What causes fault code P0144?

• Most likely: Faulty Oxygen (O2) sensor (internal short in sensor 3) • Likely: Short to voltage in the wiring harness between the sensor and ECM • Possible: Corrosion or water ingress in the sensor connector terminals • Rare: Faulty Engine Control Module (ECM) or an extremely rich fuel condition (e.g., leaking fuel injector)

How do you fix fault code P0144?

STEP 1: Visually inspect the sensor connector for corrosion or fluid contamination. STEP 2: Use a scan tool to monitor O2 sensor 3 voltage in live data. If voltage stays above 1.2V, proceed to Step 3. STEP 3: Disconnect the sensor. If the voltage on the scan tool drops to a default value (e.g., 0.45V), the sensor is shorted internally. If voltage stays high, check the wiring harness for a short to 12V power. STEP 4: Replace the O2 sensor (Bank 1 Sensor 3). Clear codes and perform a road test.

Powertrain (Engine & Gearbox)Standard EOBD

P0144 - O2 Sensor Circuit High Voltage (Bank 1 Sensor 3)

Q: What are the symptoms of fault code P0144?

• Check engine light (MIL) illumination • Often no noticeable driveability symptoms (sensor 3 is post-catalyst) • Slight decrease in fuel economy • Failed emissions test

Last updated:1 February 2026

Related:Oxygen Sensor (Lambda), SCR Catalyst, Wiring Harness, Engine Control Unit (ECU)

System

Powertrain (Engine & Gearbox)

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Technical Description

P0144 diagnostic trouble code (DTC) is defined as 'O2 Sensor Circuit High Voltage (Bank 1 Sensor 3)'. This occurs when the Engine Control Module (ECM) detects that the signal voltage from the third oxygen sensor on bank 1 remains above the normal operating range (typically exceeding 1.2 volts). This sensor is used primarily to monitor the efficiency of the catalytic converter. High voltage on this circuit usually indicates a short to voltage in the wiring harness or a failure within the sensor's internal ceramic element that causes the signal line to bias high.

Possible Causes

Faulty Oxygen (O2) sensor (internal short in sensor 3)

Short to voltage in the wiring harness between the sensor and ECM

Corrosion or water ingress in the sensor connector terminals

Faulty Engine Control Module (ECM) or an extremely rich fuel condition (e.g., leaking fuel injector)

Symptoms

Check engine light (MIL) illumination

Often no noticeable driveability symptoms (sensor 3 is post-catalyst)

Slight decrease in fuel economy

Failed emissions test

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P0144 - O2 Sensor Circuit High Voltage (Bank 1 Sensor 3)

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P0144 - O2 Sensor Circuit High Voltage (Bank 1 Sensor 3)

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