What does code P21DB mean?

Q: What does code P21DB mean?

Cylinder 1 Injector B Circuit Low. P21DB indicates that the powertrain control module (PCM) has detected an abnormally low voltage on the control circuit for cylinder 1 injector B, which is the second injector assigned to that cylinder in a multi-injector or staged injection system. The PCM monitors the circuit and sets this code when the voltage falls below the expected threshold, indicating a short to ground, an open circuit, or a faulty injector.

DTC codes / P21xx · Fuel and air metering / P21DB

P21DBCylinder 1 Injector B Circuit Low

P21DB indicates that the powertrain control module (PCM) has detected an abnormally low voltage on the control circuit for cylinder 1 injector B, which is the second injector assigned to that cylinder in a multi-injector or staged injection system. The PCM monitors the circuit and sets this code when the voltage falls below the expected threshold, indicating a short to ground, an open circuit, or a faulty injector.

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.