The engine temperature sensor on a Cummins diesel engine is critical for keeping operating temperatures in a safe range. When the sensor or its wiring fails, the engine may enter a derate mode, lose power, or run inefficiently. Understanding how to troubleshoot and maintain this component can prevent downtime and costly repairs.
The Cummins temperature sensor affects several systems:
l Cooling fan operation
l Turbo boost control logic
l Fuel injection volume
l Exhaust aftertreatment temperatures (DPF & SCR systems)
l Idle speed regulation
Because the sensor ties into emissions and safety systems, sensors are calibrated with high accuracy.
If the sensor malfunctions, the ECM may activate fault codes such as:
|
Fault Code |
Description |
|
111 |
Coolant Temperature High |
|
1761 |
Coolant Temperature Sensor – Voltage Out of Range |
|
373 |
Engine Fan Control Signal Issue |
A scan tool or Cummins INSITE software is helpful for pinpointing the problem.
Low coolant can cause incorrect temperature readings.
→ Refill and check for leaks.
Look for:
Cracked insulation
Broken connectors
Corrosion in terminals
Compare ohm values versus Cummins temperature-resistance charts.
If reading does not match → Replace sensor.
If wiring and sensor are good, the ECM input circuit may be damaged.
Professional diagnosis is required in this case.
Always perform the replacement when the engine is cool.
Use thread sealant or factory-approved sealing washer.
After installation, run engine and verify temperature rises smoothly.
Clear fault codes using diagnostic tools.
Maintain fresh coolant with correct chemical balance.
Avoid mixing coolant types (can cause corrosion).
Keep engine ground connections clean to prevent electrical issues.
Replace coolant hoses before they become brittle.
Low-quality substitutes may have incorrect resistance characteristics, causing:
l Poor fuel efficiency
l Overheating risks
l False warning codes
l Premature ECM failures
Investing in a high-quality Cummins-compatible sensor ensures accurate, stable engine control.