Q21-6007S | Genuine Paccar® Engine Coolant Level Sensor

1. Detects Coolant Level

• Measures whether the coolant in the tank or radiator is at the proper height.

2. Sends a Signal to the Car’s Computer

• If the coolant drops below a safe level, it notifies the Engine Control Module (ECM) or instrument cluster.

3. Triggers Dashboard Warning Light

• Activates a “Low Coolant” or “Check Coolant Level” warning on the dashboard.

4. Helps Prevent Overheating

• Low coolant can cause the engine to overheat.

• The sensor acts as an early warning system before serious engine damage occurs.

1. “Low Coolant” Warning Light Stays On

• The dashboard warning appears even when the coolant reservoir is full.

• This is the most common symptom of a faulty sensor.

2. “Low Coolant” Warning Comes On and Off Randomly

• The light may flicker or activate only on bumps or sharp turns.

• Often caused by a sensor that’s dirty, sticking, or failing internally.

3. No Warning When Coolant Is Actually Low

• A dangerous symptom.

• The sensor fails to alert you, which can lead to engine overheating.

4. Overheating Without a Coolant Warning

• If the sensor doesn’t detect low coolant, the engine may overheat without any early indication.

5. Faulty or Inconsistent Readings

• The sensor may send incorrect or unstable signals to the ECM or instrument cluster.

• A scan tool might show erratic coolant level messages.

6. Check Engine Light (Less Common)

Some vehicles may set a diagnostic code if the coolant level signal is missing or invalid.

7. Corroded or Damaged Sensor Connector

• Wiring or connector damage can mimic a bad sensor.

• May cause intermittent or weak signals.