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P0128 Diagnostic Trouble Code Discussion for April 2011

Thermostat System Malfunction

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Trouble Ticket Help Requests for DTC P0128
Help Request Posted
2003 Chevrolet Trailblazer LT 4.2L MIL Lamp on VIN: 1GNDT13S23
P0128: Engine Coolant Temperature Below Thermostat Regulating Temperature. ... P1481 which was a fan speed loss of signal code. So I replaced the fan clutch and there is now a fan speed signal to the PCM. But now I have this P0128 code. It does have a new thermostat that is about 3 months old or so. Sitting in the shop running it was...
April 05, 2011