2018–2025 Honda Odyssey Battery Replacement: Step-by-Step DIY Guide

A weak battery and starting problems on my 2019 Honda Odyssey led to a full battery replacement. This guide covers the whole job: a cranking test before you start, removing the engine bay covers, swapping the battery, and reactivating the audio system after the power loss.

The repair shown is on a 2019 model and applies to the 2018–2025 Honda Odyssey generation. Confirm the correct replacement battery and any year-specific differences for your van before beginning.

Watch the Video #

Quick Summary #

The old battery dropped to 9.4 volts during a cranking test, which, together with the starting problems, pointed to a weak battery. After removing the front engine compartment cover and air intake duct, I disconnected the terminals (negative first), took out the hold-down bracket, cleaned the tray and clamps, and installed the new battery. Reconnect the terminals in reverse order — positive first, then negative — then hold the audio system’s power button for more than two seconds to clear the anti-theft message.

Tools and Supplies #

• 10 mm socket and ratchet
• Deep 10 mm socket
• Flathead screwdriver or a clip tool that fits your intake duct clips
• Wire brush and sandpaper
• Interstate 65-48/H6-AGM battery (group size H6 / 48 AGM), the Costco replacement used in this video
• MOTOPOWER MP0515A battery tester

If you prefer original Honda parts, the battery type and part number vary by year and idle-stop equipment:

• 2018–2019 LX, EX, EX-L: 31500-TZ3-100M (H6 flooded)
• 2018–2019 Touring and Elite: 31500-TZ7-AGM100M (H6 AGM)
• 2020–2025 most trims: 31500-TZ7-AGM100M (H6 AGM)

Honda uses AGM batteries with idle-stop systems and flooded batteries on models without idle stop. Do not mix the two. Verify the part against your VIN before ordering.

1. Run a Cranking Test #

Before replacing the battery, run a quick cranking test. This checks the battery voltage while the engine starts.

Select the test on the tester, then start the engine. In this case, the voltage dropped to 9.4 volts. That reading, along with the starting problems, suggested the battery was getting weak.

2. Remove the Engine Cover and Air Intake Duct #

Start by removing the front engine compartment cover, the long plastic panel across the front of the engine bay. Begin at one end and gently pull upward to release the clips, then work your way across the panel.

Next, remove the air intake duct. Release the clips that hold it in place. Clip style can vary, so use a screwdriver or tool that fits yours. These clips have a slot in the center, so a flathead screwdriver works well.

3. Disconnect the Battery Terminals #

Use a 10 mm socket to loosen the nuts on the battery terminal clamps.

Disconnect the negative terminal first. It is marked with a minus sign and usually has a black cable. Then disconnect the positive terminal, marked with a plus sign and usually covered in red. Keep both cables away from the battery terminals.

4. Remove the Hold-Down Bracket and Old Battery #

Loosen the nuts on the bracket that holds the battery in place, then remove the bracket. These nuts are also 10 mm. A deep socket makes them easier to reach.

Carefully lift out the old battery. It is heavy, so use both hands and keep it upright.

5. Clean the Tray and Terminal Clamps #

With the battery out, clean the battery tray. This one had dirt and debris in it, so I vacuumed it out.

Use a wire brush to clean the terminal clamps, then a little sandpaper on the inside surfaces where the clamps touch the battery terminals.

6. Install the New Battery #

Place the new battery in the tray with the positive and negative terminals facing the same way as before. I used an Interstate 65-48/H6-AGM battery from Costco. Put the protective battery cover back in place, reinstall the hold-down bracket, and tighten the nuts until the battery is secure.

Before reconnecting the cables, run a quick test on the new battery. There is a link to the MOTOPOWER MP0515A tester in the tools list above.

7. Reconnect the Terminals and Covers #

Reconnect the terminal clamps in reverse order: positive first, then negative. Tighten both clamps so they are secure.

Reinstall the air intake duct and secure its clips. Then put the front engine compartment cover back in place, line up the clips, and press them down gently.

8. Reactivate the Audio System #

The battery replacement is complete, but there is one final step. After the battery has been disconnected, the audio system may display an anti-theft message saying it has lost power.

To reactivate it, turn the ignition on, then press and hold the audio system’s power button for more than two seconds. The system should reconnect and return to normal.

Quick Tips #

• Disconnect negative first, reconnect positive first.
• A deep 10 mm socket makes the hold-down bracket nuts easier to reach.
• Keep the old battery upright while lifting it out.
• Clean the tray and sand the inside of the clamps before installing the new battery.
• After reconnecting, hold the audio power button for more than two seconds to clear the anti-theft message.
• Confirm the correct battery for your Odyssey year and trim before buying a replacement.

FAQ #

Which terminal do I disconnect first? #

Disconnect the negative terminal first, then the positive. When installing the new battery, reconnect them in reverse order: positive first, then negative.

Why does the audio system show an anti-theft message? #

Disconnecting the battery cuts power to the audio system. Turn the ignition on and hold the audio power button for more than two seconds to enable it again.

Does this apply to other Odyssey years? #

This replacement is shown on a 2019 Honda Odyssey and matches the 2018–2025 generation. Check your vehicle’s battery requirements and any model-specific differences before starting.