P2BF1: Fuel Control System B Too Rich Bank 1

What it means

Fuel control system B on bank 1 is reporting a rich condition. This indicates the system is correcting for a mixture that is richer than its calibrated range.

At a glance

• Usually lights the check-engine light
• Affects emissions; the car can fail an emissions test

How it works

Fuel control system B adjusts the air-fuel mixture for engine bank 1, the bank containing cylinder 1. The engine control module uses oxygen-sensor feedback and fuel-trim data to detect when bank 1 is receiving too much fuel for the measured air. This code sets when system B's correction indicates that bank 1 is richer than the calibrated range.

Common causes

Most likely first.

1. Fuel rail pressure high or regulator stuck
2. Injector leaking - over-fuelling

Symptoms

• Check engine light on
• Increased fuel consumption
• Black smoke from exhaust on acceleration
• Smell of unburned fuel, fouled spark plugs

How to diagnose it

1. Save freeze-frame data and compare bank 1 live fuel trims and oxygen-sensor readings with bank 2 to determine whether the rich correction is confined to bank 1.
2. Inspect for fuel leakage around bank 1 injectors and note any black smoke or strong fuel smell.
3. Measure fuel rail pressure against the manufacturer's specification and check the regulator if pressure is elevated.
4. If bank 1 alone is rich, test its injectors for leakage and inspect their wiring and control.
5. Check the bank 1 oxygen-sensor circuit and air-measurement data before replacing parts, since faulty feedback can imitate a rich mixture.

Common fixes

• Repair a fuel pressure regulator fault if testing confirms excessive rail pressure.
• Replace a leaking bank 1 injector after confirming it is over-fuelling.
• Repair damaged injector wiring or connections on bank 1.
• Replace a bank 1 oxygen sensor only if its circuit and response tests show it is faulty.

Can I keep driving?

Avoid unnecessary driving, especially under acceleration, if there is black smoke, a strong fuel smell, or rough running; stop if fuel is visibly leaking. Excess fuel can foul spark plugs and damage the catalytic converter.