Husqvarna YTH21K42 - User Manual

Questions and Answers

G
George YangAug 22, 2025
What to do if Husqvarna YTH21K42 Lawn Mower engine will not turn over?
- E
  Erin SmithAug 22, 2025
  If the engine on your Husqvarna Lawn Mower won't turn over, check these items: * Make sure the brake pedal is depressed. * Ensure the attachment clutch is disengaged. * Check for a weak or dead battery; recharge or replace if necessary. * Look for a blown fuse and replace it. * Clean any corrosion from the battery terminals. * Inspect for loose or damaged wiring. * Check or replace the ignition switch if faulty. * Check or replace the solenoid or starter if faulty. * For faulty operator presence switch(es), contact an authorized service center/department.
U
utrujilloAug 25, 2025
Why Husqvarna Lawn Mower engine "back-fires” when turning engine “OFF”?
- S
  sandersaliciaAug 25, 2025
  If your Husqvarna Lawn Mower engine back-fires when you turn it off, it could be because: * The engine throttle control is not set between half and full speed (fast) position before stopping the engine: Move the throttle control between half and full speed (fast) position before stopping the engine.
K
Kathleen ShepherdAug 28, 2025
Why Husqvarna YTH21K42 has poor cut that is uneven?
- J
  Jennifer HodgesAug 28, 2025
  An uneven cut from your Husqvarna Lawn Mower may result from: * A worn, bent, or loose blade: Replace the blade and tighten the blade bolt. * The mower deck not being level: Level the mower deck. * A buildup of grass, leaves, or trash under the mower: Clean the underside of the mower housing. * A bent blade mandrel: Replace the blade mandrel. * Clogged mower deck vent holes from buildup of grass, leaves, and trash around mandrels: Clean around mandrels to open vent holes.
A
amanda66Aug 30, 2025
Why Husqvarna Lawn Mower battery will not charge?
- A
  Andres ClarkAug 30, 2025
  If your Husqvarna Lawn Mower battery isn't charging, consider these possibilities: * The battery may have bad cell(s); replace the battery. * There might be poor cable connections; check and clean all connections. * The regulator could be faulty (if equipped); replace the regulator. * The alternator might be faulty; replace the alternator.
L
lindseycarterSep 1, 2025
What to do if Husqvarna YTH21K42 is hard to start?
- W
  watkinssamanthaSep 1, 2025
  If your Husqvarna Lawn Mower is hard to start, it could be due to several reasons: * A dirty air filter: Clean or replace the air filter. * A bad spark plug: Replace the spark plug. * A weak or dead battery: Recharge or replace the battery. * A dirty fuel filter: Replace the fuel filter. * Stale or dirty fuel: Empty the fuel tank and refill it with fresh, clean gas. * Loose or damaged wiring: Check all wiring. * Carburetor out of adjustment: See “To Adjust Carburetor” in Service Adjustments section. * Engine valves out of adjustment: Contact an authorized service center/department.
C
christopheratkinsSep 3, 2025
What to do if Husqvarna YTH21K42 Lawn Mower has poor grass discharge?
- W
  Whitney McdonaldSep 3, 2025
  If your Husqvarna Lawn Mower has poor grass discharge, consider the following: * Ensure the engine speed is not too slow by placing the throttle control in the “FAST” position. * Avoid traveling too fast; shift to a slower speed. * Allow wet grass to dry before mowing. * Level the mower deck. * Check tires for proper air pressure if it is low or uneven. * Replace worn, bent, or loose blades and tighten the blade bolt. * Clean any buildup of grass, leaves, or trash under the mower. * Replace a worn mower drive belt. * Reinstall blades with the sharp edge down. * Replace improper blades with those listed in the parts manual. * Clean around mandrels to open vent holes if they are clogged with grass, leaves, or trash.
K
Kelly HowardSep 5, 2025
Why Husqvarna YTH21K42 Lawn Mower engine clicks but will not start?
- M
  mweaverSep 5, 2025
  If your Husqvarna Lawn Mower engine clicks but doesn't start, the issue might be: * A weak or dead battery: Recharge or replace the battery. * Corroded battery terminals: Clean the battery terminals. * Loose or damaged wiring: Check all wiring. * A faulty solenoid or starter: Check or replace the solenoid or starter.
K
kaitlinbrownSep 7, 2025
How to fix excessive vibration in Husqvarna YTH21K42 Lawn Mower?
- S
  Sue MartinSep 7, 2025
  Excessive vibration in your Husqvarna Lawn Mower can be due to: * A worn, bent, or loose blade: Replace the blade and tighten the blade bolt. * A bent blade mandrel: Replace the blade mandrel. * Loose or damaged parts: Tighten any loose parts and replace any damaged parts.
D
Douglas PeckSep 9, 2025
Why Husqvarna YTH21K42 Lawn Mower blades will not rotate?
- T
  Thomas SullivanSep 9, 2025
  If the blades on your Husqvarna Lawn Mower won't rotate, it could be due to: * An obstruction in the clutch mechanism: Remove the obstruction. * A worn or damaged mower drive belt: Replace the mower drive belt. * A frozen idler pulley: Replace the idler pulley. * A frozen blade mandrel: Replace the blade mandrel.
J
Jasmine WeberSep 12, 2025
Why Husqvarna Lawn Mower headlight(s) not working?
- C
  Chelsea LewisSep 12, 2025
  If the headlight(s) on your Husqvarna Lawn Mower are not working, check the following: * Ensure the switch is turned “ON.” * Replace any burned-out bulbs or lamps. * Check or replace a faulty light switch. * Inspect the wiring and connections for any looseness or damage. * Replace any blown fuses.

Summary

Safety Rules

General Operation

Essential guidelines for operating the tractor safely and effectively.

Slope Operation

Children

Safety warnings regarding children around the machine.

Safe Handling of Gasoline

Precautions for handling flammable fuel safely.

Operation

Know Your Tractor

To Stop Mower Blades

To Operate on Hills

Before Starting the Engine

To Start Engine

Maintenance

Maintenance Schedule

Overview of regular maintenance tasks and intervals.

Before Each Use

Brake Operation

How to check and ensure proper brake function.

Service and Adjustments

To Level Mower

To Check Brake

Storage

Fuel System

Troubleshooting

Will Not Start

Common causes and solutions for engine not starting.

Engine Will Not Turn Over

Mower Blades Will Not Rotate

Troubleshooting why the mower blades are not spinning.

Suggested Guide for Sighting Slopes for Safe Operation

Husqvarna YTH21K42 Specifications

General

Cutting Width	42 inches
Transmission	Hydrostatic
Deck Material	Steel
Engine Manufacturer	Kohler
Engine Power	21 hp
Transmission Type	Hydrostatic
Cutting Height	1.5 to 4 inches