What it means
The control module detected an open or otherwise faulty electrical circuit for cylinder 2 injector B. The code identifies the circuit fault; it does not establish what injector B refers to on a particular engine.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The engine controller operates injector B on cylinder 2 and monitors the injector's electrical circuit for the expected response. P21D0 sets when the cylinder 2 injector B circuit is detected as open or otherwise electrically faulty; injector B's exact identity can vary by engine.
Common causes
Most likely first.
- Open or damaged wiring
- Loose or corroded injector connector
- Injector electrical fault
Symptoms
- Check-engine light
- Rough idle or engine vibration
- Engine hesitation or reduced power
- Misfire, especially under load
How to diagnose it
- Save freeze-frame data and check cylinder-specific misfire data and related injector codes to identify when cylinder 2 began running unevenly.
- Use vehicle service information to locate cylinder 2 and injector B, then inspect its connector and harness for disconnection, corrosion, chafing, or heat damage.
- Check that the cylinder 2 injector B connector is seated and its terminals are not bent, spread, or pushed back.
- Use the wiring diagram to test the cylinder 2 injector B circuit for continuity and shorts following the manufacturer's procedure.
- Check the injector's electrical operation against the manufacturer's specification before condemning the injector.
Common fixes
- Reconnect and secure the cylinder 2 injector B connector.
- Repair an open or damaged wire in the cylinder 2 injector B circuit.
- Clean or repair corroded or damaged connector terminals.
- Replace cylinder 2 injector B if testing confirms an electrical fault.
Can I keep driving?
A rough-running or misfiring engine should not be driven under load because misfire can overheat and damage the catalytic converter. If the engine is smooth, limit driving and arrange repair of the cylinder 2 injector B circuit soon.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.