P0144 OBD2 Code Guide
P0144 is a powertrain diagnostic trouble code. Use this hub to understand the plain meaning, the first checks to run, and which vehicle-specific guides may be more useful before replacing parts.
O2 Sensor Circuit High Voltage (Bank 1, Sensor 3)
Code P0144 indicates that the Powertrain Control Module (PCM) has detected a consistently high voltage signal from the third oxygen sensor in Bank 1. Bank 1 refers to the engine bank containing cylinder #1. Sensor 3 is typically located after the secondary catalytic converter, if present, or is simply the third sensor in the exhaust stream for monitoring purposes. A high voltage signal usually suggests a rich exhaust condition or, more commonly with this specific code, a short to voltage in the sensor's signal circuit, a faulty sensor, or an issue with the sensor's internal heater circuit causing an erroneous reading. This sensor's primary role is to monitor the efficiency of the catalytic converter and contribute to fuel trim adjustments in some systems.
Code verification standard
P0144 is published with SAE J2012 / ISO 15031-6 code structure plus OBD2 P0144 diagnostic context.
First checks
- - Read all stored and pending codes before clearing anything.
- - Save freeze-frame data so you know speed, load and temperature when the code set.
- - Inspect wiring, connectors, fuses, hoses and obvious leaks tied to the named system.
- - Compare live data against realistic values before buying sensors or modules.
- - Clear the code only after repair and complete a drive cycle to confirm it does not return.
P0144 diagnostic path
- 1Connect an OBD-II scan tool to confirm the P0144 code and check for any other related diagnostic trouble codes (DTCs). Record freeze frame data.
- 2Visually inspect the Bank 1, Sensor 3 oxygen sensor and its wiring harness for any signs of damage, fraying, corrosion, or loose connections. Pay close attention to any potential shorts to power or ground.
- 3Using a scan tool, monitor the live data stream for Bank 1, Sensor 3 voltage. A healthy zirconia O2 sensor should fluctuate between approximately 0.1V and 0.9V. A P0144 code typically means the voltage is stuck consistently high (e.g., above 0.9V or even at battery voltage).
- 4Perform voltage drop tests and continuity checks on the sensor's signal wire and heater circuit wiring between the sensor connector and the PCM connector to identify any open circuits, shorts, or excessive resistance.
- 5If wiring is intact, disconnect the sensor and check the sensor's internal resistance (if applicable) and the heater circuit resistance. A high voltage reading with the sensor disconnected might indicate a short to voltage in the wiring or a PCM issue.
Verify before repair
- - Replace the faulty Bank 1, Sensor 3 oxygen sensor. This is the most common resolution if the sensor itself is internally shorted or failing.
- - Repair or replace damaged wiring and/or connectors leading to the Bank 1, Sensor 3 oxygen sensor.
- - Diagnose and repair any short to voltage in the O2 sensor signal circuit that is causing the consistently high voltage reading.
- - Address any underlying engine rich condition that might be causing the sensor to accurately report a high voltage, though this is less common for a P0144.
Vehicle-specific pages to check next
Searches this page covers
These queries are answered in this guide without creating thin duplicate pages.