Code
P0144
GWM
P — Powertrain
- High oxygen sensor circuit voltage (bank 1, sensor 3)
AI status
Completed
Completed
100%
Causes
- Damaged or shorted sensor wiring or connector (short to battery or open/ground)
- Faulty oxygen sensor (contaminated, failed internal element)
- Heater circuit fault in the sensor (open or shorted heater)
- Exhaust leaks near the sensor creating false readings
- Engine running excessively rich or fuel system fault affecting sensor voltage
- ECM/input circuit fault or poor ground
Symptoms
- Check Engine/MIL illuminated
- Possible poor fuel economy or failed emissions test
- Irregular or fixed oxygen sensor voltage for the affected sensor on live data
- Possible loss of closed-loop fuel control (depending on other sensor data)
- Occasional rough idle or drivability complaints if fuel system affected
What to check
- Retrieve freeze frame and full DTC list; verify P0144 is current and note conditions
- View live O2 sensor data (Bank1 Sensor3) and compare to Bank1 Sensor1 (upstream) while engine at operating temperature
- Inspect sensor connector and wiring for damage, corrosion, pulled pins, or evidence of heat/soot
- Check for exhaust leaks near the sensor flange or pipe joints
- Backprobe sensor signal and measure voltage with a DVOM and/or oscilloscope during steady idle and under load
- Check heater circuit supply and ground for expected voltages and measure heater resistance per vehicle specs
Signal parameters
- Expected narrowband O2 sensor voltage range: ~0.1–0.9 V (typical)
- Downstream (sensor 3) normally shows less switching than upstream; often steady ~0.1–0.6 V depending on catalyst state
- High-voltage threshold that can set code: sustained readings near or above ~0.9 V or lack of expected signal activity (manufacturer-specific)
- Heater circuit resistance typically a few ohms to tens of ohms (refer to GWM spec)
- Supply voltage to heater circuit: typically battery voltage when key on — verify against vehicle spec
Diagnostic algorithm
- Confirm code and operating conditions with scan tool; warm engine to normal temp before testing.
- Visually inspect sensor, connector, and wiring for damage, corrosion, or heat exposure. Repair any obvious damage.
- With backprobe or breakout adapter, monitor Sensor3 signal with engine idling and under throttle. Note voltage behavior and compare to Bank1 Sensor1. Look for stuck-high (>0.8–0.9 V) or no activity.
- Check heater circuit: with key ON measure supply voltage at connector and measure heater resistance at sensor. Replace sensor if heater open or outside spec.
- Check for wiring faults: test continuity to ECM, check for shorts to battery or ground, and inspect grounds. Repair any open or shorted circuits.
- Test sensor response: create a controlled rich condition (briefly introduce propane or disconnect vacuum per safe procedures) and observe if Sensor3 voltage changes. Lack of response points to sensor/wiring/ECM issue.
- Inspect for exhaust leaks upstream of the sensor and repair if found; retest after repair.
- If wiring and heater OK but sensor signal still abnormal, replace Bank 1 Sensor 3 with OE or equivalent and clear codes. Road test to confirm code does not return.
- If problem persists after replacement, verify ECM input pin operation or consult manufacturer-specific wiring and ECM diagnostics.
Likely causes
- Wiring/connector short to power or poor ground at Bank 1 Sensor 3
- Failed/deteriorated Bank 1 Sensor 3 (contaminated or aged)
- Open/short in the sensor heater circuit
- Exhaust leak upstream of the sensor causing abnormal voltages
Fault status
Status
Oxygen sensor circuit voltage abnormal or no activity detected — Bank 1 Sensor 3 (high/erratic voltage or no switching).
Repair difficulty: Medium
Diagnostic time: 0.5 - 2.0 hours
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