Article [13] ST1300 - FI Codes (MIL) Malfunction Indicator Lamp

[Mellow]

The PGM-FI MIL denotes the failure codes (the number of blinks from 0 thru 33).

When the indicator lights for 1.3 seconds it is equivalent to 10 blinks.

When more than one failure occurs, the MIL shows the blinks in order of lowest to highest number.



Code Reset:

• Turn the engine stop switch to the RUN position.
• Turn the ignition off.
• Using a jumper, short the brown and green/orange wires on the diagnostic connector.
  
• Turn the ignition on.
• Remove the jumper from the diagnostic connector.
• When the FI indicator lights, immediately short the brown and green/orange wires on the diagnostic connector.
• Verify that the FI indicator goes off and then begins blinking.

 

[ASPC]

 

[eyrepb]

The PGM-FI MIL denotes the failure codes (the number of blinks from 0 thru 33).

When the indicator lights for 1.3 seconds it is equivalent to 10 blinks.

When more than one failure occurs, the MIL shows the blinks in order of lowest to highest number.


Code Reset:

• Turn the engine stop switch to the RUN position.
• Turn the ignition off.
• Using a jumper, short the brown and green/orange wires on the diagnostic connector.
  
• Turn the ignition on.
• Remove the jumper from the diagnostic connector.
• When the FI indicator lights, immediately short the brown and green/orange wires on the diagnostic connector.
• Verify that the FI indicator goes off and then begins blinking.

Just bought an '06. Great info. Thank you! /r Brad

 

[Happy Rob]

Looking for wise man or woman!!!I have dreaded code 26. Did some searching here as I always do with any issues on my 13. Code 26 is right knock sensor or wires melted or broken. Bike runs great. Over 4200 rpm’s and I get code 26. Let me know if I’m going in right direction please
1 remove tupperware
2. Access knock sensor and wires!
Then what?? If wires look good what do I do next??? I see where others replace knock sensor and it don’t fix issue. I u d’état and it can also be ecu unit. I do t want to start buying a bunch of parts only to not get problem fixed

 

[MattSTlouis]

Looking for wise man or woman!!!I have dreaded code 26. Did some searching here as I always do with any issues on my 13. Code 26 is right knock sensor or wires melted or broken. Bike runs great. Over 4200 rpm’s and I get code 26. Let me know if I’m going in right direction please
1 remove tupperware
2. Access knock sensor and wires!
Then what?? If wires look good what do I do next??? I see where others replace knock sensor and it don’t fix issue. I u d’état and it can also be ecu unit. I do t want to start buying a bunch of parts only to not get problem fixed

Some people have gotten lucky and replaced the knock sensor and it worked. You can switch the left and right sensors to see if the code changes to a 25.

On mine I tried a few things and finally just replaced the sub harness for the knock sensors and found another ECU. That fixed it.

Good luck.

 

[Buckeyechris]

Looking for wise man or woman!!!I have dreaded code 26. Did some searching here as I always do with any issues on my 13. Code 26 is right knock sensor or wires melted or broken. Bike runs great. Over 4200 rpm’s and I get code 26. Let me know if I’m going in right direction please
1 remove tupperware
2. Access knock sensor and wires!
Then what?? If wires look good what do I do next??? I see where others replace knock sensor and it don’t fix issue. I u d’état and it can also be ecu unit. I do t want to start buying a bunch of parts only to not get problem fixed

Rob,

I'm very sorry to hear that you have joined the sad fraternity of owners who have experienced a code 25/26. I started receiving error code 25 (left knock sensor) on my '05 ST13 in the Fall of 2023. This type of problem is more prevalent with '03-07 ST's, but '08 and newer do sometimes have this problem.

There are a half-dozen or more reasons why you are receiving the code. If you have a Honda service manual, it contains directions on how to test your wiring from the knock sensor rearward to you PGM-FI (ECM). Because your code is the right knock sensor, you problem could be that the plastic connector of the wire that runs from the sensor to your ECM has become brittle and is no longer allowing the wire to remain connected to the sensor. It is not uncommon for that connector to deteriorate from the heat produced by the nearby headers.

