The Honda OEM Coolant Pipe O-Ring seals the connector pipe joint in applicable Honda and Acura cooling systems. This genuine replacement seal is identified by part number 91315-PNA-003 and Honda's nominal size designation 19.3 x 3.8.

Also called a connector pipe O-ring or bypass pipe O-ring, it provides the seal at the pipe connection rather than replacing the pipe or housing itself. A damaged seal at this joint can allow coolant to escape. Replacing the O-ring during connector pipe service restores the sealing component while retaining serviceable surrounding parts.

This individual service part is useful during cooling-system repairs and engine maintenance when the original connector pipe seal is damaged or has been disturbed during disassembly.

Features

• Genuine Honda OEM replacement: Part number 91315-PNA-003.
• Connector pipe seal: Used at the applicable cooling-system pipe connection.
• Factory size designation: O-Ring (19.3 x 3.8).
• Individual service component: Replaces the seal without including a new pipe, thermostat, or housing.
• Honda and Acura applications: Cataloged for selected Civic, Accord, CR-V, Crosstour, Element, RSX, TSX, RDX, and ILX applications.
• Sold individually: One O-ring per ordered unit.

Additional Information

• Manufacturer: Honda
• OEM part number: 91315-PNA-003
• OEM description: O-Ring (19.3 x 3.8)
• Alternative names: Connector pipe O-ring; bypass pipe O-ring; coolant pipe seal
• Product type: Cooling-system sealing ring
• Quantity: One O-ring

Common Reasons for Replacement

• Coolant seepage traced to the connector pipe seal.
• A cracked, cut, flattened, or otherwise damaged O-ring.
• Replacement of the sealing ring during connector pipe removal or related cooling-system service.

Installation Notes

1. Allow the engine and cooling system to cool completely before opening the system. Never remove a cooling-system cap while the system is hot or pressurized.
2. Follow the vehicle's service procedure for draining coolant and accessing the connector pipe. Access and disassembly requirements vary by application.
3. Remove the old O-ring and inspect the pipe, sealing groove, and mating bore for damage or corrosion. Avoid scratching the sealing surfaces.
4. Install the replacement seal using the lubricant and assembly method specified in the applicable service information. Keep the O-ring seated evenly without twisting or pinching it.
5. Reassemble using the vehicle-specific fastening specifications, then refill and bleed the cooling system according to the service procedure.
6. Inspect the repaired connection for coolant leakage after service.

Popular Performance Applications

A service replacement for supported K-Series cooling-system assemblies during engine maintenance, rebuilds, and restoration. In an engine-swap installation, compatibility depends on the connector pipe and housing retained in the build; the chassis alone does not establish fitment.

What's Included

One genuine Honda 91315-PNA-003 connector pipe O-ring. Pipes, housings, thermostats, coolant, hardware, and other seals are sold separately.

Renew the connector pipe seal with the genuine Honda service part specified for the application. This individually sold O-ring provides a focused replacement when the seal requires attention and the surrounding components remain serviceable.