This document is the 2013 PACCAR MX Diagnostic Service Manual covering MX EGR valve U1574 codes, specifically fault code U1574 which indicates erratic, intermittent, or incorrect EGR valve module temperature data. Published by PACCAR for technicians diagnosing emissions system faults on EPA 2013-compliant MX engines, this manual provides detailed diagnostic procedures, electrical diagrams, and step-by-step repair guidance for communication and sensor issues affecting the EGR valve actuator system.
The U1574 code relates to CAN bus communication errors rather than mechanical component failure, requiring mechanics to verify E-CAN network integrity and EGR valve module functionality using the DAVIE diagnostic tool and a breakout harness.
Document details and specifications — MX EGR valve
| Brand | PACCAR |
| Model coverage | MX engines (EPA 2013) |
| System/Group | DTCs / MX Engines (EPA2013) |
| Publication no. | U1574 / Service Manual pages 435–438 |
| Year/Revision | 2013 |
| Pages | 4 |
| File size | 0.6 MB |
| Format | |
| Language | English |
Table of contents
- Code U1574 – EGR valve module temperature data erratic, intermittent, or incorrect
- Fault code information (trip count, drive cycle recovery, freeze frame type)
- Description and location of components
- Diagnostic conditions and set/reset criteria
- Electrical diagrams (2 pages)
- Technical data and possible causes (E-CAN communication, faulty EGR valve module)
- Additional information on EGR valve actuator and smart actuator diagnostics
- Diagnostic step-by-step procedures (4 steps: visual inspection, data check, repair/replace, engine support contact)
- Verification drive cycle procedure
Applies to these models
This MX EGR valve U1574 codes manual applies to trucks equipped with PACCAR MX engines meeting EPA 2013 emissions standards. The diagnostic procedures target the EGR valve module (L095) and its communication interface with the PCI ECU (D420) via the E-CAN network. Repair and diagnostic information covers the EGR valve actuator temperature sensor and its printed circuit board diagnostics. For official engine and vehicle specifications, see PACCAR official website.
Who needs this MX EGR valve U1574 codes manual
Heavy-duty diesel truck mechanics and workshop owners troubleshooting emissions faults, DTC activation, and CAN bus communication errors on PACCAR MX-powered vehicles need this manual. Technicians performing electrical diagnostics on EGR valve actuators and actuator ECU modules will find the electrical diagrams, technical data, and four-step diagnostic procedure essential for efficient fault resolution.
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