5 Signs of a Faulty Coolant Temperature Sensor

The coolant temperature sensor (CTS) plays a vital role in your vehicle’s engine management system. It sends real-time temperature data to the ECU (Engine Control Unit), helping manage fuel injection, ignition timing, and cooling system behavior.

1. Erratic Temperature Gauge Readings

If your dashboard temperature gauge jumps around or shows abnormal readings, it could be due to a faulty coolant temperature sensor. This can cause the engine to run inefficiently, leading to further issues.

2. Poor Fuel Economy

A failing CTS can cause your car to inject too much fuel, assuming the engine is still cold. This rich mixture leads to poor fuel economy. For a visual guide on how this affects your system, watch our full video here.

3. Engine Overheating

When the CTS fails to send the correct signals, the radiator fan may not engage, or the engine may not reduce power in time. This can lead to dangerous engine overheating. Learn more by checking this YouTube Short on overheating symptoms.

4. Hard Starting or Stalling

Incorrect temperature data may cause hard starts or engine stalling, especially in cold weather. This is a common but overlooked symptom of a bad coolant temp sensor.

5. Check Engine Light Activation

A malfunctioning CTS often triggers the Check Engine Light. A quick scan using an OBD-II scanner might show a CTS-related error code. Here’s a helpful video snippet explaining this further.

Why the Coolant Temperature Sensor Matters

The CTS ensures your engine runs at the optimal temperature. Ignoring signs of failure may lead to:

• Increased fuel consumption
• Engine misfires
• Emissions test failure
• Severe engine damage from overheating

Tips for Maintaining a Healthy CTS

• Schedule regular coolant system inspections
• Replace coolant according to your vehicle’s service manual
• Use quality replacement sensors when necessary

Need a Visual Explanation?

Watch our complete video breakdown on identifying the signs of a bad coolant temperature sensor below:

Or view our YouTube Short here for a 30-second summary.

Conclusion

From poor fuel economy to check engine lights, a failing coolant temperature sensor can have wide-reaching effects. Replacing or testing your CTS is an easy and affordable step to keep your engine running smoothly.