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FI Error C40 after about 20 mins

Posted: Sat May 31, 2025 11:27 am
by jeremyp
I’ve searched and searched for this but can’t find anything.
On my K7 400 the FI light comes on after about 2O minutes of riding. It’s an ISC fault.
I’ve got the service manuals and done all the diagnostics and the ISC sensor checks out fine. I’ve even gone through the procedure of resetting the idle speed.
The light resets if the bike it turned off.

It idles and runs fine.

Any ideas?

Thanks in advance.

Re: FI Error C40 after about 20 mins

Posted: Sat May 31, 2025 3:08 pm
by Ministerofsillywalks
Sounds like something for a dealer with the right diagnostics to take a look at. Modern vehicles are beyond amateur diagnosis and some tinkering.

Re: FI Error C40 after about 20 mins

Posted: Sun Jun 01, 2025 10:25 am
by roadster
If the idle speed is actually stable and doesn't change after the light goes on then the control unit must be getting inconsistent feed value from one of the sensors. For example one of the more obvious ones would be not sensing throttle closed position due to sticking mechanism/switch or throttle position sensor. My inclination would be to live with it if the scooter is running OK, but checking and cleaning all the harness connections might be the best start. I did see a thread on Burgman USA that found a bad multi-pin connection between ISC and ECM which fixed this problem. Reassemble connectors with some vaseline or dielectric grease to prevent corrosion.

Realistically an intermittent fault like this is either heat or vibration sensitive and a nightmare to diagnose statically. On a newer vehicle dealers would exchange components but would struggle to get any further with electronic diagnostics alone.

Re: FI Error C40 after about 20 mins

Posted: Mon Jun 09, 2025 9:23 pm
by jeremyp
Thanks roadster. That’s really helpful.

Is it easy to dismantle the connectors (ie pull the pin receptors out of the body to check/clean)?

Re: FI Error C40 after about 20 mins

Posted: Tue Jun 10, 2025 9:41 am
by roadster
jeremyp wrote: Mon Jun 09, 2025 9:23 pm Thanks roadster. That’s really helpful.

Is it easy to dismantle the connectors (ie pull the pin receptors out of the body to check/clean)?
No that's not usually easy without specialized tools and/or extremely good eyesight to see how to depress the tabs which hold the pins in. Pins which appear lower than others in a block could be worth attention but I would settle for a spray of contact cleaner followed by some grease after the contact cleaner has dried. Do not to breath in any fumes from contact cleaner which contains carbon tetrachloride!

Re: FI Error C40 after about 20 mins

Posted: Tue Jun 10, 2025 4:45 pm
by Andym
TPS is the mostly likely suspect. There is a video on YouTube.

Andy