This document is the 2013 PACCAR MX Diagnostic Service Manual covering PACCAR MX ambient pressure and internal ECU sensor diagnostics. Published by PACCAR for MX-series engines compliant with 2013 EPA emissions standards, it provides technicians with fault code definitions, component descriptions, and structured troubleshooting procedures for P2226 (Internal ECU Ambient Pressure – Data Erratic, Intermittent, or Incorrect at Ignition On).
The manual addresses the atmospheric pressure sensor and temperature sensor located within the PCI electronic control unit, explaining how these internal sensors affect engine torque delivery at high altitudes and ECU thermal monitoring.
Document details and specifications — PACCAR MX ambient
| Brand | PACCAR |
| Model coverage | MX series engines |
| System/Group | DTCs / MX Engines (EPA2013) |
| Publication number | 2013 PACCAR MX Diagnostic Service Manual, page 250–252 |
| Year/Revision | 2013 |
| Pages | 3 |
| File size | 0.5 MB |
| Format | |
| Language | English |
Table of contents
- Code number P2226 and fault code description
- Fault code information (trip count, MIL behavior, freeze frame type)
- Description of internal ECU components (atmospheric pressure sensor, temperature sensor)
- Effect on engine system and torque management
- Injector calibration codes and reprogramming requirements
- Location of components
- Diagnostic conditions and running criteria
- Set condition and reset condition procedures
- Possible causes and pressure sensor comparison data
- Additional information on non-serviceable internal sensors
- Step-by-step diagnostic troubleshooting (Steps 1–4)
- Verification drive cycle and error clearance procedure
Applies to these models
This PACCAR MX ambient pressure manual applies to 2013-compliant PACCAR MX-series diesel engines equipped with the PCI electronic control unit. It covers both naturally aspirated and turbocharged configurations where internal atmospheric pressure sensing is integrated into the engine control module. For official PACCAR technical support and parts information, visit PACCAR official website.
Who needs this PACCAR MX ambient pressure manual
Heavy-duty diesel mechanics and workshop owners servicing PACCAR MX engines will rely on this MX ambient pressure guide when diagnosing fault code P2226, especially when dealing with altitude compensation issues, ECU sensor drift, or after replacing fuel injectors or the control unit itself. Fleet maintenance teams troubleshooting erratic ambient pressure readings during ignition-on diagnostics depend on the structured approach outlined here.
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