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Home >> Lexus >> 2007 >> SC 430 >> Repair and Diagnosis >> Engine Performance >> Engine Control System >> SFI System >> DTC P0125 Insufficient Coolant Temperature for Closed Loop Fuel Control >> Description
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DTC P0125 Insufficient Coolant Temperature for Closed Loop Fuel Control: Description

Fig 1: Insufficient Coolant Temperature Resistance Graph
G05291338Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

A thermistor is built into 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 as the Intake Air Temperature (IAT) sensor.

HINT:

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

DTC DETECTION CONDITION CHART

DTC No. DTC Detection Condition Trouble Area
P0125 Engine coolant temperature change is minimal for 96 seconds after engine start (2 trip detection logic)
  • Engine coolant temperature sensor
  • Cooling system
  • Thermostat
P0125 Engine coolant temperature change is minimal for 142 seconds after engine start (2 trip detection logic)
  • Engine coolant temperature sensor
  • Cooling system
  • Thermostat
P0125 Engine coolant temperature change is minimal for 20 minutes after engine start (2 trip detection logic)
  • Engine coolant temperature sensor
  • Cooling system
  • Thermostat

HINT:

Confirm the ECT using the intelligent tester. Enter the following menus: DIAGNOSIS / ENHANCED OBD II / DATA LIST / PRIMARY / COOLANT TEMP.

TEMPERATURE DISPLAYED MALFUNCTION REFERENCE CHART

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