Parts for your 2017 Subaru Forester-Ignition leads

2017 Subaru Forester ignition leads

The 2017 Subaru Forester doesn’t use traditional ignition leads (spark plug wires). Both engines offered that year—the FB25 2.5‑litre four and the FA20F 2.0‑litre turbo—run coil‑on‑plug (COP) ignition, where an individual ignition coil sits directly on top of each spark plug. This is shown in the 2017MY Subaru Forester service manual’s ignition system diagrams, the Subaru genuine parts catalogue (which lists individual coil assemblies and no high‑tension cords), and major application catalogues from NGK and Denso that specify COP coils for these engines. If a parts search turns up “ignition leads” for this model, it’s almost certainly a catalogue mismatch.

Why no leads? COP shortens the high‑voltage path, improving spark energy and timing accuracy while reducing electrical losses and radio interference. It’s also more reliable in wet conditions—handy for life in Aotearoa New Zealand and Australia—and lets the engine control unit monitor and manage each cylinder precisely for emissions and fuel economy. Packaging is tidier on Subaru’s flat‑four, with less clutter over the rocker covers.

For servicing, owners should focus on what the Forester actually has: spark plugs and individual coils/boots. Follow the factory service schedule in the owner’s manual for plug replacement intervals, and use the specified iridium plugs. When the plugs are out, it’s smart to inspect the coil boots for cracking, carbon tracking, or oil contamination from a rocker cover gasket weep. A dab of silicone dielectric grease on the inside of the boot can help future removal and seal out moisture. If there’s a misfire, rough idle, or a flashing check‑engine light with a cylinder‑specific code, test the suspect coil and replace it as needed—there’s no set replacement interval for coils, just condition‑based service.

• Replace spark plugs at the scheduled kilometre interval with the exact spec listed by Subaru.
• Inspect coil boots and plug wells for moisture or oil, clean and dry before refitting.
• Seat and torque coils correctly, avoid pulling on connectors or wiring.

Does a 2017 Subaru Forester have ignition leads?
No. The 2017 Forester’s FB25 and FA20F engines use coil‑on‑plug ignition, with one coil mounted directly to each spark plug, so there are no external high‑tension leads. This configuration is documented in the Subaru service manual and genuine parts catalogue, and reflected in NGK/Denso application listings.

What should be serviced instead of ignition leads on a 2017 Forester?
Service the spark plugs at the interval in the owner’s manual and inspect the individual coils and boots whenever the plugs are changed. Look for cracking, tracking, or oil in the plug tubes. Coils are replaced only if faulty, typically indicated by misfire codes or a rough idle.

Can aftermarket ignition leads be fitted to the 2017 Forester?
No. There’s nowhere to fit them—each cylinder has a dedicated coil sitting on the plug. Converting to a remote‑coil/lead setup would be impractical and offers no benefit over the factory COP system. Stick with OEM‑spec coils and the correct iridium plugs for best results.