recently I've had my FI warning light come on, it happens during or just after a blat on the trottle above 5000 revs, when i stop and put the side stand down i a sequence of flashes in this order

2 long which i believe is 10+10=20 then 5 short total 25


fault 25 refers to the knock sensor

I have a couple of questions ..........

am I reading the fault correctly
if so - has anyone ever had a problem with the knock sensor before

I haven't checked aanything yet, I know it could simply be a bad connection but if the sensor is faulty - how much do they cost, is it a unique honda part or do other bikes have same one.


cheers for some advice

read this from another post

http://www.cbr1100xx.org/forums/index.php?...l=PCII+problems

does anyone know where connector 6P WPC is located, the knock sensor seems to feed into this, it might be 5P, hard to make out on the diagram. I also noticed that the wire that runs to the ECU is screened, I assume this is to reduce noise.

OK I have checked the wiring and it is ok, but i still have a problem indicating the knock sensor, symtoms are after riding for maybe about 5 mins on comes the FI warning light, if I drop the sidesatand I get a count of 25, if i switch off and restart the light stays off for another 5 mins or so then on it comes again, is this basically saying my knock sensor is faulty or if I resset the ECU (clear faults) will it just go away, in other words will this fault condition remain until i do a reset or does it keep detecting a fault every time i go through this cycle, second, I cannot find the link to reset the faults in the ECU, 99 XX, I've had the ECU out but didn't see any reset link

The reset connector is a two prong connector on the right hand side. It's near the rear on the cowl.

thanks for taking the time to reply



i read on another forum that it was a white connector - it seems to be black on my bike



apart from that it would seem that not too many people know much about this, i am trying to understand how the fault system works, for e.g. if a fault is recorded will it continue to show even if it was a one off until i reset the ecu, or does the continuous fault reading mean that i have a reoccuring fault, i am hoping it was a one off and once i rest the ecu it will be gone, does anyone really know

The faults are recorded and retained in the ECU until they are cleared and reset. I believe you may be able to reset the ECU by disconnecting the battery for a short time too.

does anyone know if the knock sensor on our xx is the same a a car, i.e. a standard bosch part or similar, I'm working with the idea that I can use saame from a car, I've checked all the wiring and I am still having a problem so I have to assume the sensor is faulty, not easy to get over here in Thailand.

does anyone here really know about the knock sensor, technically what is a failure apart from an open circuit, what is the ecu looking for to determine a fault condition, i had a faultless bird until 25

I have a little more information on this problem.

I went for a longish ride on the bike a couple of days ago and noticed the FI light was staying off and therefore not showing the usual fault 25 (knock sensor) this has been the pattern over the last few weeks - showing errors less and less - unless I really gunned it to high revs and full throttle bursts even then it may not come on, well my chain was in need of adjustment so I tightened it up yesterday and now the FI light has started to come on every time I ride it even without gunning it.


My theory here is that excessive vibration is causing the problem, not just the chain and drive but a combination of many things combined to give an overall excess in mechanical noise which the knock sensor is picking up and flagging an error because the ecu is not getting what it expects, I have noticed recently that the engine is vibrating more I believe added to the drive that may equal excessive noise causing the knock sensor to appear faulty.

I have removed the sensor and added a rubber O-ring which didn't make a difference


So what can I do that may reduce engine vibration, is it possible that the balancer shafts are causing excessive noise/vibration - if so how are these adjusted, is it a shop job or do it yourself, are there any other things on the bird that can cause excessive vibration ?

some help and suggestions would be most welcome about vibration.


PS the chain and sprokets where replaced about 2 months ago.

how did you align your rear wheel? What method I mean, the marks can be off the wire with a zip tie on it got my straight. I was perfect on the notches when I put my new tire on. But it vibrated pretty bad at speed. I bent a coat hanger straight, hammer tapped it on the cement to get it pretty good. Put a 90 degree bend in 2 inches from one end. Put the short bent piece in the the swingarm bolt hole. Adjusted zip to front edge of bolt. Checked the other side and if was off. Once I squared it up to the swingarm, all was smooth again.

Good luck