Service Bulletin 70 and 71

I Was having a surging issue at idle and a stall issue when shifting into neutral. Never had any codes or alarms with this issue. Brought the 2003 BF225 to a shop and they had trouble at first reading the motor with their computer. Finally got it to read and it showed a bad HO2 sensor. They replaced it and cleaned a bunch of stuff. Got the boat back and it runs great. Unfortunately, now I'm getting the infamous alarm for the HO2 sensor. I read the codes and found the HO2 sensor is faulty. Brought it back to the shop and they confirmed the code is the HO2 sensor. They called Honda and Honda apparently didn't know what to do. Shop tells me nothing they can do and Honda doesn't know either.

I completed the service bulletin #56 the other day and reset the code in the ECM. I did not replace the HO2 sensor again because it's a week old and I just didn't want to throw another $170 at the motor just yet. Ran the boat and the alarm comes on still. Will replacing the brand new HO2 sensor with another new one fix the problem or am I stuck with this problem. Is there anything else I can do? I have researched this and saw that many people have this HO2 sensor alarm issue, but I can't seem to find anyone who completely fixed the problem. I saw something about SB 70 and 71, but couldn't find if this is the fix for my 2003 BF225 HO2 sensor issues?

SB70 details an updated sensor and ECM which can cope with higher temps and water mist but it seems it's only applicable to serial numbers after 1400000 (so NOT 1000001 ~ 1309999).

Honda SB 70 applies to SN's from BAGJ-1000001 ~ 1509999.

SB 71 applies to SN BAGJ-1600001 ~ 1600527

According to SB # 70, the only fix for your model (SN < 1309999) is to replace the HO2 sensor. If you need a copy of SB 70, send an e-mail to me at [email protected].

Also, if you have a copy of SB #56, re-read page 7 for proper operating techniques for mitigating HO2 failures. Biggest problem is engine mounted too low.

I should have made myself clearer - SB70 does cover the earlier engines but does not provide a fix (other than replacing the failed sensor) unless your serial number is > 1400000

Thank you gentlemen. I will email you to get that SB 70. I guess I'm just frustrated because the sensor is brand new and throwing a code. I did run the boat once with the new sensor but not the new exhaust pipes so maybe that one trip somehow got water in there and damaged the new sensor. As far as motor height, I have a 20" shaft. When I run a cruising speeds, the cavitation plate is just at or slightly above water line which is what I've read is prefect. I think I do need to raise the motor though because the exhaust ports are not the 5.9" above the water like Honda recommends. I'm worried though that my motor will cavitate a lot more if I raise it any. I guess I have to try.

when back boat in water or coming off plane I always trim motor up so as now to back flush exhaust and have water get to h2o sensors..between 56 an th have ad no issues with sensors

Is it possible that you have a faulty spark plug or cylinder that is misfiring and the O2 sensor is seeing that occurrence and is operating out of range...causing the code?

Mike

The spark plugs are only a couple months old (not to say that one couldn't be bad). Will a misfire show symptoms, hesitation, loss of power, etc? The motor seems to be running good though. Do you check for a misfire with a compression check? The shop told me it was the HO2S again. I wonder if their computer actually pinpoints the fault or if it just gives them a few options of what it could be like the Honda manual does. The alarm comes on after about 15 minutes. If I stop and restart the motor right away, the alarm comes on right away. If I stop and let the motor cool down, it takes some time for the alarm to come on again. So, it appears the alarm is coming on when the motor is hot or at its hottest running temperature.

If I stop and restart the motor right away, the alarm comes on right away.

Click to expand...

On my engine (with a presumed faulty O2 sensor) if I stop the engine and restart it straight away the fault will not return for 3-4 minutes if I stay at idling speeds - if I run higher than idling speeds the fault does not come back until I start idling again. I don't know whether this means something or not - maybe my engine doesn't have a faulty O2 sensor!
You should be grateful a new sensor is 'only' $170 - here in the UK they are the equivalent of about $450

Here is what can throw a "1" fault code: (1) A failed HO2 sensor, (2) a misfiring spark plug, (3) a failed or failing coil (usually when they warm up), (4) low fuel pressure.

Have your shop first test the fuel pressure. It should be between 41 and 48 psi - engine at idle, in gear, and prop removed.

Also have them test the coils.

Make sure your plugs are ONLY NGK IZFR6F11. The "I" in front of the "Z" stands for iridium tipped. They are the ones you need. I've seen folks install the NGK ZFR6F11 plugs, which will work for a short while. The NGK IZFR6F11 plugs will cost between $15.00 and $30.00 USD each.

If all of that checks out, then you need to replace the HO2 sensor.

As I stated earlier, in SB #56, re-read page 7 for proper operating techniques for mitigating HO2 failures. Biggest problem is engine mounted too low. Second biggest problem is coming off plane too fast, as Aristikat pointed out.