Diagnostic article Generic OBD-II
P21E3: High injector current with cylinder 4 and channel 2 names kept separate
Understand P21E3’s active-stage criterion and the mapping needed before applying it to a physical injector.
Read before applying this article
Documented application
2025 GM 25OBDG07A Part 2 monitor tables only; model, engine and transmission applicability are not established by the unresolved application-matrix filename join.
The code alone does not identify a failed part or establish that a vehicle is safe to drive. Confirm the vehicle, reporting module and applicable service procedure.
The generic P21E3 designation is cylinder 4 injector B circuit high. GM's corresponding row is labeled injector 2. That difference is an unresolved channel-to-cylinder mapping, not enough evidence to decide that one source's numbering is wrong.
The supported active-current check
The row describes a short-to-supply electrical fault using output current above 3.8 A while the power stage is active. It lists three events for maturation, a minimum engine speed of 80 rpm and a supply-voltage window. The continuation on the next page adds the referenced inhibition information.
The stage state distinguishes this monitor from the associated open-load and low-circuit checks, which use inactive-stage voltage. An off-state current observation cannot reproduce the P21E3 criterion.
Establish identity before drawing a component conclusion
A full code readout, controller identification and calibration information are needed to choose the correct vehicle wiring diagram. Acting on either cylinder 4 or channel 2 as an assumed physical location risks investigating the wrong injector circuit.
Once identity is resolved, preserve the active-stage current and diagnostic category. The code does not measure fuel spray or establish that the injector's mechanical portion is defective. It also cannot separate a wiring fault, electrical load problem and internal driver cause by itself. The documented threshold is a monitor parameter, not a safe external energization instruction or an automatic replacement decision.
Source and scope
2025 GM 25OBDG07A Part 2 monitor tables only; model, engine and transmission applicability are not established by the unresolved application-matrix filename join. These are documented monitor criteria, not a universal repair procedure. GM PDF, physical page 555 · GM PDF, physical page 556.
Article source documents
Source checks describe how the text was prepared; they do not certify a diagnosis or confirm compatibility with every vehicle using this code.
Original code reference
Dictionary definition
Cylinder 4 Injector B Circuit High
This definition retains its original catalog scope. The article above is limited to its explicitly documented application.
Reference scope
Generic OBD-II definition.
A manufacturer label does not establish the model, year, engine or module to which a diagnosis applies. Read the safety and diagnostic limits.
Definition source
- DTC Database: pinned community code definitions
Source checked · MIT