DTC P0119: Engine Coolant Temperature Sensor Circuit Intermittent

In the intricate realm of automotive diagnostics, diagnostic trouble codes (DTCs) act as guiding stars, illuminating potential issues within a vehicle’s systems. Among these, DTC P0119 takes center stage as a significant indicator of problems related to the intermittent behavior of the Engine Coolant Temperature (ECT) Sensor circuit. This comprehensive article delves into the causes, symptoms, inspection procedures, and effective solutions for addressing and resolving DTC P0119.

1. Causes of DTC P0119:

DTC P0119 emerges when the Engine Control Module (ECM) detects intermittent fluctuations in the Engine Coolant Temperature (ECT) Sensor circuit. The underlying causes can encompass:

– Faulty Engine Coolant Temperature Sensor: A sensor with sporadic malfunctions or intermittent connections can lead to erratic data transmission.

– Wiring and connector issues: Damaged, corroded, or loose wiring and connectors within the ECT sensor circuit can cause intermittent signal disruptions.

– Temperature sensor placement: Incorrect placement or insecure sensor positioning can result in intermittent signal loss.

– ECM communication problems: Intermittent ECM malfunctions or communication breakdowns can result in inconsistent ECT sensor data.

2. Symptoms of DTC P0119:

Recognizing the symptoms associated with DTC P0119 aids mechanics in accurately diagnosing the issue:

– Erratic engine performance: Inconsistent temperature data can lead to imbalanced air-fuel mixture and sporadic engine power fluctuations.

– Unpredictable fuel efficiency: Intermittent temperature readings can result in varying fuel consumption patterns.

– Intermittent rough idling or stalling: Inaccurate temperature measurements can cause the engine to intermittently idle roughly or stall.

– Illuminated Check Engine Light (CEL): DTC P0119 triggers the CEL to alert the driver of a potential intermittent problem.

3. Inspection of DTC P0119:

Thorough inspection techniques are crucial for accurate diagnosis:

– OBD-II scan: Utilize an OBD-II scanner to retrieve the DTC and accompanying freeze frame data, providing insight into the conditions that activated the code.

– Visual examination: Inspect the Engine Coolant Temperature Sensor, wiring, and connectors for visible signs of damage, contamination, or corrosion.

– ECT sensor testing: Verify the sensor’s resistance during both normal and intermittent conditions using a multimeter.

4. Resolving Causes of DTC P0119:

Addressing DTC P0119 involves specific steps tailored to the underlying issue:

– Engine Coolant Temperature Sensor replacement: Replace a malfunctioning sensor with a new, high-quality unit that meets manufacturer specifications.

– Wiring and connector repair: Repair or replace damaged wiring and connectors to ensure consistent signal transmission.

– Sensor placement inspection: Verify proper sensor positioning and secure attachment to prevent intermittent signal loss.

– ECM diagnosis: If an ECM malfunction is suspected, diagnose and rectify the issue through reprogramming or replacement.

5. Clearing DTC P0119:

After successfully addressing the root cause, clear the DTC from the ECM’s memory using an OBD-II scanner. This step confirms the issue’s resolution and prevents the recurrence of the CEL.


DTC P0119, indicative of an intermittent Engine Coolant Temperature Sensor circuit, requires meticulous attention to detail. Through a comprehensive understanding of its causes, recognition of its symptoms, thorough inspection techniques, and effective solutions, mechanics can accurately diagnose and rectify this issue. Maintaining consistent and reliable engine temperature readings remains essential for ensuring optimal combustion, performance, and the overall reliability of the vehicle.