Bosch 425491 Thermocouple Oem Replacement

Product Description

The BOSCH 425491 is an OEM thermocouple designed for use in gas-fired appliances where pilot flame sensing is required. A thermocouple generates a small millivolt signal when its sensing tip is heated by a standing pilot flame, and that signal holds open the main gas valve. When the thermocouple degrades or fails, the pilot will not stay lit and the appliance shuts down. Licensed gas techs and plumbers replace this component as a standard service procedure on water heaters, boilers, and similar gas-burning equipment.

This thermocouple is suited for residential and light commercial gas appliances that use a standing pilot ignition system. It is intended as a direct OEM-style replacement, restoring the original factory-specified sensing performance without modifications to the gas valve or pilot assembly.

Key Features

• OEM part manufactured by BOSCH for direct replacement accuracy
• Generates millivolt signal to hold gas valve open during normal pilot operation
• Designed for standing pilot ignition systems in gas-fired appliances
• Replaces a failed thermocouple without requiring valve or pilot hood modifications

Compatibility

Designed as an OEM-style replacement thermocouple for BOSCH gas-fired appliances equipped with standing pilot ignition systems.

Installation Notes

Installation should be performed by a licensed plumber or gas technician in accordance with local codes and the applicable sections of the International Fuel Gas Code. Shut off the gas supply and allow all components to cool completely before beginning work. The thermocouple tip must be positioned correctly in the pilot flame to ensure adequate millivolt output. Do not overtighten the thermocouple connection at the gas valve; hand-tight plus a quarter turn is the general industry practice for this fitting type.

Technical Specifications

• Part Type: Thermocouple
• Ignition System: Standing Pilot

Standard Information

• Brand: BOSCH
• Manufacturer Part Number: 425491