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P0125 Fault on Saturn SC1: Diagnosis and Solutions for Coolant Temperature Sensor Issues

Model: Saturn SC1 Fault Code: P0125 Posted: 2015-01-23 20:46

My grandfather's 2003 Saturn SC1 has a P0125 diagnostic trouble code illuminated. The vehicle will not start and is running rich on fuel. We have already replaced the fuel pump, fuel filter, fuel injectors, and the coolant temperature sensor (ECT), but the issue persists. The P0125 code indicates 'insufficient coolant temperature for closed-loop fuel control'. What other potential causes could be responsible? Please share insights based on known Saturn SC1 technical specifications.

Related fault codes
P0125
Comments (1)
Anonymous 2015-01-24 13:10

Inspect the wiring harness connected to the ECT sensor to ensure proper connectivity and no corrosion. Verify that the thermostat is functioning correctly and reaches the standard operating temperature of 195°F—ensure it is not stuck open or missing entirely. Additionally, use a noid light to test fuel injectors for any signs of sticking (shorted to ground). Also check the fuel pressure regulator (FPR): ensure there is no fuel present in the vacuum line connected to the FPR, as this could indicate a leak or malfunction.