P0158: O2 Sensor Circuit High Voltage (Bank 2, Sensor 2)
Key takeaways
- P0158 means the downstream oxygen sensor on bank 2, after the catalytic converter, is reporting a voltage that stays too high.
- The car is usually safe to drive; the downstream sensor has little say over fueling on most cars, but a real rich condition needs attention.
- Wiring and connector faults are the first suspect; a new downstream sensor is $150–$400 and a wiring repair $100–$250.
- 42 manufacturer bulletins from 12 makes name P0158, many of them engine-computer updates or dedicated P0158 bulletins for Jeep and Ram.
What P0158 means
The oxygen sensor behind your catalytic converter, on one side of the engine, is reporting a voltage that’s too high for too long.
The scanner name is O2 Sensor Circuit High Voltage (Bank 2, Sensor 2). Bank 2 is the side of a V engine without cylinder 1, so this code only appears on V6, V8 and flat engines. Sensor 2 is the downstream sensor, after the converter; its main job is to tell the engine computer whether the converter is working. A normal downstream sensor holds fairly steady somewhere under about 0.9 volts. High voltage means “rich,” lots of fuel and no oxygen. The computer sets P0158 when the reading stays above its limit, often after a deceleration when the sensor should drop low.
Is it safe to drive?
Usually yes. The downstream sensor has little say over fueling on most cars, so the engine drives the same. The car will fail an OBD emissions inspection, and some cars show slightly worse fuel economy.
What changes the answer: a rough-running engine, a strong fuel smell, black smoke, or a flashing check engine light. Those mean the engine really is running rich or misfiring, and unburned fuel can overheat the catalytic converter. Get that checked soon.
Causes, ranked
| Cause | How you confirm it | Typical cost (US independent shop, 2026) |
|---|---|---|
| Wiring or connector fault (signal shorted to the heater or power wire, water or corrosion in the plug) | Wiring melted near the exhaust, green corrosion in the plug; voltage reads high with the sensor unplugged | $100–$250 |
| Engine computer software (several makes) | A bulletin for your exact model and year names P0158 | $100–$200, often $0 under warranty |
| Blown fuse or shorted heater circuit feeding voltage into the signal | Fuse check; heater code P0161 sets too | $0–$20 fuse; wiring as above |
| Downstream O2 sensor failed or contaminated | Live data stuck high while the engine isn’t rich; sensor tip coated with coolant or oil residue | $150–$400 |
| Engine actually running rich on bank 2 (leaking injector, faulty upstream sensor) | Upstream sensor and bank 2 fuel trims also show rich; fuel smell; P0175 | Upstream sensor $150–$400; injector $250–$600 |
What to check first
- Read all the codes. Heater codes point to the fuse and wiring. Rich or misfire codes come first; fix those and the downstream reading may settle.
- Check the O2 heater fuse. A blown fuse means a short somewhere, so find it before replacing the fuse.
- Inspect the harness under the car. Look for wires touching the exhaust, a melted clip, or water in the connector. Unplug it, dry it, and look for green corrosion.
- Watch live data. A shop compares upstream and downstream sensors and fuel trims on both banks. If bank 2 looks rich across the board, the sensor is telling the truth.
- Check bulletins before buying parts. This code has a lot of them. Stellantis has engine-computer updates for 2021–2024 Jeep Wrangler and Gladiator and dedicated “O2 sensor 2/2 circuit high” bulletins for 2019–2021 Ram 1500 and 2019–2020 Wrangler. Nissan and Infiniti have bulletins for the 2018 Armada, Titan and QX80, Ford for the 2014–2015 Explorer and Taurus 3.5L and 3.7L and water in the connectors on 2020 Super Duty 6.2L and 7.3L trucks, and Toyota for 2005–2010 Camry, Avalon, RAV4, Highlander, Sienna and Venza, where the upstream air-fuel sensor’s response is the cause.
- Replace the sensor last, once wiring, software and fueling check out. Clear the code and drive a normal mixed trip to confirm.
