P0116 Code: Engine Coolant Temperature Sensor Range/Performance
🟠 Moderate severity · drivable
You can drive, but watch the temperature gauge and expect worse fuel economy until the cause is fixed.
What P0116 means
The engine coolant temperature (ECT) sensor tells the computer how warm the engine is. This code means the sensor reading does not match expected values, such as coolant temperature changing too slowly. The engine may run rich, use more fuel, or have trouble starting.
Symptoms
- Check engine light on
- Poor fuel economy
- Hard starting
- Engine takes long to warm up
- Rough idle
Common causes
- most common: Thermostat stuck open
- common: Faulty ECT sensor
- common: Low coolant level
- less common: Wiring or connector issues
How to fix it
| Fix | DIY? | Typical cost |
|---|---|---|
| Replace the thermostat | Yes | $30–120 |
| Replace the ECT sensor | Yes | $20–80 |
| Top up coolant and fix leaks | Yes | $10–50 |
| Repair the wiring or connector | Yes | $20–80 |
Frequently asked questions
Can I drive with P0116?
Yes, but watch the temperature gauge. The engine may run rich and use more fuel until the cause is fixed.
Why does a stuck-open thermostat cause this?
The coolant never gets hot enough, so the sensor reading stays low and the computer thinks the sensor is faulty.
How do I know if my thermostat is stuck open?
If the engine takes a very long time to warm up or the heater stays cool, the thermostat may be stuck open.
Related codes
P0115
P0115 Code: Engine Coolant Temperature Circuit Malfunction
P0117P0117 Code: Engine Coolant Temperature Circuit Low Input
P0128P0128 Code: Coolant Thermostat (Coolant Temperature Below Regulating Temperature)
Updated 2026-08. This page is informational and not a substitute for professional diagnosis.