P0152 OBD2 Code Guide
P0152 is a powertrain diagnostic trouble code. Use this hub to understand the plain meaning, the first checks to run, and which vehicle-specific guides may be more useful before replacing parts.
O2 Sensor Circuit High Voltage (Bank 2, Sensor 1)
Code P0152 indicates that the Engine Control Module (ECM) or Powertrain Control Module (PCM) has detected a consistently high voltage signal from the upstream oxygen sensor on Bank 2 (the engine bank that does not contain cylinder #1). This sensor, also known as Sensor 1, is located before the catalytic converter and is crucial for monitoring the air-fuel ratio. A high voltage typically signifies a rich condition (too much fuel), but in the context of a "circuit high voltage" code, it often points to an electrical fault within the sensor itself, its wiring, or a short to voltage, rather than an actual excessively rich exhaust. This prevents the PCM from accurately adjusting fuel trims, leading to potential issues with fuel economy, emissions, and engine performance.
Code verification standard
P0152 is published with SAE J2012 / ISO 15031-6 code structure plus OBD2 P0152 diagnostic context.
First checks
- - Read all stored and pending codes before clearing anything.
- - Save freeze-frame data so you know speed, load and temperature when the code set.
- - Inspect wiring, connectors, fuses, hoses and obvious leaks tied to the named system.
- - Compare live data against realistic values before buying sensors or modules.
- - Clear the code only after repair and complete a drive cycle to confirm it does not return.
P0152 diagnostic path
- 1Visually inspect the Bank 2, Sensor 1 oxygen sensor and its wiring harness for any signs of damage, fraying, corrosion, or melting that could indicate a short to voltage or ground. Ensure the connector is securely seated and free of debris.
- 2Using a multimeter, back-probe the O2 sensor signal wire (typically a black or blue wire) at the sensor connector or PCM connector. With the engine running and warmed up, check for a constant voltage reading above 1.0 volt. Also, check the heater circuit for proper voltage supply and ground.
- 3Disconnect the O2 sensor and check for continuity and resistance in the sensor's signal and heater wires back to the PCM. Look for any shorts to power (12V) or ground within the harness, which would cause a high voltage reading.
- 4Utilize a professional scan tool to monitor live data for Bank 2, Sensor 1. Observe the O2 sensor voltage readings. If the voltage is consistently stuck high (e.g., 1.2V or higher) and does not fluctuate, it strongly suggests a sensor or wiring fault. Compare its behavior to Bank 1, Sensor 1 if available.
Verify before repair
- - Replace the faulty Bank 2, Sensor 1 oxygen sensor. This is the most common fix if the sensor itself has an internal electrical short or has failed.
- - Repair or replace damaged, corroded, or shorted wiring and connectors leading to the Bank 2, Sensor 1 O2 sensor.
- - Diagnose and repair any short to voltage in the O2 sensor signal circuit, which could be caused by chafed wiring contacting a power source.
- - Address any underlying severe engine rich condition if diagnostic steps confirm the sensor is accurately reporting a consistently rich exhaust, though this is less common for a "circuit high voltage" code.
Vehicle-specific pages to check next
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