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Subaru Forester 12V Automotive Battery Replacement Guide
How to change a dead 12 volt car battery in the engine bay of a 4th generation 2014 to 2018 Subaru Forester SUV.

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2017 Forester FB25 Engine
Loosen Counterclockwise
Pull Off Negative Terminal
This automotive maintenance tutorial was specifically written to assist owners of the fourth generation (2014, 2015, 2016, 2017 & 2018) Subaru Forester SUV with the FB25 2.5 liter four cylinder motor in changing a dead 12 volt automotive battery in the engine bay.

Owners of other Subaru vehicles such as the Outback, Impreza, Legacy, XV Crosstrek, WRX, BRZ, SVX, Tribeca, Exiga, Trezia, Levorg and Baja may also find these DIY instructions to be helpful.

The OEM battery's "Group Size" is 35 and the part number is Panasonic 55D23L 390CCA 48AH (for the 2018 model year the old battery has been replaced by part number 75D23L 470CCA 62AH).

A few compatible replacement 12V batteries with their part numbers are as follows: Optima 8020-164, Optima 8040-218, EverStart MAXX-35N (Walmart) and Bosch 35-640B.

The tools needed to remove and replace the battery include a 10mm socket and a 1/4" drive ratchet and/or a 10mm wrench.

Pull Off Wire Harness Mount
Cover & Tuck Away
Pull Off Red Plastic Cover
The first two steps are to open the hood and then move to the right (driver) side of the engine bay.

The 12 volt car battery is located behind the driver side headlight and in between the fuse box and the windshield washer filler tube.

Loosen the nut on the negative "-" terminal by turning it counterclockwise with a 10mm socket and a 1/4" drive ratchet or a 10mm wrench.

Pull the negative terminal off the "-" battery post and lift the black plastic wire harness mounting fastener off the bolt end.

Wrap the negative terminal in a small towel and tuck it away on the side of the battery to help prevent accidental electrical contact.

Gently pull the red plastic cover off the positive terminal.

Set the red plastic cover aside in a safe place.

Loosen Positive Terminal
Pull Off Positive Terminal
Loosen Battery Clamp Nuts
Loosen the nut on the positive "+" terminal by turning it counterclockwise with a 10mm socket and a 1/4" drive ratchet.

Pull the positive terminal off the "+" battery post and set it on the left side of the battery.

The battery is held in place to the engine bay by a metal bar attached to two long round metal bars with "J" hooks at the end.

Remove "J" Hook Bar
Unhook Rear "J" Bar
Lift Off Battery Clamp
Loosen the two nuts on the top of the battery hold down clamp by turning them counterclockwise with a 10mm wrench or a deep well 10mm socket.

You don't need to fully remove the two 10mm nuts.

Carefully pull the two "J" hook bars out of their mounting slots on the battery tray.

Lift the battery hold down clamp and the two "J" bars off the top of the old battery.

Avoid making contact with the two battery posts.

Battery Hold Down Bar
Lift Heat Shield Box
Old Battery Removed
Set the battery hold down clamp aside in a safe place.

Lift the plastic and foam battery heat shield box off the old battery and set it aside for re-installation later on.

Carefully lift the old battery out of the engine bay and off the tray.

Gently set the old battery on the ground and try to avoid dropping or tipping it over to prevent from having acid leak out.

Be sure to take the old battery with you to Walmart or the auto parts store to avoid having to pay a "core", "recycling" or "disposal" fee. The retailer will also make sure that the old battery is properly recycled.

If you can wait a few days for delivery, I'd recommend buying the Optima 8020-164 RedTop group size 35 battery since it has excellent reviews on Amazon.


Clean Off Battery Tray
Lower In New Battery
Replace Hold Down Clamp
Clean off any dirt or debris from the plastic battery tray in the engine bay so that the new battery will rest evenly on it.

Carefully lower the new battery into the engine bay with the positive "+" post on the left side and the negative "-" post on the right (driver) side.

Lower the heat shield cover over the top of the new battery.

Carefully lower the two "J" bars and hold down clamp over the top of the new battery.

Avoid making contact with the two battery posts.

Re-Attach Rear "J" Hook
Tighten Nut Clockwise
Re-Attach Front "J" Bar
Re-insert the two "J" hooks into their mounting holes on the front and rear of the battery tray.

Tighten the two 10mm nuts on the bars a few turns by hand to keep the "J" hooks from falling out of place.

Tighten Nuts Clockwise
Hold Down Clamp Secured
Push On Positive Terminal
Tighten the two nuts in the clockwise direction with the 10mm wrench or a deep well 10mm socket with a ratchet until they are snug.

Check that the new battery is securely in place.

If the new battery can moved, slid or rocked around on the tray, tighten the two 10mm nuts an extra turn or two.

If you've been having problems with corrosion (white or blue powder) building up on the battery terminals, consider installing some felt anti-corrosion washers over the battery posts.

Push the positive terminal on to the "+" battery post on the left (passenger) side of the new battery.

Tighten Nut Clockwise
Push On Red Plastic Cover
Push Fastener Over Bolt End
Tighten the positive terminal nut in the clockwise direction with the 10mm socket and a 1/4" drive ratchet until it is snug.

Try to avoid over tightening the terminal nut to prevent from cracking or damaging the battery post which may lead to an acid leak.

Push the red plastic cover over the top of the positive battery terminal.

Push the black plastic wire harness fastener on the negative terminal's cable over the top of the exposed bolt end on the rear battery hold down clamp bar.

Push On Negative Terminal
Tighten Nut Clockwise
New 12V Battery Installed
Push the negative terminal over the "-" battery post on the right (driver) side of the new battery.

Tighten the 10mm terminal nut in the clockwise direction until it is snug.

Try to avoid over tightening the terminal nut.

To test the new 12V battery, start the engine, turn on the headlights and flash the high beams.

Please remember to adjust the time on the clock and program your favorite radio station presets before you start driving.

Be sure to record the battery change in your SUV's service records.

For more, please check out all of my 2014-2018 Subaru Forester DIY Repair & Maintenance Guides.

If you found this guide to be helpful, please consider making a small donation by clicking on the "Donate" button located to the right of this paragraph. Thank you!
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