This EPA CAN troubleshooting U111CB guide is an essential diagnostic resource published by PACCAR for mechanics and workshop owners servicing MX-series engines equipped with EPA 2004 and EPA 2013 emission systems. The document provides systematic step-by-step procedures to isolate and resolve CAN network-related diagnostic trouble codes (DTCs), particularly U-codes that indicate communication failures on the vehicle’s controller area network.
The EPA CAN troubleshooting U111CB guide covers four major diagnostic phases: investigating related P-code DTCs, performing component and power checks, isolating faulty CAN networks or components, and clearing DTCs using DAVIE diagnostic software.
Document details and specifications — EPA CAN troubleshooting
| Brand | PACCAR |
| Model coverage | MX_EPA13, MX_EPA04 engines |
| System/Group | DTCs / MX Europe Engines (EPA 2004) |
| Publication number | U111CB |
| Year/Revision | August 18, 2017 |
| Pages | 7 |
| File size | 0.1 MB |
| Format | |
| Language | English |
Table of contents
- Step 1: Investigate related DTCs (Step 1A: Check for active P-code DTCs; Step 1B: Visual inspection of aftermarket communication devices)
- Step 2: CAN-related component and power checks (Step 2A: Visual inspection of connections and wiring; Step 2B: Electrical checks and supply voltage)
- Step 3: Isolate faulty CAN network or component (Step 3A: V-CAN network resistance checks; Step 3B: V-CAN termination resistors; Step 3C: E-CAN termination resistors; Step 3D: A-CAN termination resistors)
- Step 4: Clear CAN-related DTCs (Step 4A: Use DAVIE to confirm DTC clearance)
Applies to these models
This PACCAR MX EPA CAN guide applies to trucks equipped with MX_EPA13 and MX_EPA04 engines. It covers diagnostics for V-CAN, E-CAN, and A-CAN networks, including PCI ECU (D420), EAS-3 ECU (D374), VTG turbo charger actuator (L037), NOx sensors (F843, F844), and humidity sensors (F852). The procedures assume proper supply power and ground to the PCI ECU and require DAVIE diagnostic software for code clearing and verification. PACCAR official website
Who needs this EPA CAN troubleshooting U111CB guide
Professional diesel truck mechanics and workshop owners diagnosing CAN network faults on PACCAR MX-series engines need this CAN troubleshooting U111CB guide. It is essential for technicians working with U-codes and communication errors on EPA 2004 and EPA 2013 compliant engines, providing the precise electrical test points and resistance values required for accurate fault isolation.
The complete CAN troubleshooting U111CB guide PDF is available in the DiagTechPro manuals library. A free account is required to download the full 7-page document.
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