Caterpillar engine serial numbers are structured with a three-character alphanumeric prefix that defines the engine’s original build configuration and intended application. This prefix is used by Caterpillar to distinguish between industrial, on-highway truck, and locomotive engines, and it governs key technical attributes including emissions certification level, fuel system architecture, electronic control strategy, mechanical specifications, and approved component groupings.
Accurate identification of the serial number prefix is essential for correct parts lookup, service information selection, calibration matching, and compliance with Caterpillar service and overhaul procedures.
- Cat Truck Engine Serial Number Prefix
- Cat Industrial Engine Serial Number Prefix
- Cat Locomotive Engine Serial Number Prefix
- How to Locate Cat Engine Serial Number?
- How to Lookup Serial Number if Plate Is Missing?
Cat Truck Engine Serial Number Prefix
| Cat Truck Engines | Engine SN Prefix |
|---|---|
| 1140 | 36B |
| 1145 | 89V, 97B |
| 1150 | 96B |
| 1160 | 57V, 95B |
| 1673 | 70B, 74B, 83B |
| 1673B | 78B |
| 1673C | 69D, 76R |
| 1674 | 94B |
| 1676 | 54B |
| 1693 | 65B |
| 3054 | 6NR |
| 3114 | 5YL, 9LL |
| 3116 | 2BK, 2CW, 2FR, 3RJ, 5JZ, 5RM, 7AG, 7HJ, 7HS, 7JL, 7SF, 8WL, 9CJ, 9GK, 9LN, 9YN, CSM |
| 3126 | 1BW, 1WM, 4ES, 6PZ, 6RW, 7JZ, 7LZ, 8HW, 8SZ |
| 3126B | 1AJ, 5GL, 7AS, 8YL, BKD, LEF |
| 3126E | 9SZ, CKM, CRP, DPF, G3E, HEP |
| 3150 | 88V |
| 3176 | 2YG, 5XN, 7LG |
| 3176B | 9CK |
| 3208 | 02Z, 32Y, 40S, 51Z, 5CD, 62W |
| 3306 | 63Z, 69D, 76R |
| 3306B | 5KD, 63Z |
| 3306C | 2AZ, 3KS, 7RJ, 9TL |
| 3406 | 8SB, 92U |
| 3406B | 2EK, 3ZJ, 4CK, 4MG, 5KJ, 5YG, 7FB, 7XC, 8TC, |
| 3406C | 3ZJ, 4CK, 5KJ, 8PN |
| 3406E | 1LW, 1MM, 2WS, 5DS, 5EK, 6TS |
| 3408 | 28V |
| 3408B | 28V |
| 7155 | 56K, 72S |
| C7 | C7S, FML, FMM, KAL, LBM, NPH, SAP, WAX, YPG |
| C9 | 9DG, C9S, CKP, ETK, SRB, MTB |
| C10 | 2PN, 3CS, 8YS, AKB, MBJ |
| C11 | KCA, RSX |
| C12 | 1YN, 2KS, 8YF, 9NS, 9SM, ALS, CPD, MBL, TME |
| C13 | JAM, KCB, LEE |
| C15 | B5R, BXS, MHP, MXS, NXS, SDP, EGH, MBN |
| C-15 | EGH, 6NZ, 9NZ |
| C16 | W1A, 7CZ |
| C18 | CJP, MDP, MEP |
Cat Industrial Engine Serial Number Prefix
| Industrial Engines | Engine SN Prefix |
|---|---|
| 3003 | 3ZG |
| 3011C | 311, G1P |
| 3013 | 4XD |
| 3013C | 313, G3P |
| 3014 | 4GF |
| 3024 | 4RF |
| 3024C | 424, G4P |
| 3034 | 7EF |
| 3044C | 344 |
| 3054 | 5YS, 6FK |
| 3054B | 5MF |
| 3054C | 334 |
| 3054E | 304 |
| 3056 | 1ML, 7MS |
| 3056E | 356 |
| 3114 | 1ZG, 4KR, 5EF |
| 3116 | 2MR, 2WG, 4PG, 5EN, 5TS |
| 3126 | 3TR, 6MS, 9ZR, CKK |
| 3126B | BDZ, BEJ, DCD, DCS |
| 3150 | 88V |
| 3160 | 57V, 98M |
| 3176B | 3LZ, 3NL |
| 3176C | 2AW, 5DZ |
