How to diagnose and fix efi issues


Senior Member
Apr 28, 2011
19 ktm 300tpi 6 days / 15 Yamaha YZ250F / 08 Husky 450SMR / 13 ER6N / 13 KTM 300XCW(sold)
Yesterday a friend's bike had an issue, the FI light would stay on and the it would run, but after one minute no more power.

Him and me had no experience with efi so I did a bit of reading and it happens to be very simple.

The way to diagnose a FI error is to first to pull the error codes. For this connect 2 pins together (see service manual) and turn the key on. The FI light will blink in sequence. On my friend's bike the sequence was . .... . .... which is code 14. Back to the owner's manual, code 14 means problem with the TPS (throttle position sensor).

Reading the service manual it explains where to plug your multimeter and what the voltage should be. Example from my friend's bike service manual:


It shows you the sensor output voltage. We saw that the voltage was out of range and adjusted it turning the screw shown in the top picture.

After that started the bike and it ran fine.



Senior Member
Oct 19, 2011
VFR 800 PCX 150
Easy fix if you know which way to go.

Just found out about EFI codes and the like the last couple of days.


Senior Member
Jan 13, 2011
EFI problems are caused by , low voltages from battery , TPS out of sync , bad connectors , dirt or sticky deposits in injectors from gasohol , poor sensors as well such as temp, pressure or O2 , its rare to have a dud EFI unit ,

other faults that mimic poor running are clogged air filters and fuel filters , tthe latter makes bikes run really lean and crappy .

finding the codes usually helps diagnose , but visual checks are also worthwhile

And yes TPS adjustment are VERY VERY sensitive needs a lot of patience and fine adjustment


Senior Member
Apr 27, 2011
Big and Tall put me onto a Suzuki pigtail connector that makes it easy to connect the meter for testing the TPS.
Fits my KTM500.

ADVrider - View Single Post - 2012 ktm 500 exc?

Mine was .590v (recommended .601v) and running ok.
I adjusted it to ~.601v. Couldn't tell any difference other than having to reduce the idle speed by one click on the round knob.
Worth doing for peace of mind though, and handy connector to have for any future problems
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