ECTS (Engine Coolant Temperature sensor) is NTC thermister which voltage gets low if the temperature comes to be high. It is installed on cylinder head where coolant passage is in order to sense engine coolant temperature. ECM controls fuel injection adaptation and operating time of preheater with ECTS information. Especially, it is the most important factor to control fuel injection adaptation at cold starting. therefore, it gives influence to cold starting when ECTS is faulty. Furthermore, ECM regards Engine Coolant Temperature as 80℃ then, controls fuel amount when ECTS is faulty and engine is "ON". And, ECM controls fuel injection amount after it regards as -10℃ at cranking. The cooling fan controlled by engine coolant temperature operates constantly with HIGH-MODE prevent engine from overheating during engine "ON" but auxiliary heater does not operates at all.

P0118 is set when the voltage above 3.255V - maximum output voltage of ECTS - is detected for more than 2.0 sec. This code is due to open or short to battery in signal circuit or open in ground circuit.