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What does Error Code P0151 mean?

Moderate Issue
DTC Code P0151 indicates a low voltage issue in the O2 Sensor Circuit for Bank 2 Sensor 1. This occurs when the ECM detects the Heated Oxygen Sensor (HO2S) voltage is less than 50 mV, suggesting a potential short to ground.

What are the symptoms of Error Code P0151?

  • Engine Light ON: The check engine light or service engine soon warning light illuminates, indicating an issue with the O2 sensor circuit on Bank 2 Sensor 1.
  • High Fuel Consumption: The vehicle may experience increased fuel consumption due to incorrect air-fuel mixture readings from the O2 sensor.
  • Excessive Smoke from Exhaust: There may be excessive smoke emitted from the exhaust, which can be a result of improper combustion caused by faulty O2 sensor readings.

What causes Error Code P0151?

  • The front heated oxygen sensor on Bank 2 may be faulty, leading to incorrect voltage readings.
  • An open or shorted harness in the front heated oxygen sensor on Bank 2 can disrupt the circuit.
  • Poor electrical connections in the front heated oxygen sensor circuit on Bank 2 can cause low voltage signals.
  • Variations in fuel system pressure, either low or high, can affect sensor readings.
  • Contaminated fuel can lead to improper combustion and affect sensor performance.
  • Faulty fuel injectors may cause incorrect air-fuel mixture, impacting sensor voltage.
  • Exhaust gas leaks can alter the oxygen levels detected by the sensor.
  • Engine vacuum leaks can lead to incorrect air-fuel ratios, affecting sensor output.
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How to fix Error Code P0151?

  • Verify DTC Code: Confirm the presence of DTC P0151 using an OBD-II scanner. Ensure no other related codes are present.
  • Inspect Wiring and Connectors: Visually inspect the wiring and connectors for the O2 sensor on Bank 2 Sensor 1. Look for signs of damage, corrosion, or disconnection.
  • Check Sensor Voltage: Using a multimeter, measure the voltage at the O2 sensor connector. A low voltage reading confirms the issue. Compare with manufacturer specifications.
  • Test Sensor Heater Circuit: Verify the heater circuit of the O2 sensor is functioning. Check for continuity and proper resistance values as per the service manual.
  • Inspect Exhaust for Leaks: Examine the exhaust system for leaks near the O2 sensor, which could affect sensor readings.
  • Replace O2 Sensor: If all tests confirm the sensor is faulty, replace the Front Heated Oxygen Sensor (HO2S) Bank 2 Sensor 1.
  • Clear DTC and Test Drive: Clear the DTC code and perform a test drive to ensure the issue is resolved and the code does not return.
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