P2BF3: Fuel Control System B Too Rich Bank 2

What it means

Fuel control system B on bank 2 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 2, the bank opposite the one containing cylinder 1. The engine control module uses oxygen-sensor feedback and fuel-trim data to detect when bank 2 is receiving too much fuel for the measured air. This code sets when system B's correction indicates that bank 2 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 2 live fuel trims and oxygen-sensor readings with bank 1 to determine whether the rich correction is confined to bank 2.
2. Inspect around bank 2 injectors for fuel leakage 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 2 alone is rich, test its injectors for leakage and inspect their wiring and control.
5. Check the bank 2 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 2 injector after confirming it is over-fuelling.
• Repair damaged injector wiring or connections on bank 2.
• Replace a bank 2 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.