P0117 GMC Sierra 1500
Engine Coolant Temperature Sensor Circuit Low · Powertrain Code · Medium · Repair: Easy
What is P0117?
The coolant temperature sensor is reading lower than expected — possible open circuit or faulty sensor.
When the GMC Sierra 1500 triggers code P0117 (engine coolant temperature sensor circuit low), it typically points to an issue in the powertrain system. Below you'll find the most common causes, symptoms, and repair options specific to the GMC Sierra 1500.
This repair is rated easy, meaning basic tools, no lift needed.
Diagnostic data on this page is compiled from publicly available repair resources and technical service bulletins. Always have a qualified mechanic confirm the diagnosis before authorizing repairs on your GMC Sierra 1500.
Common Causes on GMC Sierra 1500
- Failed Engine Coolant Temperature (ECT) sensor (common wear item)
- Shorted wiring in the ECT sensor circuit
- Corroded ECT sensor connector due to coolant seepage
- Low coolant level causing sensor to read incorrectly
Symptoms
- Check Engine Light on
- Electric cooling fans may run continuously
- Gauge may read erratically or peg high
- Poor cold-start fuel economy
- Engine may not enter closed-loop fuel control
Notes for GMC Sierra 1500
The ECT sensor on GM vehicles is inexpensive and easy to replace — do not overlook low coolant as a root cause, especially on 1.5T engines with known head gasket seepage.