GAOSHUN Voltage Regulator Rectifier for Kohler 25-403-39-S / 25-403-32-S — 12V 20–30A direct-fit replacement with gasket

If your Kohler-powered mower, generator, or utility equipment is showing electrical issues, this GAOSHUN regulator rectifier offers a replacement solution built for compatibility and straightforward installation. Engineered to match Kohler part numbers and replace several discontinued units, it helps convert alternator output to a steady 12-volt charge while protecting battery and electronics from voltage spikes.

Will this part fit my Kohler engine model?

Yes — the GAOSHUN regulator is matched against common Kohler parts and engine model numbers to ensure compatibility. It fits the listed Kohler part references and works with multiple engine families used in lawn and garden equipment.

• Fits Kohler part numbers: 25-403-39-S and 25-403-32-S
• Replaces older or alternate numbers: 25-403-08-S, 25-403-20-S, 25-403-21-S, 25-403-05-S, 25-403-29-S
• Compatible engines include CH730-0165, CH730-0170, ECH749, ECV740 and referenced Kohler numbers 62570, 64569

How do I install the regulator rectifier on my machine?

Installation is straightforward for anyone comfortable with small-engine electrical work and basic hand tools. The unit ships with essential hardware and a gasket to match the mounting interface; follow safety steps like disconnecting the battery before starting.

• Includes: 1 regulator, 1 wiring cable, 1 mounting screw, 1 gasket for a sealed fit
• Rated output: 20–30 amp continuous at 12 volts
• Requires standard mounting to the stator/engine electrical housing and connector mating

What electrical performance and protection does this part provide?

The GAOSHUN regulator rectifier converts AC from the alternator to regulated DC and limits voltage to protect the battery and onboard electronics. Its rectifier diodes and regulator circuitry reduce ripple and prevent overcharging under normal operating conditions.

• 12-volt regulation suitable for common small-engine charging systems
• 20–30 AMP handling for typical mower and generator charging loads
• Built-in diode rectification to convert alternator AC to usable DC power

Who is this for? If you own a Kohler-powered lawn tractor, riding mower, generator, or similar equipment exhibiting charging faults, dimming lights, or battery drain, this GAOSHUN replacement regulator rectifier provides a cost-effective repair option. It's aimed at mechanics, DIY homeowners, and small-engine service professionals who need a direct-fit, clearly labeled replacement with included hardware to complete a repair quickly and reliably.