P0116
Engine Coolant Temperature Sensor 1 Circuit Range/Performance
Engine coolant temperature
Generic OBD-II
High
What it means
P0116 means the engine coolant temperature signal is within a working range but doesn't behave plausibly — for example, it doesn't rise as the engine warms up. Because the ECM uses this reading to set cold-start fueling, a bad signal can cause hard cold starts and poor fuel economy. Common causes are a failing coolant temperature sensor or a stuck-open thermostat.
High
Can I keep driving? Drivable, but expect harder cold starts and worse fuel economy while the ECM works off a bad temperature reading.
Common symptoms
What you'll notice
- Check-engine light on
- Harder starting when cold
- Reduced fuel economy
- Temperature gauge reading incorrectly or the engine not warming up as expected
Common causes
Most likely first
- Faulty engine coolant temperature (ECT) sensor (most common)Likely
- Stuck-open thermostat keeping coolant below normal temperatureCommon
- Damaged or corroded wiring or connector at the sensorCommon
- Low coolant level so the sensor isn't fully immersedLess often
How to diagnose & fix
Work through it in order
- Check the coolant level and top up if low.
- Compare the ECT reading against intake-air temperature on a cold start — they should match when the engine is cold.
- Inspect the sensor connector and wiring for corrosion or damage.
- Test the thermostat if the engine is slow to warm up.
- Replace the ECT sensor if its reading is out of range. Clear and re-test.
FAQ
Quick answers
Is it safe to drive with P0116?+
Yes, but a wrong coolant-temperature signal can richen the mixture and hurt fuel economy, and a stuck thermostat can affect warm-up — so don't leave it indefinitely.
Can I just clear P0116?+
It returns once the ECM sees the implausible reading again. The sensor, thermostat, or wiring cause has to be fixed.
Related codes
Often seen with P0116
Read & clear P0116 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX