2002 Land Rover Discovery II OBD2 Code P0144 O2 Sensor Circuit High Voltage (Bank 1, Sensor 3)

P0144 code definition

O2 Sensor Circuit High Voltage (Bank 1 Sensor 3)

What the P0144 code means

P0144 is the OBD-II generic code which indicates that the Engine Control Module (ECM) has detected excessively high voltage from the bank 1 sensor 3 O2 sensor circuit, indicating a rich condition.

What causes the P0144 code?

• The O2 sensor bank 1 sensor 3 is the sensor after the last catalyst. A rich condition may be a problem with the catalyst not cleaning the exhaust. This can be caused by a broken up catalyst.

• The ECM detects a short to power in the circuit for the O2 from a wiring or sensor problem.

What are the symptoms of the P0144 code?

• The code will cause the ECM to turn on the check engine light.

• The ECM does not use this sensor for fuel control but for a catalyst monitor only and should not cause a direct impact on the engine performance.

How does a mechanic diagnose the P0144 code?

• Checks the electrical connections or wire harness cover to the O2 bank 1 sensor 3 for shorts or sensor damage

• Scans codes and documents freeze frame data, then clears codes to verify the sensor failure

• Monitors O2 sensor data to see if the voltage is stuck above 500 mV

• Checks the exhaust catalyst for damage or if it broke apart in the housing

• Follows the manufacturer's specific pinpoint tests for further diagnosis

Common mistakes when diagnosing the P0144 code

Follow these simple guidelines to prevent mistakes:

• Check the catalyst integrity for any damage before replacing the O2 sensor

• Check the O2 sensor for oil or coolant contaminants that may short the sensor from engine leaks

• Scan the replacement O2 sensor to make sure the heater circuit works properly

• Check the removed O2 sensor for damage from a defective catalyst that will cause sensor failure

How serious is the P0144 code?

• The code may cause the engine to fail emission testing.
• The code may indicate a problem with the catalyst and it may block the exhaust.

What repairs can fix the P0144 code?

• Clearing the fault codes and performing a road test to try and verify failure

• Replacing the shorted O2 sensor for bank 1 sensor 3

• Repairing or replacing the shorted wiring or connection to the O2 sensor for bank 1 sensor 3

• Replacing the broken catalyst

Additional comments for consideration regarding the P0144 code

The O2 sensor signal circuit for bank 1 sensor 3 is used to monitor the catalyst efficiency and does not affect the fuel control of the engine.

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