Controller shows Fault Code 1511 – Coolant Temperature Sensor Circuit Fault

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

Possible Causes

Open or shorted coolant temp sensor wiring, Failed coolant temperature sensor, Corroded connector at sensor

Safety first: Disable automatic start and allow the engine to cool before touching coolant components.

Wiring inspection: Follow the harness from the coolant temperature sensor to the ECM. Repair any damaged sections.
Connector: Clean and reseat the sensor connector. Look for coolant intrusion into the connector body.
Sensor replacement: Drain enough coolant to remove the sensor if necessary. Install a new Cummins coolant temperature sensor and refill/bleed the system.
Reset: Clear the fault and verify stable temperature readings during operation.

Medium 3/5

Coolant Temperature Sensor

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