Emission controls · Powertrain · generic (SAE-defined)
P0158: O2 Sensor Circuit High Voltage (Bank 2 Sensor 2)
P0158 means the downstream oxygen sensor on bank 2, after the catalytic converter, is reading higher voltage than it should, from a stuck sensor, short to voltage or rich running.
Standard title per SAE J2012 / ISO 15031-6 · Updated 2026-11-07 · By CarWhere Research
How P0158 sets
The powertrain control module (PCM) monitors the bank 2 sensor 2 oxygen (O2) sensor and may briefly lean out the mixture to see the signal drop. If the reading stays above its plausible range for a calibrated time, the PCM sets P0158. Thresholds vary by manufacturer.
Common causes of P0158
Roughly most likely first; the actual cause depends on the vehicle and needs testing to confirm.
- Failed bank 2 sensor 2 oxygen sensor
- Signal wire shorted to a voltage source
- Rich condition on bank 2
- Sensor contamination from oil or fuel
- Corrosion in the connector
P0158 symptoms
- Check engine light on
- Usually no drivability symptoms
- Poor fuel economy if the engine is running rich
How P0158 is diagnosed
- Scan for codes; investigate any rich or misfire codes first.
- Inspect the downstream harness for heat damage or fused wires.
- On live data, create a lean condition and confirm the reading falls.
- Check the signal wire for voltage with the sensor disconnected.
- Review bank 2 fuel trims for evidence of a real rich mixture.
Typical fixes for P0158
- Replace the bank 2 sensor 2 oxygen sensor
- Repair a short to voltage in the wiring
- Correct a rich-running fault on bank 2
Replace parts only after testing confirms the cause — a code names the circuit or condition that failed a check, not necessarily the faulty part. We don’t publish per-repair prices; for what households actually spend on upkeep, see car repair costs.
Related codes & warning lights
P0158 FAQ
What does code P0158 mean?
P0158 means the downstream oxygen sensor on bank 2, after the catalytic converter, is reading higher voltage than it should, from a stuck sensor, short to voltage or rich running. The standard definition is "O2 Sensor Circuit High Voltage (Bank 2 Sensor 2)."
Can I drive with a P0158 code?
Usually yes. The car generally runs normally, but if bank 2 is genuinely rich the catalytic converter can be stressed over time, so do not delay the diagnosis too long.
What is the difference between P0138 and P0158?
Both describe a high downstream sensor signal. P0138 is on bank 1, the side with cylinder 1, and P0158 is on bank 2.
Can P0158 come back after replacing the sensor?
Yes, if the real cause is a wiring short or a rich-running engine. Confirm the circuit and fuel trims are normal before or after the replacement.
Keep researching
More emission controls codes
Sources
- SAE J2012 — Diagnostic Trouble Code Definitions (standard code titles)
- ISO 15031-6 — Road vehicles: communication between vehicle and external equipment for emissions-related diagnostics, Part 6: Diagnostic trouble code definitions
- U.S. EPA — Vehicle Emissions Inspection and Maintenance (I/M) programs
- U.S. EPA, 40 CFR 86.1806-17 — Federal onboard diagnostics requirements for light-duty vehicles
- California Air Resources Board — On-Board Diagnostic (OBD) Program
General information written by CarWhere Research, not a diagnosis of your vehicle. Manufacturers can add their own sub-definitions and test conditions; confirm with the factory service information for your year, make and model. Before paying for a repair, check NHTSA for open recalls and your warranty booklet: federal law requires an emissions warranty on major emission-control parts such as the catalytic converter and engine computer.