Generic (OBD-II) interpretation in the TuningBot DTC database.
P · PowertrainFuelOBD2
What P21D1 means
P21D1
Cylinder 3 Injector B Circuit/Open
Generic · fuel
Data confidence65%
The control module detected an interruption (open circuit) in the Cylinder 3 Injector B circuit, so the expected electrical continuity was not present.
Symptoms
MIL illuminated
Possible rough running or misfire
Possible increased fuel consumption
Possible causes
Injector electrical or mechanical fault
Wiring or connector fault
Fuel supply fault
Air leak causing mixture deviation
Recommended checks
Read fuel trim / mixture adaptation values
Check injector circuits and compare cylinder balance
Powertrain: engine, transmission and driveline systems.
2
Generic SAE-standard code: same meaning on every make.
1D1
Specific fault index within the subsystem.
Frequently asked questions about P21D1
What does P21D1 mean?
Cylinder 3 Injector B Circuit/Open. The control module detected an interruption (open circuit) in the Cylinder 3 Injector B circuit, so the expected electrical continuity was not present.
Is P21D1 generic or manufacturer-specific?
P21D1 is a generic OBD-II code: it has the same meaning on every make and model that follows the SAE standard.
Can TuningBot remove P21D1 at file level?
If the fault logic lives in the ECU calibration, yes: our DTC Removal file service disables the specific fault entry and, where the ECU needs it, corrects the checksum too. Not sure whether your case qualifies? Request a free assessment and our engineers will check your ECU file.
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