Resetting ECU Settings On Hyosung

First of all, you must understand what is ECU in general on both motorcycles and cars are for and think about it again if you really need to do this on your bike?

The Engine Control Unit (ECU) learns” about your engine as you ride or drive your machine. “learning” is actually a process that the ECU uses to track the tolerance changes of the sensors and actuators on the engine.

*This is just a sample picture of ECU that I found online.

However, Hyosung’s stock ECU neither stores codes after the ignition key is turned off nor does it have a memory for storing any mythical learning.

It has a pre-programed set of parameters and based on the sensor inputs adjusts the fuel injector opening times accordingly. It will NOT learn anything but the base map settings can be reset if it’s necessary.

Myth & Reality?

The Myth

There is quite a bit of mythology revolving around resetting the ECU. Many people mistakenly believe that they need to reset the ECU after installing major engine modifications or parts such as exhaust pipe. Others believe resetting will resolve engine problems. Neither are correct. (Yes, resetting ECU may help in solving engine/electronic problems but the diagnosed errors has to be fixed first)

The Reality

The ECU is always tracking the engine’s sensors and actuators when the ignition is switched ON. Resetting the ECU does not cause the ECU to learn engine changes any faster. The ECU is always  tracking the gradual changes in the engine sensors and actuators. The ECU never gets satisfied with a setting, and is always updating the trim values. It will discover whatever change you made to your engine and make the appropriate changes when you’re riding.

There are only two reasons why you would want to reset your ECU. One is to clear a CHECK ENGINE error code after fixing the problem that caused the error.

The other is to reset the spark advance trim value. The advance trim controls how much the timing is retarded from what the factory engineers considered optimum. I’m not sure if this applies to a Hyosung machine but it was shared over a coffee session from my friend.


I reset the ECU, and now the bike runs rough! Why? The engine may run rough or idle poorly right after ECU reset. The ECU now has default numbers in its base settings – it has to adjust them to match the tune of your engine and its sensors and actuators. You will need to ride your machine for quite sometime before the engine will settle down again.

How To Reset?

If you want to reset the ECU settings on your Hyosung/Blade/Comet for whatever reason you think it’s good, please see the steps below:

Disclaimer:  Do it at your own risk. I am not responsible for any damage caused by this action.

1. Turn OFF the engine, and unplugged the ECU from your bike. (Also ensure to turn “OFF” the ignition switch, or electronic parts may get damaged).

2. Remove the -ve and +ve wires from the battery terminal respectively and leave it for 10-15  minutes (some says only -ve would do ) Well, you decide?

Note: I can’t stress enough, removing any battery terminal of a running engine is strictly prohibited. The moment such removal is made, damaging counter electromotive force will be applied to the ECU which may result in serious damage. On another note, never connect an ohmmeter to the ECU with its coupler connected. If attempted, damage to ECU or sensors may result.

3. Plug the ECU back to your bike,  reconnect the wires to the battery terminal. It is also advisable to measure voltage using a voltmeter at each terminal. check to make sure that battery voltage is 11 V or higher. Terminal voltage check at low battery voltage will lead to erroneous diagnosis.

Note: Battery connection in reverse polarity is strictly prohibited. Such a wrong connection will damage the components of the FI system instantly when reverse power is applied.

4. Turn ON your engine  and leave it running idle for 15 minutes (Do not rev the throttle)

3. Once you’re done with the 15 minutes idle running, turn OFF the engine and leave it for another 10 minutes.

4.Finally, turn back the engine ON,  ride your bike in a traffic for a day or two (If you plan to ride in traffic often) or Rev your bike on a highway in high RPM whenever you switch gears (If you plan to ride on long distance often)  and eventually your bike will accustomed to the way you ride.


In my personal opinion, I’ll never reset the ECU settings unless I have issues with the engine. i.e. There is an error(s) code detected etc.

i.e. I been riding my bike below 100KM/h when I initially got my bike and when I rev it at higher RPM to go faster (150KM/H), it seems to be struggling. However, when I rider it for a about 1 hour, it seems to be fine. This is because the ECU has relearned / accustomed to my riding style without even resetting the ECU settings. So do you think still that you want to reset your ECU settings? think again 🙂

If you have any questions, drop them at the comment box below and feel free to share this article via the social buttons.

Inline Feedbacks
View all comments

Hi Chris
I have a HYOSUNG GV125-S EURO 5, can tell me how to turn off the Check Engine Light on the dash. I reset the ECU and the only problem I have left is that the engine light turns on continuously when I turn on the ignition but when I start the engine it turns off. I couldn’t find anything on the internet that explains how and I couldn’t even find the

Muhamad bin juhari

Sir. My motor parking for 5year. After change new batry its still cant start.


hi, do you own gv650? mine giving bad idle u know how to tune it back?


Hi I recently bought a new scooter from china it’s a wangye 125. It has an efi. I ran it in at around 20 /25mph as instructed in the book for first 100 miles but now When I hit around 35 it can get sluggish and warning light flashes. I checked online for info but not much on this bike. I took spark plug out and it was black around the top so I assumed it was the fuel that was too rich so I tried to adjust air intake valve which has helped a bit but still can get… Read more »


My hyosung gt250 efi. One cylinder (rear) not firing bt injectors are spraying….
Sometimes injector not spraying enough fuel
Sometimes not enough spark
It’s behaving wierd
1. Ignition coils fine
2.Spark plugs fine(sparking)


What if the caps are fine ?