What it means
Engine coolant temperature sensor 3 has an intermittent or erratic signal. The code does not specify the sensor's location or function; these depend on the vehicle.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
Coolant temperature sensor 3 sends a changing temperature signal to a control module, which checks that it remains stable and plausible. This code sets when the signal becomes intermittent or erratic; sensor 3's location and function depend on the vehicle.
Common causes
Most likely first.
- Connector loose or corroded
- Connector with intermittent contact under vibration
- Harness routed against vibrating component
Symptoms
- Check engine light on
- Cooling fan runs constantly or not at all
- Cabin heater weak or excessively hot
- Possible long warm-up time or hard cold start
How to diagnose it
- Save freeze-frame data and review sensor 3 live data for sudden jumps or dropouts, comparing it with other temperature readings.
- Locate sensor 3 using vehicle service information and inspect its connector for looseness, corrosion, or damaged terminals.
- Follow the sensor 3 harness and look for chafing or contact with a vibrating or moving component.
- With live data displayed, gently move the connector and accessible harness sections to see whether the reading changes.
- If the wiring and connector remain sound, test sensor 3 and its circuit under the manufacturer's procedure for intermittent faults.
Common fixes
- Secure a loose sensor 3 connector and repair damaged terminals.
- Clean corrosion from the sensor 3 connector and restore firm contact.
- Reroute or repair harness sections chafed against vibrating components.
- Replace sensor 3 if testing confirms an intermittent internal fault.
Can I keep driving?
Drive cautiously and keep an eye on the temperature gauge, since an erratic sensor 3 signal can cause unreliable fan or warm-up control. Stop if the engine overheats or the fan does not operate when required.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.