CAN Extension Harness 9in Length

The HOLLEY CAN Extension Harness 9in Length (part number 558-428) is a specialized wiring extension designed to bridge gaps in CAN-bus communication networks on modern engine control systems. This 9-inch black rubber-coated harness extends connectivity between CAN modules when direct wiring is impractical due to component spacing or routing constraints, maintaining signal integrity across electronic fuel injection, ignition, and sensor networks that rely on the Controller Area Network protocol.

The rubber coating protects against abrasion and moisture ingress—critical in engine bays where vibration, heat cycling, and corrosive environments degrade unshielded connections. At 9 inches long, this harness provides enough reach to relocate modules or interface aftermarket control units without requiring custom fabrication. The compact design minimizes routing complexity while the durable outer jacket resists fuel contact, oil exposure, and temperature fluctuations typical in performance and street-driven applications. HOLLEY's CAN harness architecture ensures impedance matching and proper signal termination, preventing communication dropout or data corruption that could trigger check-engine codes or sensor faults.

This extension harness is essential for builders installing HOLLEY EFI systems, swapping engine controllers, or integrating auxiliary modules in custom installations. It addresses the common challenge of bridging controller-to-harness distances on mid-engine conversions, late-model engine transplants, and vehicles with non-standard wiring layouts. The individual extension unit allows incremental network expansion without replacing entire harness assemblies, reducing waste and enabling staged system buildouts.

CAN-bus systems demand reliable, properly shielded connections to maintain the millisecond-precision timing required by modern engine management. A loose or corroded CAN connection will not trigger an immediate fault—it degrades gradually, causing intermittent misfires, sensor reading errors, or system hangs that are difficult to diagnose. The HOLLEY CAN Extension Harness eliminates the need for improvised splicing or daisy-chaining adapters, ensuring factory-level signal quality on both OEM applications and competitive builds.