What it means
Engine coolant temperature sensor 3 is reporting a signal below its expected range. 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 signal to a control module, which monitors that circuit for a usable temperature reading. This code sets when the sensor 3 signal is lower than the expected electrical range, often because the signal is being pulled toward ground; sensor 3's location varies by vehicle.
Common causes
Most likely first.
- Signal wire shorted to ground
- Connector pins corroded - high contact resistance
- Harness chafing through insulation
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 compare sensor 3 live data with other coolant-temperature readings, especially with the engine cold.
- Locate sensor 3 using vehicle service information and inspect its signal wire for chafing or contact with ground.
- Check the connector for corrosion, moisture, damaged terminals, or a poor connection that could create high resistance.
- Test the sensor 3 signal circuit for a short to ground and check supply and ground circuits according to the manufacturer's information.
- If the wiring is sound, test the sensor itself against the manufacturer's specification.
Common fixes
- Repair chafed sensor 3 wiring that is shorting to ground.
- Clean corroded connector pins and restore a secure connection.
- Repair damaged signal, supply, or ground wiring.
- Replace coolant temperature sensor 3 if it fails testing.
Can I keep driving?
A low sensor 3 signal can mislead fan or warm-up control, so drive only while monitoring engine temperature and cooling fan behavior. Stop if the engine overheats or the fan is not working 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.