What it costs
The cheap outcome is a fuse or a cleaned and resealed connector, under $20 in parts. The common outcome is a wiring repair at $100–$250, a software update at $100–$200, or a downstream sensor at $150–$400 installed. The expensive outcome is fixing a real rich condition upstream, such as a leaking injector at $250–$600. Paying for a look at live data first is what keeps you from buying a sensor that was reporting the truth. Our O2 sensor check engine light guide covers the whole sensor family.
Related codes
P0158 often appears with P0138, the same test on bank 1; Nissan, Ford and Toyota bulletins name the two together. P0161 is the heater for this sensor and P0157 the low-voltage code. If P0430 shows up later, the converter test may be reading bad data from this sensor, so fix P0158 first. If the car feels fine otherwise, see check engine light on but car runs fine.
What owners report to NHTSA
1 complaints filed with NHTSA mention P0158, 1 of them since 2015, across 1 different models. The component owners most often filed it under: electrical system:instrument panel:speedometer/odometer.
Manufacturer service bulletins that name P0158
42 technical service bulletins and manufacturer communications filed with NHTSA mention P0158, from 12 makes. A bulletin means the manufacturer has documented a known cause or a fix procedure for that model. Examples:
- JEEP GLADIATOR (2024), bulletin 11001133: "Flash: Powertrain Control Module (PCM) Updates Customers must experience a Malfunction Indicator Lamp (MIL) illumination and the vehicle must exhibit/set one or more of the following Diagnostic Trouble Codes (DTCs): P11…
- JEEP WRANGLER (2024), bulletin 11001282: "Flash: Powertrain Control Module (PCM) Updates Customers must experience a Malfunction Indicator Lamp (MIL) illumination and the vehicle must exhibit/set one or more of the following Diagnostic Trouble Codes (DTCs): P11…
- RAM 1500 (2019, 2020, 2021), bulletin 10187084: CEL Check Engine Lamp On, DTC P0158 O2 Sensor 2/2 Circuit High
- FORD F-650 SD (2020), bulletin 10181940: Some 2020 F-Super Duty vehicles equipped with the 6.2L or 7.3L engine built on or before 05-Jun-2020 may exhibit an illuminated malfunction indicator lamp (MIL) with diagnostic trouble codes (DTCs) P0132, P0135, P0138, P…
- FORD F-250 SD (2020), bulletin 10199477: Some 2020 F-Super Duty vehicles equipped with a 6.2L or 7.3L engine, 10R140 transmission, and built on or before 05-Jun-2020 may exhibit an illuminated malfunction indicator lamp (MIL) with diagnostic trouble codes (DTCs…
- INFINITI QX80 (2018), bulletin 10145544: 2018 QX80; MIL ON WITH DTC P0138 AND/OR P0158 IF YOU CONFIRM The MIL is ON with one or both of the following DTCs: - P0138 (Heated oxygen sensor heater 2 [bank 1] circuit high voltage) - P0158 (Heated oxygen sensor heate…
Sources: NHTSA Office of Defects Investigation complaint database and manufacturer communications file, snapshots September 2026. A complaint or bulletin that mentions a code is a report about that vehicle, not a statement that the code has one cause.
Frequently asked questions
Can I drive with P0158?
Usually yes. The downstream sensor mostly checks the converter, so the engine drives the same. Get it looked at soon if you smell fuel, see black smoke or the engine runs rough, since those mean it really is running rich.
Is P0158 a bad catalytic converter?
No. A worn converter sets P0430 on bank 2, and it usually makes the downstream sensor switch too much, not stay high. P0158 points to the sensor, its wiring, software, or an engine running rich.
Why did P0158 come back after I replaced the sensor?
Most often the fault was in the wiring: a signal wire shorted to the heater or power wire, or water in the connector. Check for a bulletin too, since several makes fix this code with an engine-computer update.
Can P0158 damage the catalytic converter?
The sensor fault itself won't. But if the high reading is real and the engine runs rich for months, extra fuel can overheat and damage the converter.