Ok, my CEL is on. Never before...

Cause unknown. 98 S70 base sedan runs smooth. Nothing irregular that I can tell.
My thought is it is a result of doing a basic tuneup. Car has 110k on it.

I purchased the S70 n/a tuneup package from FCP, and today I changed out plugs, wires, cap, rotor, filters... I pulled the diagram (DIY) from volvoforums to do it as a guide—followed to a "T". No vacuum hoses or wires knocked loose/broken during changeout—it was straightforward and simple to follow. I did disconnect the battery before changing out the hardware though as a precaution.

The only thing I can think of is, before re-attaching the airbox after the wire/plug/cap/rotor changeouts, I reconnected the battery and I turned over the engine to 2x check for misfire or mismatched sparkplug wires...odd sounds...

None at all.

I'm thinking it just needs a reset. If so, how do I do this? And do I need to get a OBD code reader as well?

I read in these forums any autoparts store can do it for free (the reset on the CEL). Am I correct in this?

Well, I would appreciate any advice that any of you have to give.

BTW, the vehicle runs even better than before-smooth idle, great pickup...even shifting...no stutter...no shake and I don't abuse it. Maybe the engine has co—dependency issues ??

Let me know—thanks.

 

Auto parts places will usually read the code but only 1/2 will reset it, unless you can let them know that you recently changed parts or something. Don't tell them that it just came on, just ask them to tell you what the code is.

Double check the little vacuum line that connects to the bottom of the MAF tube. Not sure if that will pop a CEL but it might. Also, if you cranked the car with the MAF disconnected, that WILL do it.

Post back with the code.

 

+1.

Mine came on yesterday, went to autozone, got a scan, got the code.

 

I will be going to Autozone on Friday—will let everyone know what the code is if any...

And yes, when I turned over the engine- the airbox and maf were both disconnected...

Anyway- have a great day and I'll get back to you.

B

 

Well, I'll put my money on the MAF being disconnected as being your CEL. Your probably fine. The thing about the CEL's, they usually do NOT reset themselves. They alert you that something has happened, gone wrong, and will not reset and hide the problem. That can be usefull in letting you know that somthing is going bad.

 

CEL will definately come on if it's running while the MAF sensor is disconnected as it had just happened to me last week, was tracing some slight misfires and had it disconnected to test if it runs better without sensor, light came on, initially thought it will go out after few starts, but no... after about 1 week the CEL finally went out by itself, as my code reader still haven't arrived! It seems the car have ran even better since the light went out...

so I'd recommend getting it reset ASAP as it seems that it will run sort of in a safe mode while the light is on...

 

My CEL came on as well about 3 weeks ago. Ran to AutoZone, they gave me the scanner (held drivers license as collateral for it's return) I ran the code and got a O2 Sensor code. 150$ for a Bosch exact fit.

I reset the code myself since I had the scanner (usually they won't unless you fix something because you'll reset a light and sell it to someone - passing the proplem on) CEL came back on about 3 days later. So I guess I really do need to get one...

Anyone see any good deals on O2 sensors lately? I'd like to stick with Bosch.

 

It's best to get the oem sensors. I usually get them from the yard for $25.