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Home >> Lexus >> 2005 >> SC 430 >> Repair and Diagnosis >> Engine Performance >> System >> SFI System - Diagnostics >> DTC P0125: Insufficient Coolant Temperature For Closed Loop Fuel Control >> Circuit Description
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Circuit Description

A thermistor is built in the Engine Coolant Temperature (ECT) 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 the Intake Air Temperature (IAT) sensor.

HINT:

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

Fig 1: Coolant Temperature Graph
G02955432Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
Fig 2: Coolant Temperature Circuit Description Table
G02955433Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002