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.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: medium
Symptoms
- Check engine light on
- Increased fuel consumption
- Black smoke from exhaust on acceleration
- Smell of unburned fuel, fouled spark plugs
Common causes
Ordered by how often each turns out to be the cause.
- Fuel pressure regulator stuck highCommon
Parts involved
- Fuel Injector
- Fuel Pressure Regulator
P21FD is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.