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P0152 — O2 Sensor Circuit High Voltage Bank 2 Sensor 1

Generic OBD-II · all makesPowertrain (engine & transmission)

P0152 indicates that the oxygen sensor (Bank 2, Sensor 1) is reporting a voltage signal that is consistently higher than the normal operating range (typically above 1.0 volt). This usually means the sensor is detecting a very rich air-fuel mixture or there is a fault in the sensor or its circuit.

Symptoms

What causes it — most likely first

1. Faulty oxygen sensor (Bank 2, Sensor 1)

The sensor itself is the most common failure. Internal short circuits or contamination (oil, coolant, fuel additives) can cause a permanently high voltage output.

2. Short to voltage in sensor wiring or connector

A short circuit between the oxygen sensor signal wire and a 12V source (e.g., damaged harness, melted insulation) can force the signal high.

3. Exhaust leak upstream of the sensor

An exhaust leak before the sensor allows outside oxygen to enter, which the sensor may misinterpret as a lean condition, but in some cases can cause erratic high voltage readings if the leak is near the sensor.

4. Rich fuel mixture (fuel system issue)

Excess fuel from a leaking injector, faulty fuel pressure regulator, or stuck-open purge valve can cause a rich mixture, driving the sensor voltage high.

5. Engine mechanical fault (e.g., low compression, misfire)

A misfire or mechanical issue can dump unburned fuel into the exhaust, causing a false rich reading. This is less common but possible.

6. PCM (engine computer) failure

A defective PCM is extremely rare for this code. It should only be considered after thoroughly checking all other possibilities, as misdiagnosis is common.

How it's diagnosed

  1. Connect a scan tool and verify the code is P0152. Check freeze frame data for conditions when the code set.
  2. Monitor the Bank 2 Sensor 1 voltage with the engine running. A steady high voltage (above 0.9V) indicates a rich condition or sensor fault. Compare to Bank 1 Sensor 1 for reference.
  3. Inspect the oxygen sensor wiring and connector for damage, corrosion, or shorts to battery voltage. Check for melted or chafed wires near the exhaust.
  4. Check for exhaust leaks upstream of the sensor (e.g., cracked manifold, loose gasket). A leak can introduce oxygen and skew readings.
  5. Test the fuel system: check fuel pressure, look for leaking injectors, and verify the purge valve operation. A rich mixture can cause high voltage.
  6. If all other checks pass, replace the Bank 2 Sensor 1 oxygen sensor with a quality part. Only consider PCM replacement as a last resort after professional diagnosis.

Code facts & related codes

SystemPowertrain (engine & transmission)
StandardizationSAE generic — identical on every make
Related codesP0150 — O2 Sensor Circuit Bank 2 Sensor 1P0151 — O2 Sensor Circuit Low Voltage Bank 2 SP0153 — O2 Sensor Circuit Slow Response Bank 2P0154 — O2 Sensor Circuit No Activity DetectedP0155 — O2 Sensor Heater Circuit Bank 2 SensorP0156 — O2 Sensor Circuit Bank 2 Sensor 2

Frequently asked

Can a bad PCM cause P0152?

Yes, but it is extremely rare. The vast majority of P0152 codes are caused by a faulty oxygen sensor, wiring issues, or a rich fuel mixture. Replacing the PCM without proper diagnosis is almost always a waste of money.

Will a P0152 code clear itself?

If the underlying problem is temporary (e.g., a one-time rich condition), the code may clear after several drive cycles with normal readings. However, if the fault is persistent, the code will return. It's best to diagnose and fix the root cause.

Is it safe to drive with a P0152 code?

You can usually drive short distances, but the engine may run rich, reducing fuel economy and potentially damaging the catalytic converter over time. It's recommended to address the issue promptly.

Can an exhaust leak cause P0152?

Yes, an exhaust leak upstream of the sensor can allow outside air to enter, which can cause the sensor to read lean or erratic. However, a high voltage code is more often caused by a rich condition or sensor fault. Still, inspect for leaks as part of diagnosis.