DTC P0197: Engine Oil Temperature Sensor ‘A’ Circuit Low

In the intricate world of automotive diagnostics, diagnostic trouble codes (DTCs) serve as guiding lights, illuminating potential issues within a vehicle’s systems. Among these, DTC P0197 takes center stage as a significant indicator of problems related to the Engine Oil Temperature Sensor ‘A’ circuit low. This comprehensive article delves into the causes, symptoms, inspection procedures, and effective solutions for addressing and resolving DTC P0197.

1. Causes of DTC P0197:

DTC P0197 emerges when the Engine Control Module (ECM) detects a low input signal in the Engine Oil Temperature Sensor ‘A’ circuit. The underlying causes can encompass:

– Faulty Engine Oil Temperature Sensor ‘A’: A malfunctioning or out-of-spec sensor can produce abnormally low temperature readings.

– Wiring and connector problems: Damaged or corroded wiring and connectors within the sensor circuit can lead to signal issues.

– Open circuit: A break in the sensor circuit can result in a lack of signal transmission.

– Coolant leaks: Coolant leaks near the sensor can lead to incorrect readings.

2. Symptoms of DTC P0197:

Recognizing the symptoms associated with DTC P0197 aids mechanics in accurately diagnosing the issue:

– Inaccurate engine oil temperature readings: Faulty sensor ‘A’ can lead to incorrect temperature calculations.

– Decreased engine performance: Low temperature sensor ‘A’ readings can lead to inadequate engine management.

– Illuminated Check Engine Light (CEL): DTC P0197 triggers the CEL to alert the driver of a potential problem.

3. Inspection of DTC P0197:

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 Oil Temperature Sensor ‘A’ wiring and connectors for visible signs of damage or corrosion.

– Coolant leak check: Inspect for coolant leaks near the sensor that could impact its accuracy.

4. Resolving Causes of DTC P0197:

Addressing DTC P0197 involves specific steps tailored to the underlying issue:

– Engine Oil Temperature Sensor ‘A’ 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 accurate signal transmission.

– Coolant leak repair: Address any coolant leaks near the sensor to prevent future inaccuracies.

5. Clearing DTC P0197:

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 P0197, indicative of a low input signal in the Engine Oil Temperature Sensor ‘A’ circuit, underscores the importance of accurate sensor readings for optimal engine performance. By comprehending its causes, recognizing its symptoms, employing meticulous inspection techniques, and implementing effective solutions, mechanics can accurately diagnose and rectify this issue. Ensuring reliable sensor performance remains pivotal for achieving optimal engine functionality, fuel efficiency, and overall vehicle operation.