P0115 Engine Coolant Temperature Sensor Circuit 1 Malfunction

OBD2 Code: P0115

Description: Engine Coolant Temperature Sensor Circuit 1 Malfunction

Definition: This code indicates that the engine control module (ECM) has detected a malfunction in the circuit of the engine coolant temperature sensor, which is responsible for monitoring the temperature of the engine’s coolant. The ECM uses this information to adjust fuel injection and ignition timing for optimal performance and emissions. A fault in this circuit can lead to poor engine performance and increased emissions.

p0115 – Engine Coolant Temperature Sensor Circuit 1 Malfunction

Typical Severity: Moderate

Common Causes

P0115 – Engine Coolant Temperature Sensor Circuit 1 Malfunction

Common Causes:

• Defective engine coolant temperature sensor
• Open or short in the engine coolant temperature sensor circuit
• Poor electrical connection related to the engine coolant temperature sensor circuit
• Faulty engine control module (ECM)

 

Common Misdiagnosis

OBD2 Code: P0115

Description: Engine Coolant Temperature Sensor Circuit 1 Malfunction

Common Misdiagnosis: Replacing the engine coolant temperature sensor without checking for wiring issues or a faulty thermostat.

 

Common Diagnostic Steps

OBD2 Code: P0115

Description: Engine Coolant Temperature Sensor Circuit 1 Malfunction

• Verify the presence of the code using an OBD2 scanner.
• Inspect the engine coolant temperature sensor and its wiring for any visible damage or disconnection.
• Check the coolant level to ensure it is at the appropriate level, as low coolant can affect sensor readings.
• Test the engine coolant temperature sensor with a multimeter to verify it is functioning correctly. Compare resistance values against manufacturer specifications.
• Examine connectors and pins for corrosion or bent pins that could cause poor connections.
• If applicable, inspect and test related fuses and relays for functionality.
• Clear the code from the vehicle’s computer system after repairs are made, then perform a road test to see if the code returns.