intermittent overheat false alarm

Honda 150 hp and I have false intermittent overheat alarms happening. They occur with the thermostats out and with the thermostats in the engine. Pee stream is strong, temps read on the metal of the T Stat housings is well below “hot” (123 / 135 degrees). The alarm is continuous and the only light lit is the water temp light. Here’s what happens.

Start the engine. Engine runs fine for about a minute and alarm goes off, engine goes into safe mode. Shut off engine, immediately restart, runs fine for a minute or so, alarm goes off, etc. Immediately restart, engine runs fine, no alarms. Sometimes it runs fine after the first restart. SOmetimes it requires 3 or 4 restarts before running fine. Most of the time it runs fine without any alarms or messing with restarts.

I’m thinking bad sensor? Anyone else dealt with this problem in the past? Is there a way to test the individual sensors or do I need to have my dealer read codes? Engine is still in warranty.

Thnaks, Tom

Hi Tom,
I think you have answered your own question, take the motor to your Honda dealer and let them sort it out for you. There are resistace values for the temp senders, but due to the inconsistant nature of your problem, I dont believe that is the cause. i think the biggest problem you will have is duplicating the problem at the dealers.

Cheers
John

dinghyworld said:

i think the biggest problem you will have is duplicating the problem at the dealers.
John

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Exactly! I talked to the dealer. I'm going to clean all the sensor connections first. There was heat sensor on the exhaust manifold that I didnt know about. The last DIY step before I load it on the trailer and drag it up the road is to remove and clean the sensors.

It ran fine for 6 hours from startup through running and trolling yesterday and then a few minutes after beginning the run back home the O'Heat alarm went off. Cycled theough restart twice and then it was fine for the 20 mile run back home. Geeze I hate these kinds of problems.

Tom

What did the problem turn out to be? Having similar issues with our Honda 225.