OBD-II code · Powertrain (generic, extended)

P21FD Fuel Control System B Too Rich at Higher Load (Bank 1)

Fuel Control System B Too Rich at Higher Load (Bank 1): the fuel-trim control is correcting for an over-rich mixture in this operating range.

Is it safe to drive with P21FD?

Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.

Common causes

  • Most likelyFuel pressure regulator stuck high

Symptoms

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

Repair at a glance

Difficulty
Medium
DIY friendly
Often, with basic tools
Typical labour
0.7–5 h
Emissions test
Likely to fail
Parts involved
Fuel Injector, Fuel Pressure Regulator

Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.