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.
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.)
Common Caterpillar maintenance parts
The service parts Caterpillar's own documents list across more than one engine model. Confirm the number for your unit on its model page or data plate before ordering.
| Part | Part number | Fits | Price |
|---|---|---|---|
| Oil filter | 3890434 | 8 Caterpillar engines | PartsGeek $30.97 NAPA $45.70 eBay $82.42 |
| Oil filter | 2409393 | 5 Caterpillar engines | eBay $18.31 |
| Fuel filter | 3890433 | 4 Caterpillar engines | eBay $34.97 |
| Air filter | 612506 | 3 Caterpillar engines | PartsGeek $66.97 eBay $100.00 |
| Air filter | 2310167 | 2 Caterpillar engines | eBay $27.50 |
| Coolant filter | 24071 | 2 Caterpillar engines | PartsGeek $14.97 |
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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.