Hi,

I was trying to diagnos the check engine light for my cousin's 95 max, and it reads "0103", which is coolant temp sensor. Can anyone tell me what this is and is it easy to fix/replace, and how much does it cost?

Thanks a lot.

-Phil

 

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Recalling from my Oldsmobile days, I had to replace the coolant tempearture sensor because the car would overheat when I was in stop and go traffic. Once in motion at 30 mph or so, it was fine.

The coolant temperature sensor is responsible for sending a signal to the ECM when the coolant heats up to a certain temperature. The ECM will then trip a relay connected to the cooling fan near the radiator, increasing the air flow in the engine bay and cooling the engine. Thus preventing overheating, lots of steam and embarassment on the side of a highway as people rubber neck.

TMAX

 

The Engine Coolant Temperature Sensor sends a signal to the Engine Control Module (the computer) which indicates how warm the engine is. The ECM responds by instructing the fuel injection system to deliver a richer mixture when the engine is cold. This is similar to the function of a choke on a carbureted engine.

The ECTS is located in the coolant outlet pipe at the rear of the left (front) cylinder head. There is a good photo of it in the Haynes manual on page 6-12. This part is easy to reach and replacement is a job which can be done by the home mechanic. I don't know the price, but believe this to be one of the less expensive engine sensors.