You need that code. Don't take it to the dealer. Take it someplace like Autozone or Pepboys. Some of them will pull the code for you for free. Do this the next time the CEL shows up. Waiting till after the light goes out is of no use. Post the code up here and we'll tell you what it is.
Is your car stock?

 

So true. It's been since last November and no update. Now, nobody will learn anything that might help with their own situation.

 

Yeah, 2003 S2k (50k miles) totally stock. I've got a 5/75 extended warranty and I want to make sure this is fixed while under warranty.

I didn't realize that the code goes away once the CEL is out. Bummer for me and my wallet!

 

check your coolant level, that can cause an irradic idle. I cant believe you paid honda to look at your car...

 

I've seen erratic idle on some other Honda because of low coolant level. I know it sounds hard to imagine the connection between coolant level and erratic idle but that's why this culprit is often missed. With low coolant level, the fast idle valve is not flooded with hot coolant all the time. The time air pocket surrounds the valve, it thinks that it's cold enough to trigger fast idle, thus the jumping engine speed. If not that, I would say the IAC, especially when ECU logs a CEL. It has to be intake air related or bad ECU that drives the IAC valve incorrectly, because no amount of fuel/ignition alone can raise engine speed that high.

 

Last time this happened to one of my customers (idle reving up and down by itself) the IAC was stuck solid. Freed it up with WD40, all is good.

 

Well my S2000 did it again this week. This time I went to autozone and they let me borrow an ODB-II reader. Took about 2 minutes to pull the code. I can't believe that I got robbed of $180 by my honda dealer to do the same thing. I guess I learned my lesson there.

Anyway, I used an Actron CP9135 ODB-II reader and pulled the following code:

P1519

The scrolling text on the bottom read:

"Manf Cntrl Veh. Spd. Idle Speed Control Auxiliary Inputs"

 

^ Idle Air Control Valve Circuit Malfunction.

 

[QUOTE=saucycg,Mar 13 2006, 03:51 PM]I took it to the dealer where they were kind enough to charge me $180 to run diagnostics, which revealed no error codes!

 

to xviper and all the informative peeps here on S2KI. S2KI is one of the reasons I cancelled my extended warrenty within 60 days.