In my case, I followed the procedures in the manual. Unfortunately, the knock sensors and the wiring to the ECM were not the cause. In the end, my ECM was the culprit. I found a new unit from a part supplier in Japan, and had it shipped to me in the US. After replacing it, I have not experienced a FI error code. Last I knew, the ECM for your model year was still being produced by Honda and readily available. However, they are not cheap. Therefore, I recommend that you go through the testing sequence to rule out any wiring problems before you spend a grand or more for a new ECM.

Wishing you the best.

Chris

 

[Andrew Shadow]

Be aware that there is a mistake in the manual regarding which code is left and which is right. I don't know if/when the manual was corrected- i.e. What year manual has the correct information. Search this site and you will find it.

 

[MidLife]

After replacing it, I have not experienced a FI error code.

Did you notice the throttle being less snatchy with the new ECM?

My 03 is tamer since the swap.

 

[Buckeyechris]

Did you notice the throttle being less snatchy with the new ECM?

My 03 is tamer since the swap.

I did not, but I have a G-2 throttle tamer installed Lol.

 

[eyrepb]

Evening folks. Until now I've not needed to use the "Service Connector". Is this it?

 

[eyrepb]

I guess so

youtube vid

 

[Andrew Shadow]

Yes, that's it.

 

[eyrepb]

OK, so 2006 ST1300A; from start, when revving to >5k, Fi lights; Stays on; RPM drops ~500rpm; runs normal; resets on next stop/start. Reads no blinks ("0"?). Where should I look next? (New ECU?). Thank you;.
/r
Brad

 

[Buckeyechris]

Brad,

You will not get any failure codes while the engine is running. When this happens again, shut down the engine, but keep the key in the on position. At that point, the Multifunction Indicator Lamp (i.e., the FI light) will begin to blink. Here is a link to the ECM fault codes: https://stwiki.notonthe.net/twiki/bin/view/ST13/ECMFaultCodes. Slow or long blinks count as 10 blinks. Count the number of slow/long blinks along with the fast blinks, add up the number of blinks to determine your error code. You will likely get a code 25 or 26. The former is the left knock sensor, and the latter is the right knock sensor. Unfortunately, this error code is not usually the result of a failed knock sensor. It's possible that it could be a faulty wire that is not completing the circuit to the ECM. But that wasn't the cause in my situation.

If you have a Honda Service Manual, the knock sensor troubleshooting sequence begins on page 5-46. The color codes for the knock sensor wires in the SM did not match the wires on my 2005 ST. However, once you get to the knock sensor wire connectors, the color of those wires is easy to see visually.

Chris

 

[eyrepb]

Chris, Thank you for your explanation. I will give it another round.
/r
Brad

 

[eyrepb]

20260325;
Read ECU codes;
2 - Loose MAP sensor hose; faulty MAP sensor
9 - Loose or poor IAT sensor contact, wire; faulty IAT sensor
23 - faulty 1/3 O2 Sensor
24- Faulty 2/4 O2 Sensor
25 - loose, faulty (LEFT) knock sensor/connector
Guess I have some inspect R/R to do.

 

[eyrepb]

@Igofar White Courtesy Phone consult: (Thank you Larry for your time and advice!)
Spark plugs tight, ensure no counterfeit!!
inspect coils; including grounds
No exhaust wrap! (PRO; insulates engine from exhaust pipe radiant heat; heat goes out tail pipe. CONS: causes condensation corrosion)
inspect knock sensor sub-harness
Turn off via kill switch, then ignition
3 bars idle down before ride
Replace Battery (2018)
Throttle Body sync. DONE
Check all wiring; especially grounds

I cleaned and dialectic greased coil mounts and low voltage coil connectors
I checked spark plugs, I overlooked during my general overhaul last year.

