🔧 Crosstrek - Alternator Replacement

Your alternator charges the battery and powers the electrical system while the engine runs. Replacing it involves removing the serpentine belt, unplugging the alternator wiring, and swapping the alternator on its mounting bracket.

Difficulty Level: Intermediate | Estimated Time: 1.5-3.0 hours

---

⚠️ Safety & Precautions

• ⚠️ Disconnect the negative battery cable before touching alternator wiring (the main alternator cable is always “hot” if the battery is connected).
• ⚠️ Work on a cool engine; keep hands/clothes clear of belts and pulleys.
• ⚠️ Support the alternator as you remove the last bolt so it doesn’t drop.
• ⚠️ If you raise the front of your Crosstrek, use jack stands on proper lift points—never rely on a jack alone.

---

🔧 Required Tools

You'll need the following tools for this repair:

• Safety glasses
• Mechanic gloves
• Floor jack (rated 2-ton minimum)
• Jack stands (rated 2-ton minimum)
• Wheel chocks
• 10mm socket
• 12mm socket
• 14mm socket
• 10mm combination wrench
• 12mm combination wrench
• 14mm combination wrench
• 3/8" ratchet
• 3/8" extension set (3" and 6")
• Torque wrench (10–100 ft-lbs)
• Flat-blade screwdriver
• Pliers
• Trim clip removal tool
• Digital multimeter

---

🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Alternator - Qty: 1
• Serpentine drive belt - Qty: 1 Recommended if belt is cracked/glazed
• Battery terminal anti-corrosion pads - Qty: 1

---

📋 Before You Begin

• Park on level ground, shift to Park, and set the parking brake.
• Open the hood and let the engine cool fully.
• Disconnect the battery: use a 10mm socket to remove the negative (-) terminal and tuck it aside so it can’t spring back.
• Tip: Take a quick photo of the belt routing.

---

🔨 Step-by-Step Instructions

Follow these steps in order:

Assumption (best-effort): Standard FB20 alternator layout; fastener sizes may vary slightly by supplier—match tools to what you see.

Step 1: Remove the intake snorkel/duct for access

• Remove plastic clips using a trim clip removal tool.
• Loosen any hose clamp(s) using a flat-blade screwdriver.
• Lift the snorkel/duct out and set it aside.

Step 2: Relieve belt tension and remove the belt from the alternator pulley

• Locate the belt tensioner (spring-loaded arm with a pulley).
• Use a 14mm socket and 3/8" ratchet on the tensioner’s hex to rotate it and release belt tension.
• Slip the belt off the alternator pulley first, then slowly let the tensioner return.
• Tip: Move the tensioner slowly to avoid snapping.

Step 3: Disconnect the alternator electrical connections

• Unclip the small alternator plug by pressing the tab and pulling straight off (use pliers gently if needed).
• Remove the rubber boot on the main alternator output stud.
• Use a 10mm socket (or 10mm wrench) to remove the nut from the B+ output terminal, then remove the cable.
• Definition: B+ is the main charging cable from alternator to battery.

Step 4: Unbolt the alternator from its bracket

• Support the alternator with one hand.
• Remove the upper mounting bolt using a 12mm socket and 3/8" ratchet.
• Remove the lower mounting bolt using a 12mm socket or 14mm socket (some units vary).
• Lift the alternator up and out of the engine bay.

Step 5: Install the new alternator

• Set the new alternator into place and start both mounting bolts by hand (this prevents cross-threading).
• Tighten mounting bolts with a 12mm socket or 14mm socket.
• Torque to 35–45 Nm (26–33 ft-lbs) for alternator mounting bolts. Verify exact spec for your fasteners if available.

Step 6: Reconnect wiring

• Install the main B+ cable on the output stud and tighten the nut using a 10mm socket.
• Torque to 7–10 Nm (62–88 in-lbs) for the B+ terminal nut. Do not overtighten.
• Reinstall the rubber boot over the B+ stud.
• Plug the alternator connector back in until it clicks.

Step 7: Reinstall the serpentine belt

• Route the belt according to the under-hood diagram (or your photo).
• Rotate the tensioner again using a 14mm socket and 3/8" ratchet.
• Slip the belt fully onto the alternator pulley, then slowly release the tensioner.
• Visually confirm the belt ribs are seated in every pulley groove.

Step 8: Reinstall intake snorkel/duct

• Reposition the snorkel/duct and reinstall clips using a trim clip removal tool (to align clips) and hand pressure to seat them.
• Tighten clamps using a flat-blade screwdriver.

Step 9: Reconnect the battery

• Reconnect the negative (-) terminal using a 10mm socket.
• Snug the clamp so it won’t rotate on the post.

---

✅ After Repair

• Start your Crosstrek and confirm the battery/charging warning light turns off.
• Listen for belt squeal or slapping; if present, shut off and re-check belt alignment.
• Use a digital multimeter on the battery posts:
  • Engine off: about 12.4–12.7V for a healthy battery.
  • Engine running: typically 13.8–14.7V if charging properly.
• Re-check the B+ terminal boot is fully covering the stud.

---

💰 DIY vs Shop Cost

Shop Cost: $450-$800 (parts + labor)

DIY Cost: $180-$450 (parts only)

You Save: $270-$350 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 1.5-2.5 hours.

---

🎯 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.