Hi guys. Sorry if this has been asked before. There were some similar problems I found in searches but nothing that seemed to fit exactly.

My ~71k mile '08 Fit recently started, on occasion, having some rough idling when the engine is cold. I suspect the problem is with a sensor, though, because it only does this when the blue "cold" warning light doesn't come on. This means to me that the computer doesn't know then that the engine is cold and tries to have it run at "normal" settings rather than warmup settings.

Is my reasoning correct here? What should my next step be either to confirm the problem or fix it?

EDIT: I forgot to add that there is no CEL here.

 

According to the dealer, to whom I took my car to for a similar problem, they can hook up your car to their diagnostic test set which is more comprehensive than an OBDII scanner. It can test the health of all sensors, apparently. It might cost you $100 at most.

Oh, and be prepared for the standard "you need a valve adjustment" response to which they'll ask $400 for. I'd rule out valves by having the adjustment performed, but not necessarily by the dealer. It's a relatively easy job.