🔧 IS - 12V Battery Replacement

On your IS, the 12V battery powers starting, lights, locks, and all the vehicle electronics. Replacing it is straightforward, but the order you disconnect/reconnect the cables matters to avoid sparks and electrical damage.

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

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⚠️ Safety & Precautions

• ⚠️ Keep the key fob at least 10 feet away so the car can’t “wake up” while you work.
• ⚠️ Do not let a tool touch both the battery terminal and metal body at the same time (this can short the battery).
• ⚠️ Disconnect negative (-) first and reconnect negative (-) last.
• ⚠️ Wear gloves and safety glasses; batteries can vent corrosive gas/liquid.
• ⚠️ Battery disconnect is recommended for this job (you will lose clock/radio settings).

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🔧 Required Tools

You'll need the following tools for this repair:

• 10mm socket
• 12mm socket
• 1/4" ratchet
• 3/8" ratchet
• 6" socket extension
• Trim clip removal tool
• Torque wrench (inch-pound)
• Torque wrench (foot-pound)
• Battery terminal puller (specialty)
• Battery carrying strap
• Small wire brush
• Dielectric grease
• Shop towels
• Nitrile gloves
• Safety glasses

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• 12V battery (vehicle-matched size and terminal layout) - 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, shift to P, and set the parking brake.
• Open the trunk and keep it open while you work (so you don’t get locked out).
• Turn everything off: lights, climate control, and accessories.
• Wait 2-3 minutes after shutting the car off so modules go to sleep. Reduces accidental electrical activity.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Access the battery (trunk, right side)

• Open the trunk and remove the floor mat and cargo tray by hand.
• Use a trim clip removal tool to release the clips holding the right-side trunk trim panel.
• Pull the right-side trunk trim back enough to expose the battery and hold-down bracket.

Step 2: Disconnect the negative (-) terminal

• Use a 10mm socket and 1/4" ratchet to loosen the nut on the negative (-) terminal clamp.
• Twist and lift the clamp off the battery post.
• If it’s stuck, use a battery terminal puller (specialty). (A terminal puller safely lifts the clamp without prying.)
• Wrap the disconnected negative cable end with a shop towel so it can’t spring back and touch the battery.
• Torque on install: Torque to 5 N·m (44 in-lbs)

Step 3: Disconnect the positive (+) terminal

• Use a 10mm socket and 1/4" ratchet to loosen the nut on the positive (+) terminal clamp.
• Lift the clamp off the battery post and position it so it can’t touch metal.
• Torque on install: Torque to 5 N·m (44 in-lbs)

Step 4: Remove the battery hold-down

• Use a 12mm socket, 3/8" ratchet, and 6" extension to remove the hold-down bracket/fasteners.
• Set the bracket and hardware aside in a safe spot.
• Torque on install: Torque to 18 N·m (13 ft-lbs)

Step 5: Remove the old battery

• Use a battery carrying strap to lift the battery straight up and out.
• Keep it upright as you remove it. Prevents acid spills.

Step 6: Clean and prep the terminals

• Use a small wire brush to lightly clean corrosion from the inside of both terminal clamps.
• Install battery terminal anti-corrosion pads onto the battery posts.
• Apply a thin film of dielectric grease to the posts. (Dielectric grease helps prevent corrosion.)

Step 7: Install the new battery

• Place the new battery into the tray in the same orientation as the old one.
• Reinstall the hold-down bracket using a 12mm socket, 3/8" ratchet, and 6" extension.
• Torque: Torque to 18 N·m (13 ft-lbs)

Step 8: Reconnect terminals (positive first, negative last)

• Install the positive (+) clamp first using a 10mm socket and 1/4" ratchet.
• Torque: Torque to 5 N·m (44 in-lbs)
• Install the negative (-) clamp last using a 10mm socket and 1/4" ratchet.
• Torque: Torque to 5 N·m (44 in-lbs)
• Spray the terminals with battery terminal protectant spray.

Step 9: Refit trunk trim

• Reposition the trunk side trim and press the clips back in by hand.
• Reinstall the cargo tray and trunk mat.

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✅ After Repair

• Start the engine and confirm there are no warning messages that remain after a short drive.
• Reset the clock and radio presets if needed.
• Initialize power windows (if one-touch stops working): with the car on, fully lower the window, then fully raise it and hold the switch up for 2-3 seconds.
• Drive normally for 10-15 minutes to let the system relearn idle and charging behavior.

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💰 DIY vs Shop Cost

Shop Cost: $250-$450 (parts + labor)

DIY Cost: $170-$320 (parts only)

You Save: $80-$130 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.