I have a Honda Hornet (CB600F) PC41 from 2007. It's the first model with EFI.

The bike has an error that we can detect by observing the blinking pattern of the FI light: 2 long and 9 short flashes. This gives us:

Diagnostic Trouble Code 29-1.

  • Description:
    • IACV circuit malfunction:
      • Loose or poor contact of the IACV connector
      • IACV or its circuit malfunction
  • Symptoms:
    • Engine stalls, hard to start, rough idling

The symptoms my bike has are exactly the ones indicated above. We have already checked the IACV circuit and replaced the IACV itself but the problem persists. The next thing we're going to do is replace the ECU with the one from a friend's crashed Hornet and check if it's actually the ECU that is faulty.

Has anyone experienced a similar issue and found out what the actual problem is? Any other suggestions? Thanks!

(I don't understand anything about mechanics but I'll forward this to my mechanic.)

  • Can you edit your question and add in the number of times your light blinks. Long flashes and short flashes? Also, please indicate which light is flashing. Is it the ABS light? Thanks and welcome to the site! Cheers. Jul 21 '16 at 0:50
  • Thank you for your input, @DucatiKiller. I've edited my question as suggested. Also, my bike doesn't have ABS. Jul 21 '16 at 9:56
  • I cannot find a reference to a trouble code 29-1 in the OEM Honda shop manual. Are you sure you counted the long and short dashes properly? Jul 22 '16 at 7:05
  • Yes, I'm quiet sure we counted right. I can see the code in the "Shop Manual" for the CB600F/FA(7). I copy pasted the DTC description in my question from the manual itself. If you google "Loose or poor contact of the IACV connector cb600f" you'll find the manual for the cb600s where this code is described as well. It's not the same manual but the DTC are mostly the same. Jul 22 '16 at 10:52

Just to give this question some closure, the problem was in fact a defective ECU. I bought another, used ECU on eBay (with two keys -- so it wasn't from a stolen bike, I hope), and the bike has been working fine ever since.

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