Powertrain
generic / SAE
P01F6
O2 Sensor Signal Biased/Stuck Lean Bank 1 Sensor 4
Bank 1 sensor 4 O2 sensor signal is biased low — sensor stuck reading lean regardless of true mixture. A drifted or sluggish lambda sensor lets the mixture run lean or rich without correction — fuel economy and emissions suffer immediately.
SystemPowertrain
Typegeneric / SAE
GroupP0
Range / number1 / F6
Possible causes
- Sensor aged or contaminated high
Symptoms
- Check engine light on
- Increased fuel consumption
- Possible rough idle or hesitation
- Failed emissions test
Inspection / repair
- Difficulty: medium
- DIY: possible
- Estimated cost: 80–400 €
- Estimated time: 0.5–2 h
- Component: oxygen sensor b1s4
- MIL / check engine light
- emissions-relevant
- drive cycle required
Sources
References
sae:J2012