What causes fault code P0145?

• Most likely: Faulty or aged oxygen sensor (Bank 1, Sensor 3) • Likely: Corrosion or poor connection in the sensor connector • Possible: Exhaust leak near the sensor location • Rare: Damaged wiring harness (rubbing against chassis) • Rare: Failed sensor heater circuit

Powertrain (Engine & Gearbox)Standard EOBD

P0145 - O2 Sensor Circuit Slow Response (Bank 1, Sensor 3)

Q: What are the symptoms of fault code P0145?

• Check engine light (MIL) illuminated • No noticeable drivability issues (sensor is mainly for catalyst monitoring) • Failed emissions test • Slight increase in fuel consumption (rare for sensor 3)

Q: How do you fix fault code P0145?

STEP 1: Visually inspect the sensor connector for corrosion or water ingress. Clean as necessary. STEP 2: Inspect the exhaust system for leaks near the sensor location; even small leaks can cause false slow response readings. STEP 3: Monitor the sensor signal using a scan tool (Live Data) or oscilloscope. At operating temperature, ensure the voltage transitions between 0.1V and 0.9V as expected. STEP 4: Measure heater circuit resistance (typically 5–20 Ohms). Ensure the sensor is receiving 12V and ground for the heater. STEP 5: If wiring and exhaust are intact, replace the Oxygen Sensor (Bank 1, Sensor 3) and clear DTCs.

Last updated:1 February 2026

Related:Lambdasensor (Oxygen Sensor), Catalytic Converter, Engine Control Unit (ECU/ECM), Avgassystem

System

Powertrain (Engine & Gearbox)

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Mass or Volume Air Flow A Circuit Malfunction

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P0102

Mass Air Flow (MAF) Circuit Low Input

P0103

Mass or Volume Air Flow Circuit High Input

Technical Description

P0145 is set when the Engine Control Module (ECM) detects that the heated oxygen sensor (HO2S) – Bank 1, Sensor 3 – is reacting too slowly to changes in the exhaust gas oxygen content. During specific driving cycles, the ECM monitors the sensor voltage (typically 0.1V to 0.9V). If the response time to transitions between lean and rich conditions exceeds the calibrated threshold, the code is triggered. This sensor is primarily used to monitor catalytic converter efficiency.

Possible Causes

Faulty or aged oxygen sensor (Bank 1, Sensor 3)

Corrosion or poor connection in the sensor connector

Exhaust leak near the sensor location

Damaged wiring harness (rubbing against chassis)

Failed sensor heater circuit

Symptoms

Check engine light (MIL) illuminated

No noticeable drivability issues (sensor is mainly for catalyst monitoring)

Failed emissions test

Slight increase in fuel consumption (rare for sensor 3)

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P0145 - O2 Sensor Circuit Slow Response (Bank 1, Sensor 3)

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P0145 - O2 Sensor Circuit Slow Response (Bank 1, Sensor 3)

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