2021 Honda Accord Serpentine Belt Replacement — 1.5T and 2.0T

I replaced the serpentine belt on my 2021 Accord at 90,000 miles after noticing a faint squeal on cold starts. It wasn't slipping — just a hairline crack pattern starting to show on inspection. Honda recommends inspecting it every 30,000 miles and replacing at first sign of cracking. This is a 45-minute DIY job with basic tools. Here's exactly how I do it.

Which Engine Do You Have?

The 2021 Honda Accord uses two engines:

• 1.5T (L15B7) — 192 hp, standard in LX, Sport, EX, EX-L
• 2.0T (K20C4) — 252 hp, available in Sport 2.0T, Touring 2.0T

The serpentine belt routing is different between these engines. Make sure you have the correct diagram before starting.

Belt Specs

1.5T (L15B7)

Item	Spec
OEM belt part number	Honda 31110-5PA-A01
Aftermarket equivalents	Gates K040310, Dayco 5040310, Goodyear 4040310
Belt dimensions	4-rib, approximately 31.0" effective length
Tensioner bolt size	12mm
Tensioner rotation	Clockwise (to relieve tension)

2.0T (K20C4)

Item	Spec
OEM belt part number	Honda 31110-6A0-A01
Aftermarket equivalents	Gates K060518, Dayco 5060518
Belt dimensions	6-rib, approximately 51.8" effective length
Tensioner bolt size	14mm
Tensioner rotation	Clockwise (to relieve tension)

Check under the hood. The accessory belt routing diagram sticker is on the underside of the hood or on the plastic engine cover shroud. If it's missing, print one from Honda's service information or measure the old belt before removal.

Tools Needed

• 12mm socket + ratchet (1.5T) or 14mm socket + ratchet (2.0T)
• Breaker bar (the tensioner is spring-loaded and stiff)
• Belt diagram (photo the old routing before removal)
• Flashlight
• New serpentine belt

Step-by-Step: 1.5T Engine

1. Locate the Belt and Diagram

Open the hood. The 1.5T serpentine belt drives: alternator, AC compressor, and crankshaft pulley. The belt is on the front of the engine, driver's side. Photo the current belt routing before touching anything.

2. Relieve Tension

The automatic belt tensioner is a spring-loaded pulley on a pivot arm. It has a 12mm bolt head on the tensioner arm that you rotate to move the tensioner against spring pressure.

• Insert your 12mm socket + breaker bar into the tensioner bolt
• Rotate the tensioner arm clockwise (toward the alternator) to relieve tension
• The belt will go slack

3. Slide the Belt Off

With tension relieved, slide the belt off the alternator pulley first. Once it's off one pulley, the rest slide off easily. Remove the belt completely.

4. Route the New Belt

Using your diagram/photo, route the new belt around all pulleys except the tensioner pulley last. The standard routing order: Crankshaft pulley → AC compressor → Alternator → Tensioner (last).

5. Set the Belt on the Tensioner

With the belt routed around all other pulleys, use your breaker bar on the tensioner, rotate clockwise, and slip the belt over the tensioner pulley. Release the breaker bar slowly — the tensioner springs back and takes up slack.

6. Verify Alignment

Every belt rib must sit cleanly in every pulley groove. Look down each pulley from above with a flashlight. A misaligned belt will squeal and wear within hours.

7. Start and Verify

Start the engine and listen for squealing. Let it idle 2–3 minutes. No squeal = correct.

Step-by-Step: 2.0T Engine

The 2.0T procedure is the same concept but with a 6-rib belt and 14mm tensioner bolt. The 2.0T Accord belt drives: alternator, AC compressor, and crankshaft pulley. Tensioner rotation is clockwise to relieve tension.

Additional note for the 2.0T: the tensioner on the K20C4 has a wear indicator mark on the tensioner arm housing. When the tensioner indicator mark reaches the wear limit line, the tensioner spring is weakened and the tensioner assembly should be replaced along with the belt.

When to Also Replace the Tensioner and Idler

If your Accord has over 100,000 miles and you're replacing the serpentine belt:

• Inspect the tensioner pulley for bearing roughness — spin it by hand with the belt off. Any roughness, grinding, or wobble = replace the tensioner assembly
• Inspect idler pulleys (smooth, no grooves) — same spin test
• Replacing tensioner and idler pulleys at the same time as the belt is smart economics — the labor is already done

Common Mistakes

1. Forgetting to photo the belt routing. Once the old belt is off, it's not obvious how it routed without a reference. Always photograph the existing routing before removal.

2. Not checking rib seating. A belt that's installed with even one rib off-groove will squeal and walk off within miles. After installation, use a flashlight and look at every pulley face-on. Every rib must be fully seated.

3. Installing the wrong belt. Gates K040310 (1.5T, 4-rib) and K060518 (2.0T, 6-rib) are completely different belts. Double-check your engine code before ordering.

4. Not checking tensioner condition. A new belt on a worn tensioner will squeal within weeks. If the tensioner indicator is at or past the wear mark, replace it now.

Cost Comparison

	DIY	Honda Dealer
Belt (OEM or Gates)	$20–$40	—
Tensioner (if needed)	$60–$90	—
Labor	$0	$120–$180
Total belt only	$20–$40	$140–$220

Saving $100–$180 for 45 minutes of work.

For more Honda Accord maintenance, see the 2021 Honda CR-V cabin air filter guide — same Honda generation, similar service philosophy. Browse all 28+ repair procedures at OwnerDrop.

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