Code 26- New Sub Harness Install

[Clay010]

Morning All,

I recently bought an ST from marketplace and by the time I rode it the next day the code jumped up on my dash. Since then I have ordered a new knock sensor sub harness and installed it. Taking off the old one, the ride connectoin to the knock sensor was so brittle that it basically disintegrated in my hand. Rewired everything and put all the plastics back on and yet..... The code remains.

I really do not want to start stripping down the bike again, especially since its my main mode of transportation. Was hoping someone could tell me a step I missed or point me in the right direction. Thank you!

 

[Mellow]

Typically, but not always, it means the ECU is damaged and the only way to clear the code is to get a new ECU.

I personally believe, but there's no proof, that heat degrades the wires and shorts out the ECU. Some have replaced O2 sensors and fixed the issue but that is a rare successful solution.

Many just ride with the code and ignore it as it shouldn't hurt anything, or it has yet to be proven if it does.

 

[Andrew Shadow]

If the problem is a defective ECM most commonly the code sets after maintaining engine speeds in the vicinity of 4,000 RPM or higher for around 30 seconds or more continuously. There are a couple of simple tests that can be done to gather some data.

Test # 1:
Go through the code clearing procedure regardless of whether the FI light is on or not.
With a fully warmed up engine ride for several minutes while continuously maintaining a sustained RPM close to but not exceeding 4,000 RPM. I would not exceed 3,800 RPM just to allow a little bit of a buffer.
Note whether any codes set and what they are.

Test # 2:
Go through the code clearing procedure again, even if the FI light did not illuminate, to ensure that there are no false test results.
With a fully warmed up engine ride for several minutes while this time maintaining a sustained engine speed of 4,000 RPM or higher for several minutes continuously. I suggest maintaining a minimum of 4,200 RPM to allow a bit of a buffer. The RPM must be maintained above this threshold continuously for a minimum amount of time before the ECM sets the code.
Note whether any codes set and what they are.

Test # 3:
This is not quite as easy to accomplish as the first two tests.
Swap the knock sensors from side-to-side.
Perform test # 1 and test # 2 again
Note whether any codes set and what they are.

If code 26 set in test # 1 there is a chance that the problem is somewhere other than the ECM. The diagnostic procedure will need to be followed to try to determine the cause.

If code 26 set in test # 2, and it did not set in test # 1, the likelihood is that the ECM is defective. There is no known ECM repair for this problem that I am aware of.

A couple of notes:
1- People have reported the code 25 and/or 26 setting at different engine RPM's but it is always around the 4,000 RPM mark. This is why I suggested a minimum of 200 RPM as a buffer.
2- The length of time that the engine speed must be sustained above 4,000 RPM before these codes are triggered can also vary. Maintaining the engine speed above 4,000 RPM continuously for several minutes ensures that sufficient time was allowed for the ECM to react.
3- If the code changes from 26 to 25 there is the possibility that there is a knock sensor problem, assuming that all wiring, connectors, etc., are good. If the code does not change, it remains code 26, then the ECM is again suspect.