Caterpillar Serial & Model Number Guide

Every Caterpillar engine carries a model/serial label. Here is where to find it, what each part of the number means, and how to use it for parts, service and age.

Where to find it: the Serial Number Plate and the Information Plate mounted on the engine. Together they carry the engine serial number, the model, the arrangement number and the performance-specification number.

What the number means

Worked example — SN-prefix + serial (e.g. C6.6 / 66A00001):

Part	Meaning	Detail
`Prefix (3-char)`	Serial-number prefix	The 8-character ESN leads with a 3-character prefix identifying the engine MODEL (often a model subset). A published Cat prefix chart maps it to the model (e.g. 1DG = 3306B gen set). The facility is NOT publicly decodable from the prefix.
`Sequence (5-digit)`	Sequence number	The unit's 5-digit production sequence (00001–99999).
`Arrangement no.`	Arrangement number	Defines the specific build/parts arrangement.
`Performance spec`	Performance-specification number	Identifies the rating/performance calibration of the engine.

Using the serial number

Caterpillar identifies an engine by serial number, arrangement number and performance-specification number together — dealers need all of them for the correct components. The 3-char prefix narrows the model (via a published prefix chart); the Cat serial does NOT encode a build year through any public formula — the year comes from a Cat dealer / Cat SIS by serial. (Post-2001 the 8-char ESN is the last 8 characters of the 17-char PIN.)

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Decode rules verified against: Cat “Product Identification Information” + parts.cat.com serial identification. Figures are for reference; confirm against the official documentation for your exact unit.