Engine Coolant Temperature Circuit Malfunction

FAULT ID
P0115

TITLE
Engine Coolant Temperature Circuit Malfunction

BACKGROUND
- The engine coolant temperature sensor converts the engine coolant temperature to a voltage and outputs it,
- The engine control module checks whether the voltage is within a specified range. In addition, it checks the engine coolant temperature (signal) does not drop while the engine is warming up.

RANGE OF CHECK (1)
- Ignition switch: ON
- Excluding 60 seconds after the ignition switch is turned to ON or immediately after the engine starts.

SET CONDITIONS (1)
- Sensor output voltage is 4.6 V or more (corresponding to an engine coolant temperature of -45°C (-49° F) or less for 4 seconds.

or

- Sensor output voltage is 0.1 V or less (corresponding to an engine coolant temperature of 140°C (284°F) or more) for 4 seconds.

RANGE OF CHECK (2)
- Ignition switch: ON
- Engine speed is approx. 50 RPM's or more.

SET CONDITIONS (2)
- The sensor output voltage increases from 1.6 V or less (corresponding to an engine coolant temperature of 40°C (104°F) or more) to 1.6 V or more (corresponding to an engine coolant temperature of 4O°C (104°F) or less).
- After this, the sensor output voltage is 1.6 V or more for 5 minutes.

RANGE OF CHECK (3)
- Engine coolant temperature is 20°C (68° F) or more when the engine is started.
- Intake air temperature is 20°C (68° F) or more when the engine is started.

SET CONDITIONS (3)
- The engine coolant temperature takes 5 minutes or more to rise to approximately 50°C (122°F) after the engine is started.

EFFECT
Limp-in
- Controls as if the engine coolant temperature is 80°C (176°F).

PROBABLE CAUSES
- Engine coolant temperature sensor failed.
- Open or shorted the engine coolant temperature sensor circuit, or loose connector.
- Engine control module failed.