Subaru 2.5 EJ25 Firing Order Diagram

Reading the 2.5L EJ25 Boxer-Four diagram correctly

Passenger/right side carries cylinders 1 and 3; driver/left side carries 2 and 4, with the lower-numbered cylinder on each bank nearest the front/timing-belt end. Read the vehicle as installed and use the manufacturer's left/right convention, not the side from which you happen to be standing. The first cylinder listed in 1-3-2-4 begins the sequence but does not define a universal connector position.

Subaru factory service specifications list 1-3-2-4, and the horizontally opposed layout means a conventional inline-four drawing is actively misleading. The two cylinders on each bank lie opposite the other bank rather than in one front-to-rear row. A wasted-spark coil pack can fire paired plugs simultaneously, but that electrical pairing is not the four-event combustion order. Trace tower labels or individual coil connectors from the exact wiring diagram before swapping leads. On coil-on-plug engines, use the diagram for cylinder identity and diagnosis; the PCM, not a physical distributor cap, schedules spark.

Which 2.5L EJ25 Boxer-Four firing order applies?

Subaru factory service specifications list 1-3-2-4, and the horizontally opposed layout means a conventional inline-four drawing is actively misleading. The two cylinders on each bank lie opposite the other bank rather than in one front-to-rear row. This distinction matters because the engine can look nearly identical from above. Treat the camshaft or engine assembly as the authority when parts have been mixed. A firing order cast into an intake, copied from a generic decal, or remembered from another V8 is not enough to identify a modified engine.

The application table separates the order, cylinder banks, and ignition-system notes. Read all columns before routing. The first number in 1-3-2-4 is cylinder 1, but the physical No. 1 terminal can appear in different clock positions when a distributor has been installed on a different gear tooth.

Bank numbering and verification on the 2.5L EJ25 Boxer-Four

A wasted-spark coil pack can fire paired plugs simultaneously, but that electrical pairing is not the four-event combustion order. Trace tower labels or individual coil connectors from the exact wiring diagram before swapping leads.

Subaru factory service specifications list 1-3-2-4, and the horizontally opposed layout means a conventional inline-four drawing is actively misleading. The two cylinders on each bank lie opposite the other bank rather than in one front-to-rear row.

Procedures used with this specification

These steps are the same for every vehicle in this family, so they are documented once rather than repeated on each page. The values above remain specific to this Subaru 2.5L EJ25 Boxer-Four.