O2 Sensor Circuit High Voltage Bank 2 Sensor 1
The Powertrain Control Module (PCM) has detected that the voltage signal from the upstream oxygen sensor on Bank 2 (Sensor 1) remains excessively high for a prolonged period. This high voltage typically indicates a continuous rich exhaust condition or a short to voltage within the sensor's wiring circuit.
While the vehicle will usually remain drivable, a persistent rich condition can eventually damage the catalytic converter and foul spark plugs. It should be diagnosed and repaired soon to prevent more expensive secondary failures.
Common symptoms
- Illuminated Check Engine Light
- Decreased fuel economy
- Rough idle or engine stalling
- Black smoke from the tailpipe
- Engine hesitation or sluggish acceleration
Likely causes
- Faulty Bank 2 Sensor 1 Oxygen (O2) sensor
- Short to voltage in the O2 sensor signal circuit
- Leaking fuel injector on Bank 2
- Excessive fuel pressure
- Restricted engine airflow or faulty MAF sensor
- Faulty Powertrain Control Module (PCM)
What to check before replacing parts
Connect a scan tool and monitor the Bank 2 Sensor 1 live data.
Look for: Look for the O2 sensor voltage to be stuck above 0.9 volts without fluctuating when the engine is warm and running.
Visually inspect the wiring harness and connector for the Bank 2 Sensor 1 O2 sensor.
Look for: Check for melted wires, chafing, or corrosion that could cause a short to voltage or poor connection.
Monitor short-term and long-term fuel trims for Bank 2 using a scan tool.
Look for: If fuel trims are highly negative (pulling fuel), the engine is genuinely running rich, pointing to a fuel delivery issue rather than a sensor circuit fault.
Disconnect the O2 sensor and measure the signal wire voltage from the PCM.
Look for: With the sensor unplugged and key on, the bias voltage should be around 0.45V; if it shows 12V or 5V, there is a short to voltage in the wiring harness.
Test fuel pressure and inspect for leaking injectors on Bank 2.
Look for: Fuel pressure exceeding manufacturer specifications or a rapid drop in resting pressure indicates a mechanical fuel issue causing the rich condition.
This page explains the generic P0152 definition and is general reference information, not a diagnosis for your specific vehicle. Actual causes, severity, and repairs vary by make, model, engine, and mileage — always confirm with a scan tool and a qualified technician before replacing parts.
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