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Toyota Yaris Serpentine Belt Replacement Guide
How to change the serpentine accessory belt on a 1NZ-FE 1.5L I4 engine in a 3rd generation 2012-2016 Toyota Yaris.

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2015 Yaris 1NZ-FE 1.5L I4
Left (Passenger) Side
Alternator & Bracket
This automotive maintenance tutorial was specifically written to assist owners of the third generation (2012, 2013, 2014, 2015 & 2016) Toyota Yaris in changing the serpentine accessory belt on the 1NZ-FE 1.5 liter inline four cylinder motor or adjusting the tension.

Owners of other Toyota, Lexus or Scion vehicles such as the Corolla, Matrix, Prius, Camry, RAV4, Sienna, Tacoma, Tundra, FJ Cruiser, Venza, Highlander, Avalon, Sequoia, Land Cruiser, IS 250, ES 350, GS 350, tC, xB, xD, iQ and FR-S may also find these DIY instructions to be helpful.

The OEM belt part number for a Yaris equipped with A/C (air conditioning) is Toyota # 90916-02705.

A few other compatible replacement belts with their part numbers are as follows: Gates K040476, Bando 4PK1210 and Dayco 5040478.

The tools needed to complete this procedure include a 12mm socket, a 14mm socket and a 3/8" drive ratchet.


Please verify the correct replacement belt for your Yaris by using the Amazon Part Finder website. The compatible part numbers may vary depending on the model year, engine type, trim level and whether or not the car has A/C (air conditioning).
Bottom Alternator Bolt
Loosen Top 12mm Bolt
Butane BBQ Lighter

The first two steps are to open the hood and then move to the left (passenger) side of the engine bay.

To release the tension on the old OEM serpentine belt, you'll have to loosen the top and bottom bolts on the alternator.

Loosen the top alternator bolt by turning it counterclockwise with a 12mm socket and a 3/8" drive ratchet.

If you have trouble loosening the bolt, warm it up for about 30 to 60 seconds with a long nose grill lighter.

Heat Up Bottom Bolt
Loosen Counterclockwise
Both Bolts Loosened
I found it very difficult to loosen the bottom alternator bolt. So I used a BBQ lighter to heat the bolt for about a minute to soften the threadlocker adhesive compound that was applied at the factory.

Loosen the bottom bolt by turning it counterclockwise with a 14mm socket and a 3/8" drive ratcheting wrench.

Don't completely remove the two bolts. They only need to be loosened a few turns.

Pivot Alternator Back
Pull Old Belt Off Pulleys
Slip Belt Off Crankshaft
Once both bolts have been loosened, firmly push back on the alternator until it rotates towards the rear of the engine bay to release the tension on the old belt.

The top bolt will pivot back to the rear of the tension adjustment bracket.

Carefully slip the old belt off the various pulleys including the alternator, water pump, A/C compressor and the crankshaft.

Removing Old Belt
Old Belt Removed
Inspect Old OEM Belt
Lift the old belt out of the engine bay.

Inspect the old belt for any damage, chunks of missing rubber, fraying or cracks.

If the old belt is in relatively good condition, consider keeping it in your trunk or at least your garage for emergency use just in case the new belt fails.

I recommend buying the genuine OEM Toyota 90916-02705 serpentine belt.

The Gates K040476 belt is also a good choice since it has excellent reviews on Amazon.


Belt Routing Diagram
Lower In New Belt
Route New Belt
If you don't have your owner's manual, I included a picture of the belt routing diagram for the 1NZ-FE 1.5L VVT-i I4 engine with A/C (air conditioning).

Lower the new belt in to the left side of the engine bay.

A good rule to remember is that the ribbed side of the belt gets wrapped around the ribbed pulleys and the smooth side goes against the smooth pulleys.

Start by wrapping the belt around the large crankshaft pulley at the bottom of the engine bay.

Belt Over A/C Compressor
Wrap Belt Around Crankshaft
Slip Belt Over Alternator
Continue wrapping the belt around the air conditioning compressor pulley, under the water pump pulley and then slip it over the top of the alternator (generator) pulley.
Lug Nut Wrench
Use Lever To Apply Tension
Tighten Top 12mm Bolt
In order to apply the correct amount of tension on the new pulley, I used the flat end of the tire iron as a lever in between the alternator and the engine block.

Firmly pull the alternator forward to pivot the top alternator bolt towards the front of the tension adjustment bracket.

Maintain the tension on the new belt with one hand on the lug nut wrench and tighten the top 12mm bolt in the clockwise direction with the other hand.

Tighten Lower 14mm Bolt
Check Belt Tension
Serpentine Belt Replaced
Tighten the bottom 14mm bolt in the clockwise direction until it is snug.

To check the tension on the new belt, grab the belt at the longest run in between the alternator and the crankshaft pulley.

Try to twist the middle of the belt until it is almost perpendicular with the rest of the belt.

If you can twist the middle section of the longest run farther than 90 degrees, the belt is too loose.

If you can't twist the belt to about 90 degrees, it might be too tight.

Once you are satisfied that the belt has the correct amount of tension, double check that the top 12mm bolt and the bottom 14mm bolt are tight.

Start the engine and listen closely for any strange sounds or noises that might indicate a problem such as an improperly routed belt, a seized pulley, excessive belt tension or not enough tension.

If you hear a loud continuous screeching or squealing sound when you start the engine, immediately turn off the ignition. The new belt might be far too tight and it won't spin on the pulleys.

Loosen the two bolts, relieve some of the tension, and tighten the bolts again.

If you hear an occasional "chirp, chirp, chirp", squeak or squeal sound, the new belt might be too loose and it is skipping on one or more of the pulleys.

Loosen the two bolts, apply some more tension with the lug nut wrench and tighten the bolts again.

Be sure to record the belt change in your vehicle's service records.

For more, check out all of my 2012-2016 Toyota Yaris DIY Repair & Maintenance Guides.

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