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DTC/P0144

P0144: O2 Sensor Circuit High Voltage (Bank 1, Sensor 3)

Quick Answer
Moderate SeveritySafe to drive (short-term)Emissions

P0144 means the third oxygen sensor on bank 1, fitted after a second (usually under-floor) catalytic converter, is reporting a voltage that stays too high for too long, above roughly 1.0V. Only a minority of cars have a Sensor 3, typically petrol engines built to the strictest emissions standards with two catalysts in series; most cars have two sensors per bank and cannot set this code.

Estimated repair costFrom €65 to €800+, varies by vehicle

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What does P0144 mean?

P0144 means the third oxygen sensor on bank 1, fitted after a second (usually under-floor) catalytic converter, is reporting a voltage that stays too high for too long, above roughly 1.0V. Only a minority of cars have a Sensor 3, typically petrol engines built to the strictest emissions standards with two catalysts in series; most cars have two sensors per bank and cannot set this code.

P0144 is a emissions-related diagnostic trouble code classified as moderate severity. When your vehicle's ECU detects this condition, it stores P0144 and illuminates the check engine light.

What are the symptoms of P0144?

If your vehicle has triggered P0144, you may notice one or more of these symptoms:

  • Check engine light illuminated
  • Increased fuel consumption in some cases
  • Possible failed emissions test
  • Usually no noticeable change in driveability
  • May appear alongside catalyst codes such as P0420

What causes P0144?

Here are the most common causes of P0144:

high: Failed Bank 1 Sensor 3 stuck at high voltage
medium: Genuine rich condition reaching Sensor 3 (leaking injector, high fuel pressure)
medium: Short to voltage in the Sensor 3 signal wire
medium: Sensor element contamination (oil, coolant, silicone)
low: Failing secondary catalyst no longer storing oxygen

Is it safe to drive with P0144?

Generally yes, for short-term driving. Safe to drive short term. Sensor 3 is a monitoring sensor after a second catalytic converter and does not drive fuel mixture, but persistent high voltage may signal a genuine rich condition or contamination that should be diagnosed within a few weeks.

How do you diagnose P0144?

Follow these steps to pinpoint the root cause of P0144:

  1. Confirm the vehicle's exhaust layout. Sensor 3 is only present on cars with a third oxygen sensor after a second catalytic converter
  2. Read freeze frame data and look for companion codes (P0172, P0175, P0420) that indicate a real rich condition or catalyst issue
  3. Check long-term fuel trims. Significantly negative LTFT (under -10%) suggests a genuine rich condition rather than a faulty sensor
  4. Inspect the Sensor 3 signal wire for shorts to voltage, especially near heat shields and chassis power runs
  5. Substitute a known-good sensor. If high voltage persists, the issue is upstream (fuel mixture or wiring)

How much does P0144 cost to fix?

Repair costs for P0144 vary depending on the root cause and your vehicle. Here are typical estimates:

Repair Parts Cost Labor Cost Total Estimate DIY Difficulty
Replace Bank 1 Sensor 3 €50–€220 €60–€160 €110–€380 Moderate
Repair shorted sensor wiring €5–€30 €60–€150 €65–€180 Moderate
Diagnose and fix rich condition (injector, fuel pressure, contamination) €30–€500 €80–€300 €110–€800 Professional

Prices estimated as of March 2026. Costs vary by region, vehicle, and shop.

These codes are often seen alongside P0144 or indicate related issues:

P0143P0145P0146P0147P0420P0138

Common questions about P0144

Why does my car have three O2 sensors per bank?

Some petrol cars built to the strictest emissions standards have a second catalytic converter further down the exhaust, with a third oxygen sensor after it to monitor it. Most passenger cars only have two sensors per bank.

Can I drive with P0144?

Yes, short term. Sensor 3 is a monitoring sensor and does not drive fuel mixture decisions. If the underlying issue is a real rich condition though, prolonged driving wastes fuel and may damage the catalyst stages over time.

Where is Bank 1 Sensor 3 located?

After the second catalytic converter on bank 1, usually under the car and further back along the exhaust than Sensor 2. The exact position varies by model, so confirm it in the service information before ordering a sensor.

How do I know if the sensor or the engine is at fault?

Check long-term fuel trims. A negative LTFT under -10% means the engine is genuinely running rich, so the sensor is reporting correctly. A normal LTFT around 0% with stuck-high Sensor 3 voltage means the sensor itself or its wiring has failed.

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