Caterpillar 3126 / 3126B HEUI Fuel Injector 183-0691

Professional Product Overview

The 183-0691 fuel injector is a diesel fuel-injection component cataloged for Caterpillar 3126-series applications and is widely cross-referenced in the aftermarket with 178-6342. Caterpillar's current parts catalog identifies 178-6342 as a Hydraulic Electronic Unit Fuel Injector, confirming the HEUI-type application rather than a conventional common-rail injector.

The injector is designed for electronically controlled, hydraulically actuated fuel delivery. In a HEUI system, engine oil pressure supplies the hydraulic energy required to generate injection pressure while the electronic engine control system determines injection timing and duration.

This architecture allows fuel delivery to be controlled independently of conventional mechanically driven injection-pump timing and provides precise injection control across different engine operating conditions.

The 183-0691 / 178-6342 family is associated with Caterpillar 3126 and 3126B industrial and heavy-equipment applications. Aftermarket catalogs specifically cross-list 183-0691, 1830691, 178-6342 and 1786342, while broader catalogs may additionally associate 128-6601, 177-4754, 178-0199, 198-6605 and certain Reman numbers with related 3126 injector families.

Important fitment policy: injector selection must ultimately be confirmed using the Caterpillar engine serial number, machine serial number, arrangement number and/or the number physically marked on the removed injector. A cross-reference number appearing in an aftermarket database does not automatically mean every injector calibration is interchangeable across every 3126/3126B/3126E application.