Emissions

P0152 — O2 Sensor Circuit High Voltage (Bank 2 Sensor 1)

Severity: medium Drive with care, to a shop

What P0152 means

The engine computer monitors the upstream (pre-catalyst) oxygen sensor on bank 2. Its voltage normally swings rapidly as the mixture shifts between rich and lean. P0152 sets when the signal stays too high, which points to a very rich mixture, a failed sensor, or a short to voltage in its circuit.

Symptoms

  • Check engine light on
  • Worse fuel economy
  • Rough idle or hesitation
  • Higher emissions
  • Black smoke from the bank 2 side
  • Possible companion code P0175 (rich, bank 2)

Possible causes

  1. Failed bank 2 upstream O2 sensor
  2. Damaged wiring or connector, short to voltage
  3. Genuinely rich air-fuel mixture (injectors, fuel pressure)
  4. Exhaust leak near the sensor skewing readings
  5. ECM fault or software issue (rare)

How to diagnose

  1. Read codes and freeze frame data, note related codes such as P0175
  2. Confirm which side is bank 2 and locate the sensor for your engine
  3. Inspect the sensor, harness and connector for melting, chafing or corrosion
  4. Watch live sensor voltage and fuel trims (STFT/LTFT) with a scan tool
  5. Rule out a real rich condition: fuel pressure, leaking injectors, MAF sensor, air filter
  6. Check the exhaust near the sensor for leaks
  7. Test the signal circuit for a short to voltage and check heater resistance
  8. If all is good, verify ECM power and ground and look for software updates

Common fixes

  • Replace the bank 2 upstream O2 sensor
  • Repair the wiring or replace the connector
  • Fix the cause of the rich mixture: injectors, fuel pressure regulator, sensors
  • Repair the exhaust leak
  • Reflash or replace the ECM (last resort)

Questions and answers

What does P0152 mean?

The upstream oxygen sensor on bank 2 is reporting voltage that is too high. The cause may be the sensor, its wiring, or a rich mixture.

Can I drive with P0152?

For a short time, yes, but repair it soon. A rich mixture wastes fuel and can damage the catalytic converter.

Will replacing the sensor fix it?

Not always. Check the wiring, fuel trims and mixture first, or the new sensor may set the same code.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.