This document is the PACCAR MX engine P0669 diagnostic reference from the 2013 PACCAR MX Diagnostic Service Manual. Published by PACCAR for technicians and workshop owners, it provides fault code identification, component location guidance, and diagnostic procedures for internal ECU temperature internal error conditions on EPA 2013-compliant MX engines.
The PACCAR MX engine P0669 is triggered when the engine control unit detects an internal temperature failure or sensor malfunction within the ECU itself. This fault requires immediate technical investigation and support from the PACCAR Engine Support Center.
Document details and specifications — PACCAR MX engine
| Brand | PACCAR |
| Model coverage | MX Engines (EPA 2013) |
| System/Group | DTCs / MX Engines (EPA2013) |
| Year/Revision | 2013 |
| Pages | 1 |
| File size | 0.3 MB |
| Format | |
| Language | English |
Table of contents
- Code number P0669
- Fault code description: Internal ECU temperature – Internal error
- Fault code information
- Description of component(s)
- Location of component(s)
- Diagnostic condition
- Set condition of fault code
- Reset condition of fault code
- Electrical diagram(s)
- Technical data
- Possible causes
- Additional information
- Diagnostic Step-by-Step
- Verification Drive Cycle
Applies to these models
This diagnostic reference covers PACCAR MX engines equipped with EPA 2013 emissions controls. The MX engine P0669 manual applies specifically to trucks using PACCAR’s MX-series engines certified for 2013 EPA emissions standards. For additional technical support and engine specifications, visit PACCAR official.
Who needs this MX engine P0669 manual
Diesel mechanics, engine diagnosticians, and workshop owners servicing PACCAR MX-powered trucks require this MX engine P0669 guide to accurately identify internal ECU temperature faults and follow manufacturer-recommended troubleshooting procedures. Technicians performing emissions-related diagnostics on EPA 2013 PACCAR engines will find this single-page reference essential for quick fault identification and support escalation protocols.
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