DEF Ignition Coil for Husqvarna 435/435E/440/440E/445/445E/450/450E – Replaces 573935702, 505427201, 573935701, 544243801

DEF ignition coil is engineered as a direct replacement for select Husqvarna chainsaws. It aligns with factory specifications for models including 435, 435E, 440, 440E, 445, 445E, 450, and 450E. This coil replaces part numbers 573935702, 505427201, 573935701, and 544243801, offering a seamless swap when it's time for ignition maintenance.

Designed to fit and perform

The coil's compact form fits snugly inside the ignition housing, reducing fit issues and ensuring a clean electrical path for each spark. Built with durable insulation and corrosion-resistant materials, it withstands the exposures typical in wood-cutting tasks, from dusty underbrush to wet conditions after rain.

• Direct fit for quick installation with common tools
• OEM-style electrical characteristics to support reliable spark
• Resilient construction designed for regular field use
• Low-profile design that harmonizes with factory wiring harnesses

Each unit undergoes electrical continuity testing and heat tolerance checks to help ensure reliability in outdoor conditions.

Real-world use and benefits

In daily maintenance and demanding work, a dependable ignition coil can contribute to easier starts and steadier running. While performance can vary with engine condition and fuel, users typically notice fewer cold-start hiccups when the coil is in good condition, along with improved throttle response during sustained cuts.

• Seasonal maintenance: replace aging coils to reduce starting issues
• Active job sites: maintain momentum with quick, reliable starts
• Mid-range saws: support consistent ignition for stable cutting power

Installation tips and care

To install, disconnect the spark plug boot, remove the old coil, and mount the new DEF coil using the same hardware. Reconnect leads, re-seat the boot, and run a quick engine test according to the owner's manual. Store spare parts in a dry, cool area.

Quality and compatibility you can trust

DEF parts offer OEM-aligned fit and materials designed for durability under typical yard care conditions. This coil is intended to restore original ignition behavior on compatible Husqvarna saws. Note that results depend on overall engine health and operating conditions.