P0144
O2 Sensor Circuit High Voltage (Bank 1, Sensor 3)
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The P0144 code indicates that the voltage from the third oxygen sensor on Bank 1 is persistently higher than the normal operating range. An O2 sensor typically produces a voltage between 0.1V and 0.9V, with higher voltages indicating a rich exhaust condition (more fuel, less oxygen). When the signal stays stuck near or above the high end, the PCM logs this trouble code.
As with the other Sensor 3 codes, this sensor monitors the output of a secondary catalytic converter on Bank 1. Drivability impacts are typically minimal since this sensor doesn't directly control fuel trim. The primary consequence is a check engine light and an emissions test failure. However, if the high voltage reading is caused by a genuine rich-running condition, you may notice increased fuel consumption.
Start your diagnosis by checking the sensor's wiring harness for shorts, especially where wires may rub against metal components or other wiring. If the wiring is intact, replace the O2 sensor. If the code returns after replacement, investigate whether the engine is running rich due to other issues like leaking fuel injectors, a faulty fuel pressure regulator, or excessive oil consumption.
Severity
Symptoms
- •Check engine light is on
- •Vehicle fails emissions testing
- •Possible slight increase in fuel consumption
- •Faint rich exhaust smell
- •No major changes in engine performance
Likely Causes
The oxygen sensor's sensing element has degraded and is stuck producing a high voltage output, falsely indicating a constant rich exhaust condition.
A wiring fault where the signal wire contacts a power source will force the voltage reading high regardless of actual exhaust oxygen content.
If the engine is genuinely running very rich due to a fuel system issue, the sensor may be accurately reading high oxygen consumption in the exhaust.
Oil or fuel contamination on the sensor element can cause it to read artificially high, especially if there is an internal engine issue like worn piston rings.
Estimated Cost
Professional Repair
Includes parts + labor
Common Fixes
- Replace the O2 sensor (Bank 1, Sensor 3)
- Repair short circuits in the signal wiring
- Address underlying rich-running condition if present
- Fix oil leaks or consumption issues that may contaminate the sensor