| 3196 | 1DW |
| 3204 | 2TB, 3PC, 6DC, 7EB |
| 3208 | 03Z, 90N, 9WC |
| 3304 | 02B, 04B, 10E |
| 3304B | 4XB |
| 3306 | 23C, 4WB, 64Z, 66D, 70R |
| 3306B | 1BM, 5GZ, 7JB |
| 3406 | 90U, 9HB |
| 3406B | 6TB |
| 3406C | 2MZ, 3ER |
| 3406E | 6BR |
| 3408 | 67U, BFF, DLA |
| 3408B | 67U, 9TD, BFD |
| 3408C | 9ER, 9XM |
| 3408E | 7PR, BKY, ECP |
| 3412 | 38S, 9XF, BDT, BKS, BLJ |
| 3412C | 8AR, BCS, B1A |
| 3412E | 4CR, BFT, 5JJ, BNF |
| 3456 | 3LW |
| 3508 | 68Z, 95Y, 97Y |
| 3508B | 7AF, BPX, CBB, 5XS, BTB, BTR, BWA |
| 3512 | 1LM, 2AF, 49Y, 65Z, 51Y |
| 3512B | 8DF, BRC, 6SS, CND, PWG |
| 3516 | 27Z, 71Z, 28Z |
| 3516B | 9WF, CAN, 7DS, CPW |
| 3606 | 8RB, 6MC, 7WR |
| 3612 | 9RC |
| 3616 | 1PD |
| 5650 | 30Z |
| C0.5 | C5M, C6F, C6H |
| C0.7 | C7M |
| C1.1 | C3M, G8M |
| C1.5 | C5N, G7N |
| C1.6 | C1M |
| C2.2 | C4M, G7M |
| C3.3 | E3J |
| C4.4 | 444 |
| C6.6 | 666 |
| C7 | JRA, JTF, |
| C9 | CLJ, JLW, JSC, MBD |
| C10 | BCX, Z2B |
| C11 | GLS |
| C12 | BDL |
| C13 | LGK |
| C15 | BEM, JAS, JRE |
| C16 | BFM |
| C18 | EJG, WJH |
| C27 | TWM |
| C32 | TLD |
| D320A | 63B |
| D330C | 02B, 04B |
| D333C | 09A, 23C, 62M, 62U, 66D |
| D342 | 31B |
| D342C | 49B |
| D343 | 62B |
| D346 | 39J, 98N |
| D348 | 36J, 57K |
| D349 | 61P, 32R |
| D353C | 46B |
| D353D | 46B |
| D353E | 46B, 77B |
| D379 | 68B, 76B |
| D379B | 68B, 76B |
| D398 | 66B, 75B |
| D398B | 66B, 75B |
| D399 | 35B |
| D3400 | 01T |
| D13000 | 04H, 05E |
Cat Locomotive Engine Serial Number Prefix
| Locomotive Engines | Engine SN Prefix |
|---|---|
| 3508 | 6TJ |
| 3508B | 5PS |
| 3512 | 2WK |
| 3512B | 3ZW |
| 3516 | 9KF |
| 3516B | 6HZ, BCK |
| 3516C | T2X |
| 3606 | 8RB |
| 3608 | 6MC |
| 3612 | 9RC |
| 3616 | 1PD, ZYD |
Identifying the correct serial number on a Caterpillar engine is essential for finding accurate parts, service information, and technical specifications. Every Cat industrial or truck engine - carries a unique serial number plus additional identifiers such as the Modification Number, Arrangement Number, and OEM Number.
The serial number is typically referenced on the plate by the label, “serial number” or abbreviated version, such as S/N or SER. NO. Now that you've identified your serial number, you can look up parts for your engine by model and serial number or from official CAT's Parts Manuals.
How to Locate Cat Engine Serial Number?
Every Caterpillar engine has a unique Engine Serial Number (ESN) stamped on a metal plate attached directly to the engine. This number identifies the engine model, configuration, and production series. Because the ESN is required for ordering parts, verifying specifications, and confirming compatibility, knowing where to find it is essential.
