P0152 — Oxygen sensor circuit high voltage — bank 2, sensor 1

P0152 indicates signal voltage above the monitor limit for bank 2, sensor 1. This is the upstream sensor used for mixture control. This alone does not prove a rich mixture: a short circuit can influence the signal.

Affected system: Powertrain

Symptoms

• Engine warning lamp and a stored code.
• Higher fuel use or uneven running if mixture control is disturbed.

Possible causes

• Signal shorted to supply or the heater circuit.
• Damaged or contaminated sensor; an actual rich mixture requires separate confirmation.

What to check

• Confirm B2S1 in the engine diagram and save related codes and freeze-frame data before clearing anything.
• With the exhaust cold, inspect the B2S1 harness for melted insulation, rubbing, water in the connector and loose terminals.
• Compare the B2S1 signal with the OEM limit; check isolation from heater supply before attributing the reading to the mixture.
• Use the OEM procedure to separate sensor and harness faults; compare the signal with fuel trims and the other sensors. Identify whether this is a conventional or wideband sensor.
• After correcting the confirmed fault, repeat the OEM monitor conditions and check for code recurrence, beyond merely extinguishing the lamp.

Also written as: P0152-00, P015200, PO152 (some scan tools add the fault-type byte, e.g. -00).