2020 Honda Civic: Serpentine Belt Replacement Guide

One of the most critical maintenance items under the hood of your 2020 Honda Civic is the serpentine belt. This long, ribbed belt drives most of the engine’s accessories, including the alternator, A/C compressor, and water pump. A worn or failing belt can leave you stranded, but thankfully, inspecting and replacing it is a straightforward job.

This guide covers both common engines for the 2020 Civic: the 2.0L naturally-aspirated engine (engine code K20C2) and the 1.5L turbocharged engine (engine code L15B7).

Quick Answer: Belt & Component Part Numbers

Always confirm part numbers with your vehicle’s VIN before purchasing. Parts can vary based on the specific model and factory equipment.

For Civics with the 2.0L (K20C2) Engine:

• Serpentine Belt Length & Rib Count: Approximately 1315mm to 1325mm; 7-rib
• OEM Belt Part Number: 31110-R0B-004
• Aftermarket Belt Cross-References: Gates K070519, Dayco 5070520, Continental 4070519
• Automatic Tensioner Assembly Part Number: 31170-5BA-A02
• Idler Pulley: This engine design does not use a separate idler pulley; the tensioner pulley serves this function.

For Civics with the 1.5L Turbo (L15B7) Engine:

• Serpentine Belt Length & Rib Count: Approximately 1200mm to 1210mm; 7-rib
• OEM Belt Part Number: 31110-5AY-H02
• Aftermarket Belt Cross-References: Gates K070470, Dayco 5070470, Continental 4070470
• Automatic Tensioner Assembly Part Number: 31170-59B-025
• Idler Pulley: Like the 2.0L, this engine does not use a separate idler pulley.

Belt Routing Diagram

Since a diagram can't be shown here, the most important step you can take is to use your phone to photograph the belt's path before you remove it. A simple photo or short video can save you a major headache.

For reference, here is the text-based routing path. The belt wraps around a series of grooved and smooth pulleys.

2.0L & 1.5L Engine Belt Routing (Typical Path):

The belt path starts at the bottom of the engine at the main crankshaft pulley.

1. From the crankshaft pulley (grooved), the belt travels up to the A/C compressor pulley (grooved).
2. It then moves to the alternator pulley (grooved).
3. From the alternator, it wraps down and around the water pump pulley (smooth).
4. Finally, it goes around the auto-tensioner pulley (smooth) before returning to the crankshaft pulley.

Again, verify this against the belt currently on your engine, as accessory placement can vary slightly.

How to Replace the Serpentine Belt

Replacing the belt requires a single, specialized tool: a serpentine belt tool. You can often rent one from an auto parts store. A long-handled 3/8" or 1/2" breaker bar can sometimes work, but the dedicated tool provides better leverage and access.

1. Locate the Auto-Tensioner: Find the automatic tensioner assembly. It has a pulley attached to a spring-loaded arm.
2. Release Tension: The tensioner body will have a square hole (for a 3/8" or 1/2" drive) or a hex-shaped lug cast into it. Fit your serpentine belt tool or breaker bar to this point. Rotate the tensioner arm to release the tension on the belt. The direction of rotation depends on the engine, but it will be the direction that loosens the belt.
3. Remove the Old Belt: While holding the tensioner in the released position, use your other hand to slide the old belt off a smooth pulley, like the water pump. Once it's off one pulley, you can release the tensioner and remove the belt completely.
4. Install the New Belt: Carefully route the new belt around all the pulleys according to your photo or the diagram, saving a smooth pulley for last.
5. Final Step: Release the tensioner again and slide the belt over the final pulley. Let go of the tensioner slowly, allowing it to apply pressure. Double-check that the belt is correctly seated in all the ribbed grooves on every grooved pulley. An improperly seated belt will shred itself almost immediately upon starting the engine.

Replacement Interval

Honda does not specify a strict replacement interval for the serpentine belt. Instead, they recommend regular inspections during routine maintenance.

As a general rule, you should inspect the belt every 20,000 miles and plan on replacing it preventatively between 60,000 and 100,000 miles. A belt that operates in a hot climate may need replacement sooner.

Signs of a Failing Belt or Tensioner

Listen and look for these warning signs:

• Squealing Noises: A high-pitched squeal, especially on cold starts, when turning the steering wheel, or when turning on the A/C, is a classic sign of a worn or loose belt.
• Visible Wear: Inspect the belt with a flashlight. Look for cracks, fraying along the edges, glazing (a shiny, smooth appearance on the ribbed side), or missing chunks of ribs.
• Chirping or Grinding Noises: A rhythmic chirping or a grinding/rumbling sound often points to a failing bearing in the tensioner pulley or another accessory.
• Tensioner Arm Vibration: With the engine running, watch the tensioner arm. It should remain relatively steady. If it’s bouncing or vibrating excessively, the internal spring is weak, and the entire assembly should be replaced.

If you're not comfortable performing this service yourself, don't hesitate to get help.

Find a trusted shop on Repairius.