P21F7 code meaning
Fuel Control System B Too Rich Off Idle (Bank 2)
Powertrain system Generic code P21xx codes Check engine light
What P21F7 means
P21F7 sets when the second fuel path on bank 2 has to remove more fuel above idle than its rich limit permits. It needs an engine with two banks, separate front sensors and dual injection; inline engines such as Audi's 2.5 TFSI only have the bank 1 codes. No manufacturer publishes criteria for P21F7. An FCA patent for port plus direct injection engines explains the idea behind such split codes: a fault seen while only one path is fuelling is assigned to that path, whereas a fault during mixed operation goes to a general code such as P0175. When only this bank is affected, a leaking port injector on bank 2 or a bank 2 front sensor that reads rich is plausible; if both banks are rich, check what they share, such as pressure regulation. P2180 is the system A counterpart.
P21F7 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyMedium
- Typical labor0.5 to 3.5 hours
- Clears after repairAfter a drive cycle
Symptoms of P21F7
- Check engine lamp on
- Increased fuel consumption
Common causes of P21F7
- PossibleLeaking port injector on bank 2
- PossibleBank 2 front oxygen sensor reading rich
- Less likelyLow-pressure regulation too high (if bank 1 also rich)
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Fuel injectorOxygen sensor
What each part of P21F7 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| 1 | Area: fuel and air metering. |
| F7 | The exact fault in that area. |
What to do next
- Note P21F7 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P21F7
What does P21F7 mean?
P21F7 means "Fuel Control System B Too Rich Off Idle (Bank 2)". P21F7 sets when the second fuel path on bank 2 has to remove more fuel above idle than its rich limit permits. It is a generic code, so it means the same on every make.
Is it safe to drive with P21F7?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will P21F7 fail an emissions test?
Yes, it can. P21F7 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P21F7 to fix?
Difficulty: medium. A typical repair takes 0.5 to 3.5 hours of work. This is a job for a workshop.
Will P21F7 clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.