P0117 Honda Civic
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 Honda Civic 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 Honda Civic.
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 Honda Civic.
Common Causes on Honda Civic
- Failed Engine Coolant Temperature (ECT) sensor (shorted internally)
- Damaged wiring between ECT sensor and PCM
- Corroded ECT sensor connector
- Coolant leak causing sensor to read incorrectly
Symptoms
- Check Engine Light on
- Cooling fans running constantly
- Gauge reads maximum temperature immediately on start
- Rich running condition and poor fuel economy
Notes for Honda Civic
Honda ECT sensors are inexpensive and easy to replace — they thread into the thermostat housing; just drain a bit of coolant first.