Manual calls for:
Stock: NGK CR7EH-9
(.031-.035)
Optional: NGK CR8EH-9
8-12k miles interval

Plugs installed by PO NGK CR9EH-9 (cooler for sustained high speed)
12K+ miles

I ordered set of NGK CR7EH-9

Spark Plug wires may be original (70k+ miles; 20 years); some sources say OEMs are inferior to what's now available.

Recommendations/sources welcome for replacement plug wires

UPDATE; I swapped knock sensors. Code 25 stays with harness?

 

[Buckeyechris]

@Igofar White Courtesy Phone consult: (Thank you Larry for your time and advice!)
Spark plugs tight, ensure no counterfeit!!
inspect coils; including grounds
No exhaust wrap! (PRO; insulates engine from exhaust pipe radiant heat; heat goes out tail pipe. CONS: causes condensation corrosion)
inspect knock sensor sub-harness
Turn off via kill switch, then ignition
3 bars idle down before ride
Replace Battery (2018)
Throttle Body sync. DONE
Check all wiring; especially grounds

I cleaned and dialectic greased coil mounts and low voltage coil connectors
I checked spark plugs, I overlooked during my general overhaul last year.

Manual calls for:
Stock: NGK CR7EH-9
(.031-.035)
Optional: NGK CR8EH-9
8-12k miles interval

Plugs installed by PO NGK CR9EH-9 (cooler for sustained high speed)
12K+ miles

I ordered set of NGK CR7EH-9

Spark Plug wires may be original (70k+ miles; 20 years); some sources say OEMs are inferior to what's now available.

Recommendations/sources welcome for replacement plug wires

UPDATE; I swapped knock sensors. Code 25 stays with harness?

Brad,

I am sorry to hear that you're still getting error code 25 after swapping sensors. Have you gone through the trouble shooting process outlined in the Honda Service manual?

Unfortunately, this error code is usually never the result of a faulty knock sensor. It usually means one of two things, you have a broken or damaged wire between the left knock sensor and the ECM or a part in the ECM has gone bad. In my case, it was latter. Ultimately, I elected to purchase a new ECM. However, I should note that Honda no longer manufactures this ECM for pre '08 STs. I did, however, find a supplier in Japan that had a police ECM in stock. That ECM can be used in place of the civilian model. But it does limit the top speed of the ST to 120 miles per hour. This was not an issue for me, but concerns about the limiter have been expressed on the forum.

While I wasn't comfortable doing this, many have continued to ride their STs without replacing the ECM. Although it will lessen fuel economy, most swear they don't notice much of a difference. @Igofar believes operating the bike with the error code is damaging. It's his observation that STs with damaged ECMs run hotter, which can damage and melt plastics. YMMV.

Good luck on your diagnostics.

Chris

 

[eyrepb]

Am going thru manual troubleshooting. 5-47 states:


Don't we want continuity from the knock sensor connector 1P to the ECM connector? If so (YES), wouldn't that be a closed circuit? Am I misunderstanding something?

 

[Buckeyechris]

Am going thru manual troubleshooting. 5-47 states:


Don't we want continuity from the knock sensor connector 1P to the ECM connector? If so (YES), wouldn't that be a closed circuit? Am I misunderstanding something?

Brad,

You are correct. Continuity is what should be the result if the wiring is sound and intact.

This represents one of the quirks that sometimes happens with publications by Mother Honda. Something got lost in translation. Whether it is a Japanese to English issue or an Engineer to Publisher issue, I cannot be sure. It's been one of my frustrations for years. Nevertheless, the HSM is correct at least 90 percent or more, so I just go with it. If I don't think it's correct, I check with other sources. Thankfully, ST-Owners is a very supportive forum and people more knowledgeable and skilled than I have been willing to help me out. I'm just trying to give you the limited benefit of my experience. A certain level of aptitude is always helpful, and your aptitude is rightfully questioning the folks at Honda. While they're really good, they're not perfect.

Chris