What does code P21D9 mean?

Q: What does code P21D9 mean?

Cylinder 11 Injector B Circuit/Open. P21D9 is a generic powertrain code indicating that the engine control module (ECM) has detected an open circuit or excessive resistance in the electrical path for cylinder 11's 'B' fuel injector circuit. The ECM monitors the injector driver circuit and sets this code when the expected current flow is absent or out of range, meaning the injector may not be firing at all.

DTC codes / P21xx · Fuel and air metering / P21D9

P21D9Cylinder 11 Injector B Circuit/Open

P21D9 is a generic powertrain code indicating that the engine control module (ECM) has detected an open circuit or excessive resistance in the electrical path for cylinder 11's 'B' fuel injector circuit. The ECM monitors the injector driver circuit and sets this code when the expected current flow is absent or out of range, meaning the injector may not be firing at all.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaFuel and air metering

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.