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Home >> Toyota >> 2004 >> ECHO 2D Sedan, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Diagnostics >> DTC Tests >> DTC P0115: Engine Coolant Temperature Circuit, DTC P0117: Engine Coolant Temperature Circuit Low Input, DTC P0118: Engine Coolant Temperature Circuit High Input >> Circuit Description
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Circuit Description

A thermistor is built in the engine coolant temperature sensor and changes the resistance value according to the engine coolant temperature.

The structure of the sensor and connection to the ECM is the same as those of the intake air temperature sensor.

HINT:

If the ECM detects the DTC "P0115, P0117 or P0118", it operates the fail-safe function in which the engine coolant temperature is assumed to be 80°C (176°F).

Fig 1: DTC Detection Condition Table
G02905070Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

HINT:

After confirming DTC "P0115, P0117 or P0118", use the hand-held tester or the OBD II scan tool to confirm the engine coolant temperature from the "DIAGNOSIS/ENHANCED OBD II/DATA LIST/ALL".

TEMPERATURE DISPLAYED SPECIFICATION

Temperature Displayed Malfunction
-40 °C (-40 °F) Open circuit
140°C (284°F) or more Short circuit