I have a 98 accord v6 that will jump idle between 1k and 2.2k rpm. When driving this is not too much of an issue until the transmission down shifts then the engine tries to catch up. Getting multiple cylinder misfires and air idle control.

The codes I am getting are:

505 code and cylinder misfire code, I don't have the number. I did reset the codes and now only the 505 code comes up at the moment.

It was running fine the other day and then just today this happened.

  • Which exact codes are you getting? If you clear the codes, do they come back? What have you tried to do to fix it? I suggest you start by cleaning your MAF (if it has one). If it doesn't, then do an upper intake cleaning and see if it helps. Also, try taking the IAC apart and cleaning it. Jun 18, 2015 at 1:05
  • Smells like a vacuum leak if you ask me. How are your fuel trims?
    – Zaid
    Jun 19, 2015 at 2:51

1 Answer 1


P0505 appears to relate to the Idle Stabilization Value or Air Idle Valve. I'd suggest checking the wiring is intact and firmly plugged in first followed by a thorough clean of the valve and throttle flap with a suitable solvent. If this doesn't work it may be a case of looking for a replacement valve I'm afraid.

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