P0117 Hyundai Sonata
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 Hyundai Sonata 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 Hyundai Sonata.
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 Hyundai Sonata.
Common Causes on Hyundai Sonata
- Failed engine coolant temperature (ECT) sensor reading low
- Short circuit in ECT sensor wiring harness
- Corroded ECT sensor connector
- ECM ground issue causing incorrect voltage reference
Symptoms
- Check Engine Light on
- Fans running constantly at high speed
- Gauge reads cold even when engine is warm
- Rich fuel mixture and poor economy
Notes for Hyundai Sonata
The ECT sensor is inexpensive and easy to reach on most Hyundai engines; replace rather than troubleshoot.