O2 Sensor Circuit High Voltage Bank 1 Sensor 4
Bank 1 sensor 4 O2 sensor signal voltage above expected range — short to power or sensor stuck high. A drifted or sluggish lambda sensor lets the mixture run lean or rich without correction — fuel economy and emissions suffer immediately.
Affected components
- Oxygen sensor b1s4
- Sensor wiring
Common causes
- High likelihood: Signal wire shorted to battery
- Low likelihood: Connector pins corroded - high contact resistance
- Low likelihood: Supply wire pinched against B+ source
Possible symptoms
- Check engine light on
- Increased fuel consumption
- Possible rough idle or hesitation
- Failed emissions test
Diagnostic notes
- The malfunction indicator lamp may illuminate
- This code can affect emissions
- A drive cycle may be required after repair
Sources
Diagnostic information is provided for reference only. Confirm the code with a compatible scan tool and follow the vehicle manufacturer's service procedures before replacing components.