2003 Mercury Grand Marquis OBD2 Code P0197 Engine Oil Temperature (EOT) Sensor Low

P0197 code definition

Engine Oil Temperature (EOT) Sensor Low

What the P0197 code means

This code specifically means that the resistance value the powertrain control module (PCM) sees is low in comparison to the predefined specifications. This can possibly be due to high engine oil temperature.

What causes the P0197 code?

• Faulty engine oil temperature sensor
• Short to ground in the EOT circuit
• Faulty PCM
• High engine oil temperature

What are the symptoms of the P0197 code?

The only symptom is a Check Engine Light. The EOT system is there to detect other problems with your 2003 Mercury Grand Marquis . If the circuits of the EOT system have problems it will be unable to monitor the oil temperature.

How does a mechanic diagnose the P0197 code?

This code most likely indicates a short to ground in the EOT electrical system. A scan tool should be used to observe sensor data to confirm this condition. Direct testing of the EOT circuits with a multimeter should be performed to pinpoint the source of the short to ground.

Each section of wiring should be isolated and tested to determine which section of wiring is damaged. This is followed by carefully inspecting the wiring harness for damage. Often, it is necessary to wiggle the suspected harness while observing the scan tool or multimeter to watch for a change in resistance value.

Common mistakes when diagnosing the P0197 code

• Replacing the sensor without checking the wiring going to and from the EOT sensor
• Failing to check the reference voltage that the PCM provides to the sensor

How serious is the P0197 code?

The code itself is not serious. It will not leave an owner stranded on the side of the road. However, if the system is left unrepaired, it is possible that severe engine damage could occur if the EOT system is unable to monitor troubles that arise with the oil temperature.

What repairs can fix the P0197 code?

• Replacing the EOT sensor
• Repairing any damaged wiring in the EOT circuit
• Repairing damage or worn sensor connectors
  
• PCM repair or replacement

Additional comments for consideration regarding the P0197 code

A P0197 code is a generic code that all manufacturers can use and must always retain the same definition.

Each manufacturer utilizes a different diagnostic method for the testing of this system. Even then, it is often used in performance 2003 Mercury Grand Marquis s that are designed to be driven very hard. Driving in racing conditions pushes your 2003 Mercury Grand Marquis to the limits of its engineering beyond what an everyday driver will experience. For this reason, an EOT system is not common on most 2003 Mercury Grand Marquis s.

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P0197

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