P0152
O2 Sensor Circuit High Voltage (Bank 2 Sensor 1)P0152 is a generic OBD-II powertrain diagnostic trouble code: O2 Sensor Circuit High Voltage (Bank 2 Sensor 1). It is logged by the engine control unit when the o2/lambda monitor detects that a specific fault threshold has been exceeded — typically resulting in the malfunction-indicator lamp (MIL / check-engine light) being illuminated.
What P0152 means
P0152 is stored when the Engine Control Module (ECM) detects that the upstream oxygen sensor on Bank 2, Sensor 1 (B2S1) has produced a sustained high-voltage output — typically above 1.0–1.2 V — for longer than a manufacturer-defined threshold. Under normal operation a conventional zirconia O2 sensor oscillates between approximately 0.1 V (lean) and 0.9 V (rich), so a signal held above that range tells the ECM the sensor is either reporting an abnormally rich exhaust condition or has developed a voltage bias fault.
When the ECM receives a persistently high voltage from B2S1, it interprets this as a very rich air-fuel mixture and commands a fuel cut on the Bank 2 side (negative fuel trim) to compensate. If the voltage is caused by a genuine rich condition (stuck-open injector, excessive fuel pressure, failed mass airflow sensor), the engine may run noticeably rich, producing black smoke, fouled spark plugs, and poor fuel economy. However, the code is also commonly caused by a wiring fault — specifically the sensor's signal wire shorting to the 12 V heater supply wire — which forces the ECM to read the heater voltage as sensor output without any genuine richness in the exhaust.
The Bank 2 upstream sensor is part of the primary closed-loop fuel management system, so a high-voltage fault that causes the ECM to cut too much fuel can result in a lean misfire, rough idle, or hesitation under load. This makes P0152 moderately more significant than downstream sensor codes. Accurate diagnosis requires monitoring the live voltage reading while disconnecting the sensor: if the voltage drops to zero when the sensor is unplugged, the fault is in the wiring (short to power); if the scan tool still reads high voltage, the ECM input circuit may be compromised.
Typical repairs include correcting a wiring short between the heater and signal circuits, replacing a failed oxygen sensor with a biased internal element, or addressing the underlying rich fuel condition causing the elevated exhaust oxygen depletion. Companion codes such as P0172 (System Too Rich Bank 2) often appear alongside P0152.
Common causes
Most-frequently reported root causes when P0152 is logged.
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1
Signal wire shorted to the heater supply (12 V) wire inside the harness or at the connector
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2
Failed O2 sensor with an internally shorted or biased element producing artificially high voltage
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3
Rich air-fuel mixture on Bank 2 (stuck-open fuel injector, high fuel pressure)
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4
Faulty MAF or MAP sensor causing the ECM to over-fuell Bank 2
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5
Damaged wiring insulation allowing signal wire contact with a voltage source
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6
Oil or coolant contamination of the sensor element causing signal bias
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7
Corroded connector pins creating a voltage leak path
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8
Faulty ECM/PCM output driver (rare)
Symptoms drivers notice
How to diagnose P0152
A typical diagnostic flow when this code is present.
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1
Retrieve all stored DTCs with a scan tool; note companion codes (P0172, misfire codes on Bank 2) that suggest a genuine rich condition versus an isolated circuit fault.
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2
Monitor B2S1 live voltage on the scan tool with the engine at operating temperature; a healthy upstream sensor should switch between ~0.1 V and ~0.9 V. A signal stuck above 1.0 V confirms the fault.
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3
Unplug the B2S1 connector with the engine running and observe the scan tool reading: if it drops to 0 V the fault is in the sensor or its wiring; if it remains elevated, suspect an ECM input circuit issue.
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4
Inspect the entire sensor harness for any location where the signal wire (typically grey or white) runs alongside or contacts the heater supply wire (typically white); check for melted insulation or chafed sections near exhaust heat shields.
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5
Measure heater-circuit voltage on the supply wire at the connector; confirm it is ~12 V and verify it is not present on the signal wire pin.
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6
Check short-term and long-term fuel trims for Bank 2; large negative LTFT (more negative than −10%) indicates the ECM is trying to lean out Bank 2, which may point to a genuine rich condition to investigate (injectors, fuel pressure regulator, EVAP purge valve).
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7
Replace the sensor if wiring inspects clean and no rich fuel cause is found; clear codes and drive through a full warm-up cycle to verify resolution.
Related powertrain codes
- P0040 — Upstream Oxygen Sensors Swapped From Bank To Bank
- P0041 — Downstream Oxygen Sensors Swapped From Bank To Bank
- P0130 — O2 Sensor Circuit Malfunction (Bank 1 Sensor 1)
- P0131 — O2 Sensor Circuit Low Voltage (Bank 1 Sensor I)
- P0132 — O2 Sensor Circuit High Voltage (Bank 1 Sensor 1)
- P0133 — O2 Sensor Circuit Slow Response (Bank 1 Sensor 1)
Frequently asked questions
Can P0152 cause the engine to run lean instead of rich?
Yes. If the ECM receives a high-voltage signal it commands a large negative fuel trim correction. If that correction overshoots — or if the high voltage was caused by a wiring fault rather than a real rich condition — the engine can end up running lean, causing hesitation and potential misfires.
How do I tell if P0152 is a wiring problem or a sensor problem?
Unplug the sensor while the engine is running and watch the scanner's live voltage for B2S1. If the reading immediately drops to 0 V (or below 0.1 V), the sensor or its internal element is at fault. If the reading remains high after unplugging, the wiring between the sensor and ECM is the likely cause.
Will P0152 damage the catalytic converter?
A sustained rich condition can overheat and melt the catalytic substrate over time. If P0152 is accompanied by P0172 and the engine is genuinely running rich, repair promptly to avoid converter damage. A wiring-only fault with no real richness poses much less risk.
Is P0152 the same as P0132?
They describe the same fault type — O2 Sensor Circuit High Voltage — but on different banks. P0132 is for Bank 1 Sensor 1; P0152 is for Bank 2 Sensor 1. Diagnosis steps are identical; only the sensor location differs.
Disabling P0152 in software
RaceTune can permanently disable P0152 — and any other OBD-II diagnostic trouble code — on every ECU family we support. The monitor is disabled inside the ECU itself, so the fault stops being logged: the warning light stays off and the engine never enters limp mode for this code. The change is tied to your exact software version.
Software modifications affect emissions compliance and are not road-legal in many jurisdictions. RaceTune service files are intended for motorsport, off-road, and export use.
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