Hello Fit people! This is my first post here on your domain. My girlfriend drives an '08 Fit and has had it for a couple months. I am in the process of troubleshooting what appeared to be an overheating issue but now looks like a potential miscommunication with the ECU. That's just my thoughts, but I will share my process here so please let me know what you think.

The car overheated while my girlfriend was driving on the highway as indicated by the red temperature light. She stopped at her destination before driving it home about two hours later (about a 10 minute drive). She reported low power/hesitation on the drive home.

The car is hard to start, cranking for ~15 seconds before firing. It has not lost coolant or oil. Both fluids are at a good level and look pretty clean. The heater blows hot so I assume the water pump is creating flow. The passenger side radiator fan (AC condenser fan) was not coming on, even it when it had power. So I changed it and now it works fine. The red temperature light still comes on, even at idle. When it comes on, the engine doesn't appear hot. I can put my hand on the engine block and it's about the same as body temperature. Other times the red temperature light comes on immediately after the engine is started. I live in Canada and it's ~0°C outside right now.

As far as I can tell from reading the forums, the ECT 1 sensor communicates with the instrument cluster, and the ECT 2 turns on the radiator fans. The fans seem to be operating normally once the engine warms up. So my suspicion is with the ECT 1 sensor.

I removed and inspected the thermostat, ECT 1*, and ECT 2*.

*ECT 1 and 2 for reference.

The thermostat opens between 75-80°C as it should, and I checked the resistance of both ECT sensors at a range of temperatures. They were consistent with the resistance chart I found on the Honda-Tech* forum and other similar charts.

*Resistance chart from Honda-Tech forum

Could the ECT 1 sensor be causing the light to come on even if it has good resistance? Is the resistance a reliable test of its condition?

Locally, the sensor is about $70 so I don't want to just change it.

Any other leads for diagnosis are appreciated.

Thanks,
Me

 

Update - It was the ECT 1 sensor (highlighted yellow). Changed it and it solved the problems I was having.

Here's the sensor on Rock Auto: https://www.rockauto.com/en/moreinfo...t=4748&jsn=377

 

Thank you for posting the update, I'm also having a similar problem. Did the car still have a hard time starting after you replaced the sensor?

 

@réalmichael: Good work, my friend. Thoughtfully done.