P0125-L32 only or P0128

WARNING: This page is about a different car, the 2006 Buick LaCrosse and 2006 Buick Allure. However, it is still accessible from the selected car via links, so may be relevant.

IMPORTANT: The cooling fans are commanded ON when certain ECT DTCs are set.

Inspect the cooling system coolant level. If low, then refer to Loss of Coolant .
Inspect for the following conditions:
- Corrosion on the ECT terminals
- Improper or corroded terminals at the ECT harness connector
- Loose terminals in the ECT harness connector
Measure for 4.8-5.2 volts from the signal circuit of the ECT sensor to a good ground with a DMM.
- If not within specified range, test the ECT sensor signal circuit for high resistance or for an intermittent and for a poor connection at the control module. If circuits test OK, then replace the control module.
Measure for 4.8-5.2 volts from the signal circuit of the ECT sensor to the low reference circuit of the ECT sensor with a DMM.
- If not within specified range, test the ECT sensor low reference circuit for high resistance or for an intermittent and for a poor connection at the control module.
- If circuits test OK, then replace the control module.
Turn OFF the ignition. Remove the ECT sensor. Place the sensor on a work surface away from any heat source.
Allow the sensor to reach ambient air temperature for 30-60 minutes.
Observe and record the ambient air temperature of the vehicle environment using an accurate thermometer.

IMPORTANT: DO NOT hold the ECT sensor by the probe.

At the sensor, measure the resistance between the ECT signal and the ECT low reference terminals with a DMM and record the value.
Compare the resistance measurement of the ECT sensor to the ambient air temperature on the Temperature vs Resistance .
- If within the specified range, then install the ECT sensor and refer to Testing for Intermittent Conditions and Poor Connections .
- If NOT within the specified range, then replace the ECT sensor.