1. Look for the Serial Number Plate
The primary location of the Cat ESN is a rectangular metal plate riveted or bolted to the engine block. The exact position varies by engine family, but it is typically found in one of these common locations:
Most common ESN plate locations:
- On the left (driver’s side) of the engine block, near the front
- On the right side of the block, close to the fuel pump
- On the valve cover, especially on smaller Cat engines
- On the top surface of the timing cover
- On the rear of the block near the flywheel housing
The plate will show:
- Engine Serial Number (example: 7AS12345)
- Arrangement Number
- Performance Spec
- Model (3126, C13, C15, etc.)
2. Check for the Stamped Serial Number
In addition to the metal plate, Caterpillar also stamps the ESN directly into the engine block as a permanent identification mark.
Typical stamped locations:
- Below the serial number plate
- On a machined pad near the injection pump
- On the block rail, just above the oil pan
- Rear-right side of block near the bellhousing
This stamped number is used if the data plate is damaged or missing.
3. Check Machine Documentation
If the serial number plate cannot be found:- Original CAT heavy equipment owner’s manual
- Build sheet from machine manufacturers (Cat, Kenworth, Peterbilt, etc.)
- Service invoices
These often list the engine serial number exactly as stamped.
How to Lookup Cat Engine Serial Number if Plate Is Missing?
If the data plate is missing (common on older Cat engines), you can still recover the Engine Serial Number (ESN) using several reliable methods. Caterpillar built multiple identifiers into the engine and into the machine/vehicle that it powers, so you usually don’t need the plate itself.
Below are the most effective ways to look up a Cat engine serial number when the plate is gone.
1. Find the ESN Stamped Into the Engine Block (Most Reliable)
Caterpillar always stamps the serial number into the block as a backup. Look for a machined flat pad with hand-stamped characters.
Common stamped-ESN locations:
- Right-hand side of block near the fuel transfer pump
- Left side of block, middle area, on a flat machined pad
- Front gear housing (less common)
- Near the air compressor mounting area
The stamping may be faint, rusty, dirty, or painted over—clean with solvent and use a flashlight at a low angle.
2. Check the Vehicle / Equipment Manufacturer Labels
If the engine is in a truck, RV, or piece of equipment, the OEM often repeats the ESN.
Trucks (Freightliner, Kenworth, International, etc.)
Check:- Driver-door jamb emission/VIN label – often lists engine serial number
- Under-hood EPA emissions sticker
- Build sheet (Fleet managers usually have these)
- Dealer (truck OEM) service history
Heavy equipment (excavators, loaders, dozers)
Check:
- Equipment serial plate (may list engine SN or arrangement)
- Manufacturer’s build sheet or service manual
- Dealer service logs
3. Locate the ECM Replacement Tag or ECM Data
If the engine uses an ECM (like many 3126 truck engines), the ESN is stored electronically.
Options:
- Cat ET (Electronic Technician) at a Cat dealer
- Some aftermarket scan tools for on-road engines
- The ECM may also have a small secondary barcode sticker showing the engine or ECM serial number
Even if the ECM has been replaced, Cat dealers can cross-match the arrangement number and flash file to narrow the ESN range.
4. Use the Arrangement Number (ARN) or Core Stampings
If you have the:
- Arrangement Number (ARN)
- Core part number
- Fuel system number (HEUI pump, injector codes)
...a dealer can often reverse-look-up the correct ESN or at least the serial-prefix family (e.g., 1BW, 6PZ, 4ES for 3126 truck engines).
The arrangement number is often stamped or cast on:
- Valve cover
- Front gear cover
- HEUI pump housing tag
- Timing cover
5. Use Casting Numbers to Narrow Down the Model & Serial Prefix
Casting numbers on:
- Cylinder head
- Block
- HEUI pump
- Turbocharger
...identify the engine family, production era, and possible serial-prefix ranges. Cat dealers use these to match the correct engine serial group.
6. Check Previous Service Records
Useful sources:
- Oil analysis reports (SOS)
- Dealer invoices
- Fleet maintenance databases
- Emissions testing records
- Warranty paperwork
These often list the ESN even if the engine’s plate is gone.
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