Welcome to CAT ET 2019C — Your First Session
Caterpillar ET 2019C is one of the most powerful OEM diagnostic tools available for any heavy equipment or truck engine. If you are new to CAT ET, this guide takes you from installation to your first fault code read in under 20 minutes.
Pre-Flight Checklist
- ✅ CAT ET 2019C installed and activated on Windows 10 or 11 (64-bit)
- ✅ CAT Communication Adapter 3 (CA3) or NexIQ USB-Link 2/3 connected via USB
- ✅ CA3 or NexIQ adapter drivers installed before launching CAT ET
- ✅ CAT engine or equipment with key-on
Step 1 — Find the Service Connector
On trucks: 9-pin Deutsch connector under the dash, driver side (Kenworth T800, Peterbilt 379 with CAT C15).
On CAT equipment:
- Excavators (320, 330, 349): left side cab console panel
- Dozers (D6, D8, D9): right side cab panel near operator seat
- Wheel Loaders (950–990): inside cab, dash left side
Step 2 — Connect the Adapter
- Plug the CA3 cable into the service connector — push until it clicks
- Plug the USB end into your laptop
- Turn the truck ignition or equipment key to ON
Step 3 — Open CAT ET and Start a Session
- Launch CAT ET 2019C — right-click → Run as Administrator on first use
- Click Connect or New Session
- CAT ET detects the connected ECMs automatically — on a CAT excavator you may see 5–8 ECMs (engine, hydraulic, transmission, machine, etc.)
- The Session Information screen shows: ECM part number, serial number, flash file part number, software revision
Step 4 — Read Fault Codes
- Left panel → Diagnostics → Fault Codes
- Select which ECM to read (Engine ECM first)
- CAT ET displays Active (currently detected) and Logged (historical) faults
- Click any fault for full description, freeze frame data, and occurrence count
- Important: CAT ET also shows Event Codes — these are informational events that are not faults but indicate the engine experienced a protection event (overspeed, high coolant temp, etc.)
Step 5 — View the Event Log
The Event Log is one of CAT ET’s most valuable features — it shows every protection event recorded by the ECM since the last event log clear, with timestamps and engine hours.
- Left panel → Diagnostics → Event Log
- Review all logged events by date/hour
- Look for: high coolant temperature events, low oil pressure events, overspeed events, VVA pressure events
The event log is the only way to diagnose intermittent faults that occur on the road and do not produce active codes by the time the machine reaches the shop.
Step 6 — Live Parameters
- Left panel → Service → Product Status Report or Parameters
- Key parameters to monitor on a CAT C15/C18 engine:
- Engine coolant temperature (normal operating: 180–205°F)
- Engine oil pressure (normal: 25–70 PSI at operating temp)
- Fuel delivery pressure (normal: 65–75 PSI at idle)
- Exhaust back pressure (normal: below 3 PSI at idle)
- DPF differential pressure (monitors soot accumulation)
Step 7 — Programmable Parameters (Advanced)
CAT ET 2019C is unique in giving access to programmable parameters — engine protection thresholds, maximum speed settings, PTO configuration, idle shutdown timers. These are typically set at the factory but can be customized for the application.
- Left panel → Service → Configuration
- View current programmable parameter settings
- Modifying parameters requires the CAT factory password for protected values — contact your CAT dealer
Beginner Mistakes to Avoid
- ❌ Using an ELM327 or passenger car OBD-II adapter — requires RP1210 or CA3 adapter
- ❌ Ignoring Event Codes — they record real incidents even when no active fault code is present
- ❌ Interrupting an ECM programming session — this can corrupt the ECM
- ❌ Running CAT ET without Administrator privileges
- ❌ Attempting to modify protected parameters without the CAT factory password
