I am having this wierd issue on my 2013 Ktm Duke 390. This happened 3 times in the last month, never before. On the lower gears usually at 6-7k rpm the bike makes an instant engine break-as if the engine stopped; it lasts less than a second actually, and the yellow engine light at the dash gets on and off in that second, and it just continues to work normally.

This all happens in a blink of an eye, and very harsh, on the last time it hurt my wrists.

It never happened at high speeds, but I'm not feeling safe about that. The service couldn't find anything odd(though I don't trust them much).

I've filled the tank few times, but it happened again. So I don't think it's caused by a dirty fuel or something like that.

Do you guys have any idea what might be the cause of it?

  • Which light is coming on? The owners manual suggests the MIL light (engine icon) is red, and the general warning (triangle with !) is yellow.
    – raydowe
    Commented Mar 30, 2017 at 11:05
  • it's the light with engine icon. But not red, they are the same color with the warning light. Commented Mar 30, 2017 at 11:15
  • It seems the 390 ecu is smart enough to store error codes. Did your workshop check to see if it had logged anything? It looks like it uses odb2 so you can probably get a generic tool to check it. Like this: youtu.be/1uXYin5hL94 Commented Apr 3, 2017 at 7:51

2 Answers 2


I am guessing some sensor in the bike is telling the engine to stop and showing the yellow light.

Have you ever tilted the bike a good angle to the left or right? the lean angle sensor may be giving a problem.

Try asking the mechanics to disable that sensor and ride the bike and see if the engine stalls or light comes up.

Also check the temperature sensors, Bikes with ECU get data from various sensors and sometimes shut the engine for safety reasons which sometimes is a pain.

  • I don't think it is the lean angle sensor, but temperature might be the case. And since you reminded me of sensors, the side foot sensor might be the responsible too. I'll check it out. Thanks. Commented Mar 30, 2017 at 9:09

If you're already mistrusting of the service department you're using, I'd definitely get somewhere that you do trust.

For something like this, especially on a specialized bike, I'd go to a reputable dealer-based service bay.

I had a relatively similar issue on my Monster 821 while it was still fairly new. The bike would, under non-repeatable (read: picky) conditions, violently throw itself into limp mode, and show up on the display. Rather than the rapid slow-down you're experiencing, this was more like a stall - but a similarly startling (and dangerous) thing to have happen at speed.

Local dealer couldn't find any issue, but after it happened a second and third time I got a little more forceful, and a different tech took a look. Turns out it wasn't throwing any new codes for them to find, but there was a throttle-sensor code stuck in memory from back at the manufacturer, and once they flashed the ECU to get rid of it, it was totally fine.

While that doesn't specifically answer the issue you're having, it could be something similar that's stuck deep in the ECU's memory - I'd inquire with the dealer about the possibility of something like that, or if flashing the ECU back might help (also check to see if there might be an ECU update you're missing).

Let us know what you find, and safe riding.

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