The Holley EFI LS coil sub harness is a factory-style replacement for stock LS coil sub harnesses, built for use with factory LS coils and Holley EFI main harnesses that use coil-on-plug connectors. It's built with the same connectors and wire loom used across all Holley EFI harnesses.
Specifications:
- OEM-style connectors for a secure ECU-to-coil connection
- Techflex F6 braided wire loom for abrasion resistance
- Plug-and-play fitment
- Fits truck coils and 2005+ LS car engines; does not fit LS1 or LS6 coils
- Application: GM, LSX, universal
- Part Number: 558-321
Can also be used to replace a damaged factory coil harness.
FAQ
What coils does the 558-321 harness fit?
Truck coils and 2005-and-newer LS car engines. It does not fit LS1 or LS6 coils.
Can this replace a damaged factory harness?
Yes, it can be used to replace a damaged factory LS coil harness.
What connectors does it use?
OEM-style connectors that provide a secure connection between the ECU and ignition coils.
What is it made from?
Techflex F6 braided wire loom over the wiring for a clean look and abrasion resistance.

