2020 Subaru Outback 2.5L spark plug replacement.

Why it deserves attention.

Spark plugs ignite the mixture in each cylinder. Worn or damaged plugs can contribute to ignition problems, but a misfire may also involve a coil, wiring, fuel delivery, or another engine fault. Replacing plugs is not a substitute for diagnosing a warning light.

When should you check it?

Review the exact 2020 maintenance booklet, mileage, elapsed time, operating conditions, and replacement history before deciding the plugs are due. This lesson provides no universal interval. A flashing check-engine light or severe misfire calls for prompt assessment before further driving.

Get ready

What you need.

See the process

Watch the video.

The creator identifies a 2020 2.5L Outback and demonstrates access without lifting the engine. Battery removal begins at 0:36, driver-side work at 0:51, and passenger-side intake access at 8:53. Use the written 2020 specifications and battery safety checks alongside the demonstration.

Subaru Outback 2020 Spark Plugs Replacement · Fish by Shane

Preparation

Before you start.

• Let the engine become cold. Park on firm, level ground, select Park, set the parking brake, and switch the ignition off. Keep the key away from the vehicle while working.
• Read the complete lesson and watch the access demonstration first. The video removes the battery on the driver side and an intake hose on the passenger side. No engine lifting is included here.
• Before disconnecting the battery, review the owner manual settings and initialization instructions. Avoid sparks, flames, and jewelry near the battery. Support it upright when lifting; keep tools from bridging a terminal and bodywork.
• Photograph the coil connectors and intake connections before removal. Work one plug at a time and keep each coil identified. Stop if a connector lock, plug thread, or boot is damaged, or if you cannot reach the specified torque accurately.

The lesson

Step-by-step instructions.

1. 01

   Create driver-side access.

   Remove the battery following the battery safety instructions. Disconnect the ground cable at its battery-sensor connection first, supporting the sensor so it cannot rotate. Do not twist the sensor off its battery post. Unplug the sensor electrical connector. Release the positive-terminal holder, disconnect and isolate the positive cable, and release the cable holder and battery hold-down before lifting the battery out upright. Match the exposed coils to the video before proceeding.

2. 02

   Remove one ignition coil.

   Release its connector lock without pulling on the wires. Remove the coil retaining fastener and withdraw the coil carefully. If an access bracket is removed, note its orientation. Inspect the boot and well for oil, water, or tracking before exposing the spark-plug opening.

3. 03

   Remove the plug without side-loading it.

   Remove loose material around the well. Seat the spark-plug socket fully and keep it aligned with the plug as you loosen and withdraw it. Use short extensions as access requires. Do not force a plug that binds or leaves damaged threads; stop for assessment.

4. 04

   Start the new plug by hand and torque it.

   Confirm the replacement is correct and undamaged. Start it by hand with the socket and extension, keeping it straight. It must thread freely before any wrench is used. Tighten the new plug to the verified 2020 2.5L specification of 18 N·m (13.3 ft-lb). Do not use an impact tool or estimate tightness from reach alone.

5. 05

   Refit the coil and repeat on that side.

   Seat the coil boot onto its plug, restore the coil fastener, and tighten it to 8 N·m. Reconnect and check the connector lock. If the driver-side access bracket was removed, its verified fastener specification is 7.5 N·m. Complete the second plug with the same checks.

6. 06

   Make passenger-side access and replace the remaining plugs.

   Remove the original intake hose as shown in the demonstration without straining wiring or dropping debris into the intake. Keep the opening protected while it is disconnected. Replace the two plugs individually using the same hand-start, torque, coil, and connector checks. Restore the intake hose and secure its original retainers. The original intake-boot clamp specification is 3 N·m. If the air-cleaner case was removed, align its bottom claw; the front case fastener is 6 N·m and the case bracket fastener is 7.5 N·m.

7. 07

   Restore the battery and check the engine.

   Refit and secure the battery in its original position. Tighten its holder to 3.5 N·m. Restore the cable holder, sensor electrical connector, and positive-terminal holder. Restore the positive terminal at 6 N·m and its protective cover, then reconnect the ground cable to the battery sensor at 7.5 N·m while supporting the sensor against rotation. Check every coil connector, intake connection, and tool location. After reconnecting the ground cable, wait at least 10 seconds before switching the ignition on, then wait at least another 10 seconds with the ignition on before starting. Stop if the engine misfires or a warning persists.

Common mistakes to avoid.

• Buying plugs by model name alone, then fitting a turbo or earlier-engine plug.
• Cracking a ceramic insulator by levering a socket sideways in the limited space.
• Using the ratchet to force a plug that did not start freely by hand.
• Applying anti-seize to plated NGK plug threads or prying on a fine-wire electrode.
• Leaving a coil connector unlocked or an intake connection loose after gaining access.

Finish the job

Final checks.

• All four plugs were started by hand and tightened accurately. All coils are seated, fastened, and electrically connected.
• The intake is fully reassembled, no openings remain uncovered, and the battery is secure with its positive cover restored.
• Start only after removing tools and completing the battery reconnection checks. A new rough idle, misfire, or persistent warning needs investigation before driving.
• Complete the applicable owner manual initialization checks and record the date, mileage, plug identity, and any defects found.

How UpKeep approaches the work.

UpKeep reviews the vehicle and service history, separates scheduled plug replacement from misfire diagnosis, and verifies the plug specification. The work includes checking accessible coil boots and plug wells, installing plugs to the engine specification, and confirming that removed intake and electrical connections are restored.