27 Caterpillar diagnostic codes on file — with the full diagnosis, repair steps, and field insights open to read free, no signup required.
Disclaimer: General reference information for trained, qualified technicians only. Codes and procedures vary by model, serial number and software version. Always follow the manufacturer's service manual and your site's safety procedures. Use at your own risk. Not affiliated with or endorsed by any manufacturer.
| Code | System | Symptom | Full fix |
|---|---|---|---|
| 12 | C9 Flash Codes | Coolant Level Sensor | View fix |
| 13 | C9 Flash Codes | Fuel Temperature Sensor | View fix |
| 15 | C9 Flash Codes | Injection Actuation Pressure (IAP) | View fix |
| 21 | C9 Flash Codes | 5V / 8V Sensor Power Supply | View fix |
| 24 | C9 Flash Codes | Engine Oil Pressure Sensor | View fix |
| 25 | C9 Flash Codes | Boost Pressure Sensor | View fix |
| 26 | C9 Flash Codes | Atmospheric Pressure Sensor | View fix |
| 27 | C9 Flash Codes | Coolant Temperature Sensor | View fix |
| 28 | C9 Flash Codes | Throttle Position Calibration | View fix |
| 32 | C9 Flash Codes | Throttle Position Signal | View fix |
| 34 | C9 Flash Codes | Engine Speed Signal | View fix |
| 35 | C9 Flash Codes | Engine Overspeed Warning | View fix |
| 37 | C9 Flash Codes | Fuel Pressure Sensor | View fix |
| 38 | C9 Flash Codes | Intake Manifold Air Temp | View fix |
| 39 | C9 Flash Codes | IAP System Fault | View fix |
| 42 | C9 Flash Codes | Engine Timing Calibration | View fix |
| 46 | C9 Flash Codes | Low Oil Pressure | View fix |
| 51 | C9 Flash Codes | ECM Battery Power | View fix |
| 55 | C9 Flash Codes | No Codes Detected | View fix |
| 56 | C9 Flash Codes | Check System Parameters | View fix |
| 61 | C9 Flash Codes | High Coolant Temp | View fix |
| 62 | C9 Flash Codes | Low Coolant Level | View fix |
| 63 | C9 Flash Codes | Low Fuel Pressure | View fix |
| 64 | C9 Flash Codes | High Intake Air Temp | View fix |
| 65 | C9 Flash Codes | High Fuel Temperature | View fix |
| 71-76 | C9 Flash Codes | Cylinder #X Injector Fault | View fix |
| 92-95 | C9 Flash Codes | Intake Valve Actuator (IVA) | View fix |
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