🔧 WRX - Battery Replacement

You’ll remove the old 12V battery, clean the terminals/hold-down, and install a new battery with the correct size and polarity. Doing it the right way prevents corrosion, starting issues, and electrical glitches.

Difficulty Level: Beginner | Estimated Time: 0.5-1.0 hours

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⚠️ Safety & Precautions

• ⚠️ Turn the car OFF, remove the key, and keep it away from the car.
• ⚠️ Never let a tool touch both battery terminals at once.
• ⚠️ Disconnect negative (-) first and reconnect negative (-) last to reduce short-circuit risk.
• ⚠️ Battery acid is corrosive—wear gloves and eye protection.
• ⚠️ The battery is heavy; lift with both hands and keep it upright.

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🔧 Required Tools

You'll need the following tools for this repair:

• 10mm socket
• 3/8" ratchet
• 3" extension
• Torque wrench (in-lb or low-range ft-lb)
• Battery terminal brush
• Trim-safe shop rags
• Nitrile gloves
• Safety glasses

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• 12V battery (Group 35, top-post) - Qty: 1
• Battery terminal anti-corrosion pads - Qty: 2
• Battery terminal protectant spray - Qty: 1

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📋 Before You Begin

• Park on level ground, set the parking brake, and pop the hood.
• Write down radio presets and set aside 10-15 minutes afterward to reset clock/settings if needed.
• If your terminals are very crusty/green, plan extra time to clean them with the battery terminal brush (a round wire brush made for battery posts/clamps).

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Open hood and locate the battery

• The battery sits at the front of the engine bay with a hold-down bracket across the top.
• Put on safety glasses and nitrile gloves.

Step 2: Disconnect the negative (-) terminal first

• Use a 10mm socket with a 3/8" ratchet to loosen the nut on the negative (-) clamp.
• Wiggle the clamp up and off the battery post (don’t pry hard).
• Tuck the negative cable to the side so it can’t spring back onto the post.

Step 3: Disconnect the positive (+) terminal

• Use a 10mm socket to loosen the nut on the positive (+) clamp.
• Lift the clamp off and move it aside so it can’t touch metal parts.

Step 4: Remove the battery hold-down bracket

• Use a 10mm socket, 3" extension, and 3/8" ratchet to remove the hold-down nuts.
• Remove the bracket and J-hooks/rods, then set them aside in the order they came off.

Step 5: Remove the old battery

• Use both hands and lift the battery straight up and out.
• Set it on the ground upright (not on its side).
• Keep it level to avoid spills.

Step 6: Clean the terminals and battery tray

• Use the battery terminal brush to clean the inside of both cable clamps until the metal looks bright.
• Wipe the tray area with shop rags and remove loose corrosion.

Step 7: Install the new battery

• Place the new battery into the tray with the posts in the same orientation as the old one.
• Reinstall the hold-down bracket and start the nuts by hand to avoid cross-threading.
• Use a torque wrench to tighten the hold-down nuts: Torque to 18 Nm (13 ft-lbs).

Step 8: Reconnect the positive (+) terminal first

• Install an anti-corrosion pad on the positive post if you’re using them.
• Push the positive clamp fully down on the post.
• Use a torque wrench with a 10mm socket: Torque to 5.4 Nm (4.0 ft-lbs).

Step 9: Reconnect the negative (-) terminal last

• Install an anti-corrosion pad on the negative post if you’re using them.
• Push the negative clamp fully down on the post.
• Use a torque wrench with a 10mm socket: Torque to 5.4 Nm (4.0 ft-lbs).
• Spray battery terminal protectant on both terminals after everything is tight.

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✅ After Repair

• Start your WRX and confirm it cranks strongly and idles normally.
• Check that the battery warning light is OFF.
• Reset the clock and re-save radio presets if they were lost.
• If the driver’s auto window function acts weird, cycle the driver window all the way down and all the way up using the switch to re-learn.
• Drop the old battery at an auto parts store for core return/recycling.

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💰 DIY vs Shop Cost

Shop Cost: $220-$380 (parts + labor)

DIY Cost: $140-$260 (parts only)

You Save: $80-$120 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 0.5-1.0 hours.

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🎯 Ready to get started?

HowToo makes it easy: same-day/2-day shipping on every part, plus all the tools and specialty tools you need! Check out the parts and tools sections below to add everything to your cart.