P0125

DTC P0125 Engine Coolant Temperature (ECT) Sensor - Engine Coolant Temperature Excessive Time To "Closed Loop":

Engine Coolant Temperature (ECT) Sensor:

CIRCUIT DESCRIPTION
While the engine is warming, the Vehicle Control Module-A (VCM-A) monitors the Engine Coolant Temperature (ECT) sensor to determine how long it takes the engine to reach the coolant temperature required for "Closed Loop" operation. A DTC P0125 will set if the VCM-A determines that the engine does not reach "Closed Loop" temperature in a specified amount of time. This test will not be run if either intake air or engine coolant temperature are below a predetermined temperature. The VCM-A will only run this DTC on a cold start and only once per cold start. DTC P0125 is a type "B" DTC.

DTC PO125 WILL SET WHEN
^ No ECT sensor tests failing or DTC's set.
^ No Intake Air Temperature (IAT) sensor DTC's set.
^ Vehicle speed is greater than 5 mph.
^ ECT is greater than -17°C (1.4°F).
^ Start-up ECT is less than 35°C (95°F).
^ "Closed Loop" timer is at least 4 minute 20 seconds.
^ IAT is greater than -15°C (5°F).
^ Minimum stabilized ECT is less than 20°C (68°F).

ACTION TAKEN (VCM-A WILL DEFAULT TO)
The VCM-A will turn "ON" the Malfunction Indicator Lamp (MIL) after two consecutive driving cycles with the fault active.

DTC P0125 WILL CLEAR WHEN
The VCM-A will turn the MIL "OFF" after three consecutive trips without a fault condition present. A history DTC will be cleared if no fault conditions have been detected for forty warm-up cycles [coolant temperature has risen 22°C (40°F) from start-up coolant temperature and engine coolant temperature exceeds 71°C (160°F) that same ignition cycle] or the Tech 1 clearing feature has been used.

DTC CHART TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.
1. This test checks engine warm-up rate.
2. This test checks coolant sensor reading on Tech 1 scan tool and actual coolant temperature.

DIAGNOSTIC AIDS
DTC P0125 indicates a skewed ECT sensor or engine thermostat that is not operating correctly.

An intermittent may be caused by a poor connection, rubbed through wire insulation or a wire broken inside the insulation.

Check for:
^ Poor connection or damaged harness - Inspect VCM-A harness connectors for backed out terminals "RE23" and "GR4" improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wire connection and damaged harness.
^ Intermittent test - If connections and harness check OK, monitor a digital voltmeter connected between VCM-A terminal "RE23" and "UR4" while moving related connectors and wiring harness. If the failure is induced, the voltage reading will change. This may help to isolate the location of the malfunction.