This PACCAR MX cylinder 6 torque code P1278 diagnostic service manual is the official fault code reference published by PACCAR for 2013 MX engines certified to EPA 2013 emissions standards. The document provides technicians with structured diagnostic procedures and technical specifications for identifying and resolving cylinder 6 torque contribution faults in PACCAR MX powerplants.
The manual follows PACCAR’s standardized diagnostic layout, guiding mechanics through set conditions, reset procedures, and verification steps required to validate repairs on PACCAR MX cylinder 6 issues.
Document details and specifications — PACCAR MX cylinder
| Brand | PACCAR |
| Model coverage | MX Engines (EPA 2013) |
| System/Group | DTCs / MX Engines |
| Fault code | P1278 |
| Year/Revision | 2013 |
| Pages | 1 |
| File size | 0.3 MB |
| Format | |
| Language | English |
Table of contents
- Code number P1278
- Fault code description: Cylinder 6 combustion – Torque contribution is too high
- 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 MX cylinder 6 manual applies to 2013 and later PACCAR MX diesel engines meeting EPA 2013 emission regulations. It covers fault code P1278 which triggers when cylinder 6 torque contribution exceeds acceptable parameters. For comprehensive engine support, contact the Engine Support Center as referenced in this MX cylinder 6 diagnostic guide. PACCAR official website
Who needs this MX cylinder 6 manual
Heavy-duty diesel mechanics, truck workshop owners, and authorized PACCAR service centers require this MX cylinder 6 diagnostic reference when troubleshooting fault code P1278 on MX-equipped trucks. Technicians performing emissions diagnostics or addressing torque imbalance complaints will find the structured step-by-step procedures essential for efficient fault isolation and resolution.
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