GM Engine Coolant Temperature Sensor Replacement – GMC Chevy 1998 K1500 ECT Sensor Code P0118 Repair

MaxiLink ML629:
ECT Sensor:
Dielectric Grease:

This video walks through the process of diagnosing and replacing a faulty engine coolant temperature sensor (ECT Sensor). The vehicle being repaired in this video is a GMC 1998 K1500 with a 350 Vortec engine. The symptoms that were being produced by this faulty ECT sensor include.

The 1998 K1500 engine would stall when I put the vehicle in gear.
The engine would race or surge up in RPMs and then die back to a stall or near stall.
If the vehicle stalled, I had to open the throttle all the way (push the gas pedal to the floor) in order to get it to start again.

The issue was diagnosed using a Maxilink ML629 code scanner. when viewing live data, the ECT sensor was displaying negative temperature values. The engine would also react to gentle hammer taps on the ECT sensor, which was another indication that the ECT was not providing correct temperature values to the computer.

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