O2 Sensor Circuit High Voltage (Bank 2 Sensor 2)
P0158 indicates that the oxygen sensor (HO2S) on Bank 2, Sensor 2 (downstream of the catalytic converter) is reporting a voltage signal that is consistently above the normal operating range (typically >1.0V). This sensor monitors the oxygen content in the exhaust after the catalytic converter to assess converter efficiency. A high voltage reading suggests a rich air-fuel mixture, a faulty sensor, or a wiring issue. Common causes include a defective oxygen sensor, a short to voltage in the sensor circuit, a leaking fuel injector, or a malfunctioning catalytic converter. This code can lead to poor fuel economy, increased emissions, and potential damage to the catalytic converter if left unresolved.
01. Most Common Causes
- Faulty oxygen sensor (Bank 2 Sensor 2)
- Short to voltage in the sensor wiring or connector
- Engine running rich (e.g., leaking fuel injector, faulty fuel pressure regulator)
- Exhaust leak upstream of the sensor
- Faulty PCM (rare)
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Poor fuel economy
- Failed emissions test
- Possible rough idle or hesitation
03. Step-by-Step Diagnosis
Step 1: Scan for codes and record freeze frame data.
Step 2: Visually inspect the O2 sensor wiring and connector for damage, corrosion, or shorts.
Step 3: Using a multimeter, check the sensor signal voltage at idle and compare to specifications (should fluctuate between 0.1-0.9V).
Step 4: If voltage is stuck high (>1.0V), disconnect the sensor and check for reference voltage (typically 0.45V) from PCM.
Step 5: If reference voltage is present, replace the O2 sensor. If not, repair wiring or check PCM.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
You can drive short distances, but it may cause poor fuel economy and increased emissions. Prolonged driving could damage the catalytic converter.
How much does it cost to fix?▼
Replacing the oxygen sensor typically costs $150-$300 including parts and labor. Additional repairs for wiring or fuel system issues may increase the cost.