shop then. Thanks Tech.

autozone only reads codes for the top of the engine, if it's a more complex issue or litterally deeper somewhere within the system, the code won't read on their scanner.

Resolution (sort of): Took it to the dealer today. The diagnosics said it was the CVVT gear and solenoid. We actually went through this same thing a year and a half ago not too long after we bought it. We had the local Indie Volvo shop replace these items. It did not register as a permanent fault this time, so the dealership was able to clear the code for me. Hoping the code doesn't pop back up, or that at least I can get it emissions checked and re-registered before it does. Anybody else have this issue?

Does the residue in the oil cap look crusty like hard sludge?
If so the motor might have sludge in there causing the fault.

There is slight build-up on the cap, but I don't think it's recent. We've had the oil changed pretty regularly and the dealership checked it today and thought it looked to be in good shape. Perhaps I need to throw some seafoam or something similar into the crankcase oil?

That might work I really don't like stuff like that in the oil but it might do the trick.
Sometimes people also add 1 quart of ATF and 5 quarts of oil and the ATF helps clean some.

Thanks.. I'll have to think about it I guess.

You can try it. Me myself I do not like it but that does not mean it will not work and work fine.