Parts for your 2015 Subaru Impreza-Ignition leads

2015 Subaru Impreza ignition leads: are they used, and what to service instead

For the 2015 Subaru Impreza (GJ/GP series), traditional ignition leads aren’t fitted or required. Technical documentation backs this up: the Subaru Service Manual for MY2015 Impreza (GJ/GP) lists a “direct ignition” setup using an ignition coil with a built‑in igniter on each cylinder, and the official Subaru parts catalogue shows individual coil-on-plug units but no high‑tension leads. Major plug and ignition catalogues for the FB-series engines (FB20 2.0L and FB16 1.6L) also specify coil-on-plug components and iridium spark plugs, with no listing for leads.

What does that mean under the bonnet? Instead of a single coil feeding spark through long leads to each plug, the Impreza’s FB engine parks a slim “pencil” ignition coil directly on top of each spark plug. The rubber boot on each coil provides insulation and sealing, so there’s no separate lead to replace. This design improves spark accuracy, reduces electrical losses, and trims maintenance.

For owners searching “ignition leads” for a 2015 Impreza, any results are a catalogue mismatch. The equivalent service items are the spark plugs and the four individual ignition coils (plus their boots). During servicing, focus on:

• Spark plugs: Subaru specifies long‑life iridium plugs, the interval is typically around 100,000 km in AU/NZ conditions. Always follow the owner’s manual or service schedule for exact timing.
• Ignition coils and boots: Inspect for cracking, heat hardening, or oil contamination in the plug tubes (a leaking rocker cover/tube seal can cause that). A failing coil often shows up as a misfire, rough idle, hesitation, or a check engine light with misfire or coil circuit codes.
• Good practices: Keep dirt out of the plug tubes, gently twist coils to release before removal, refit with clean boots, and torque plugs to the factory spec listed in the Subaru service manual. A tiny smear of dielectric grease on the inside of the boot can help future removal.

If a parts listing claims to be “ignition leads” for a 2015 Impreza, it’s not applicable to this model. What they actually need is the correct set of iridium plugs and, if required, replacement coil-on-plug units.

FAQs

Does a 2015 Subaru Impreza have ignition leads?
No. The 2015 Impreza uses a direct, coil‑on‑plug ignition system. Subaru’s MY2015 GJ/GP service manual and parts catalogue show individual coils per cylinder and no separate high‑tension leads.

What should be serviced instead of ignition leads on a 2015 Impreza?
Replace the iridium spark plugs at the scheduled interval and inspect each coil-on-plug unit and its boot. Check for oil in the plug tubes, cracked boots, or weak coils if there’s a misfire.

What are signs the coils or plugs need attention?
Rough idle, hesitation on acceleration, increased fuel use, and a check engine light. Common fault codes include P0301–P0304 (misfires) and P0351–P0354 (coil circuit). Address plugs first if they’re due, swap coils between cylinders to confirm a suspect unit.