steady/flashing check engine light on my S500
 

I was driving home from wallyworld a few minutes ago when the check engine light went on. I stopped, looked under the hood....nothing amiss. Shut off the engine, disconnected the battery, reconnected the battery, started the engine.....now the light is on continuously.......drove slowly home.....light goes back to flashing after a couple of miles.......I can't find anything that tells me what it means/why it would change......help please

You need to have someone read the codes, why on earth do you think that anyone can diagnose this over the internet.

Your kid just woke you up and said, "I don't feel good." Would you lift his pajama top, look at him and say, "nothing looks amiss" and have him pee and go back to bed, or would you ask a few questions?

The CEL has just told you something is wrong. You can either guess about it and spend lots of time and money raising your frustration level, or you can ask it questions by plugging in a code reader and see what the codes tell you.

FWIW, a flashing CEL is bad, it typically means a serious misfire is occurring, and after that the car should run really poorly as the ECU will shut down one or more cylinders (they will reset on the next engine stop/start cycle).

If you don't want to buy a basic code reader, then get to an autozone (if you're not in California) and have them read the codes (for free). Write down the actual alphanumeric codes, don't just take their summary or translation (or worse, diagnosis). Then post them here and we'll try to help you out.

There is really no alternative for reading codes, unless you just want to start replacing things. ;)

Good luck.

What'd you buy at Wallyworld?

And yes, it is a relevant question!

You're hoping for "gas," aren't you? :D

Well, I don't know about hoping. I don't have a horse in this race, so I'm rather neutral as to whether he purchased gasoline as opposed to Pop Tarts.

That said, if he did purchase gasoline we could tell him to tighten the gas cap all the way and drive the car for a few start/stop cycles; the CEL should then go out.

guess i didnt word the question carefully enough.......i was asking for the difference between solid and flashing idiot light, not an expectation of diagnosis of unnamed fault codes

I found the YEAR and MODEL under your profile; 1996 S500.

Just a WAG but it's probably plugged EGR passages in the engine . . . a real PITA! But read the codes and let us know what shows up.