I've been chasing down a code 25 for a little while on my 2004 ST, my left knock sensor connector looks pristine and I have only 0.2 ohms resistance on the wires from sensor to the ECM.so I would say that part of it is good. My question for those who have dealt with this in the past and had to change out the ECM to fix it is did this fix last or is this going to happen again? It malfunctioned at around 53k miles,if the fix is good for another 53k I can live with that,but at like 800 dollars for a new computer I don't want to cook them like McDonalds cooks burgers,I can ride at less than 75mph for the rest of my life to avoid the FI light, but as an ST owner you know how much fun that is,so if you have some experience with this please let me know,and thanks in advance.
Was the ECM the permanent fix for the knock sensor bug?
- Thread starter nckingz1300
- Start date
Blrfl
Natural Rider Enhancement
There have been ECM failures, but replacing it should be the last resort after you've looked into these things:
Make sure you're looking at the correct knock sensor. There were some failures in early bikes where the bike was throwing the code for the left sensor but the problem was on the right side. This was traced to the documentation not matching reality. (There are a few other errors in the service manual.)
Some early 1300s had the wiring on the right side routed incorrectly and resulted in damage to the wiring, the connector or both. If that's the case, you can either patch the wiring or replace the whole subharness, which isn't particularly difficult or expensive.
I don't recall there being many failures of the sensors themselves, but you can swap the two you have and see if the problem changes sides.
If you've ruled all of that and the rest of the wiring out, then go for the ECM. Before you buy one, see if you can find someone who'd be willing to do an ECM swap. The part changed in 2008, so it would need to be a 2007 or earlier bike.
--Mark
Make sure you're looking at the correct knock sensor. There were some failures in early bikes where the bike was throwing the code for the left sensor but the problem was on the right side. This was traced to the documentation not matching reality. (There are a few other errors in the service manual.)
Some early 1300s had the wiring on the right side routed incorrectly and resulted in damage to the wiring, the connector or both. If that's the case, you can either patch the wiring or replace the whole subharness, which isn't particularly difficult or expensive.
I don't recall there being many failures of the sensors themselves, but you can swap the two you have and see if the problem changes sides.
If you've ruled all of that and the rest of the wiring out, then go for the ECM. Before you buy one, see if you can find someone who'd be willing to do an ECM swap. The part changed in 2008, so it would need to be a 2007 or earlier bike.
--Mark
Thanks,I have had both sides apart and my connectors look good on the right and the left,continuity all the way to the ECM, no continuity to ground,I even put a brand new knock sensor into the mix with no change. I sure would like to prove this with a borrowed ECM but not sure anyone is near me with a loaner and the willingness to do so. I will not shell out the big bucks though until I hear from some of the folks who have replaced theirs and see that the new part keeps it fixed.
Well, I couldn't stand it any more, I ordered a new ECM from partzilla,it cost me $691 but as yet I can not make it light the FI light. I will put up many miles this summer and keep at this thread for any others who may have to deal with this. It kinda seems like a new bike when you get your ST back in order, now I'm excited to get back out there.
Blrfl
Natural Rider Enhancement
The ECM and wiring harness were changed in 2008 and, as far as I can tell, the new ones are incompatible with the older ones.
--Mark
I only know that the part # was the one called for on my 2004,not sure about interchangeability with newer models. I do know that U.K. models will have some differences due to HISS anti theft wizardry. Yes you were correct the new ECM was the needed fix for my knock sensor code,quite a relief when you throw that much money at it for sure,but I did the testing in advance and was pretty sure that was the only part of the puzzle left.
I'm in the same boat with my 2004. I had it in the shop and they swapped knock sensors and the code didn't move. All wires were tested and fine. They said the next thing to do was an ECM but not to really worry about it because it's not interfering with the way the bike is running. It's just a stupid code that will happen above 70mph or if I hit it hard while taking off. For a 2004 with 85,000 miles to not worry about it. Just bring it in every once and a while to read the codes to make sure that there isn't anything else throwing a bad code.
I'm like yourself, I can't stand riding with a red light on. If these darn things were cheaper I'd buy one. But 700 is not worth it.. It would be cheaper for me to put a piece of black tape over the light or snip the wires.
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As long as the computer is reading the anti-knock sensors and the engine isn't predetonating. That is what happened to my brand new '08 BMW R1200RT - ruined the engine in under 6K miles ! ( started piston slapping along with the original knocking of predetonation )
Blrfl
Natural Rider Enhancement
It's a screaming bargain right up to the point where you get the repair bill for piston, valve and cylinder head damage caused by predetonation.
You only get the code at high speeds because that's when the engine makes enough noise for the ECM to notice that it's deaf in one ear. You tend to get knocking at any speed where you're on the throttle, and if the ECM can't hear it, it can't adjust for it. I don't have data to back this up, but not hearing knocking may make it think it's okay to advance the timing enough to make it worse.
Take TourNut's advice and fix it. If the price tag for a new ECM is too high, find a used one.
By the way, your mechanic is a nimrod.
--Mark
Andrew Shadow
Site Supporter
That is what it will do within the limits allowed by the programming or until it does hear the knock.
Do you have a cruise control installed?
I was wondering that too Dan. But then he said it slso happens under hard acceleration so I did not respond. But maybe his idea of hard acceleration is keeping the RPM's wrapped up there and shifting high.
Time for update as I said I would from time to time. I have a couple thousand miles on it with the new ECM, and have not had the issue with knock sensor fault, I don't mind the $691 for the peace of mind I have now,the code popping up before was chiseling at my enjoyment of an otherwise excellent bike. Since then I have added a sargent seat, backrest, and a set of Pirellis and the bike is better than ever.
Hi, regarding this (F1 light up an indicated for knock sensor failure), we can buy a new ECM but the problem is some ST used HISS that mean we have to reset the ignition key to use together with new ECM.
Blrfl
Natural Rider Enhancement
If the failure is actually in the ECM, there's not a whole lot that can be done about it. HISS or not, replacing the ECM should be the last step, but even if you borrow one for testing, the borrowed unit should have a key that will make it run the engine.
Outside of the ECM are the wiring and the sensors themselves, both of which are testable.
--Mark
But mine 04 ST gave F1 light indicator for knock sensor, we try to replace both left n right but the result is same. So this mean the problem is not with the sensor. Of-course ECM is an expensive but what to do. One thing U can do is place a black tape over the lamp.
Ok after both knock sensors already changed with the new one and still code 25 or 26 come out, it must not the failure of ECU, maybe something goes unusual in the engine since the sensor sending the warning. The name `knock sensor' itself mean sensor for any unusual vibration in the engine.
Blrfl
Natural Rider Enhancement
The knock sensors listen for fuel detonating before it should. The fault means the ECM, is not hearing anything from the knock sensors under conditions when it should.
It seems you're making an effort not to replace the ECM because it's expensive, but that's usually where the fault is if the wiring and connectors down by the sensors are undamaged. The sensors themselves don't have a lot to go wrong.
--Mark
Blrfl
Natural Rider Enhancement
Swap the ECM.
--Mark
--Mark