Engine Coolant Temperature Sensor 1 Circuit Range/Performance
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.
Can I keep driving? Drivable, but expect harder cold starts and worse fuel economy while the ECM works off a bad temperature reading.
Real-world scan data
Appears alongside · share of P0116 scans
Figures reflect only diagnostic scans recorded through our own apps and tools. Cars are typically scanned because a symptom or warning light prompted it, so these counts describe our scan records — not the incidence of faults in any model, and not the quality, reliability, or safety of any vehicle. No comparison between manufacturers or models is implied. All trademarks belong to their respective owners; no affiliation or endorsement is implied.
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?+
Can I just clear P0116?+
Related codes
Read & clear P0116 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.