This PACCAR P1235 turbo speed diagnostic guide covers fault detection and repair procedures for PACCAR MX Europe diesel engines equipped with EPA 2004 emissions standards. Published by PACCAR on behalf of truck service technicians, the document explains the conditions that trigger the P1235 code, diagnostic workflow, and verification methods for turbo system repairs.
Document details and specifications — PACCAR P1235 turbo
| Brand | PACCAR |
| Model coverage | MX EPA 2004, MX EPA 2013 |
| System/Group | DTCs / MX Europe Engines (EPA 2004) |
| Publication number | M033264 |
| Year/Revision | 17 August 2017 |
| Pages | 2 |
| File size | 0.1 MB |
| Format | |
| Language | English |
Table of contents
- Set conditions
- Diagnostic condition
- Corresponding OBD readiness monitor
- Reset condition
- Repair verification
- Possible cause
- Additional information
Applies to these models
This diagnostic applies to PACCAR MX engines with EPA 2004 and EPA 2013 emission standards. The PACCAR P1235 turbo speed code is triggered when the PCI ECU (D420) detects that measured turbo speed differs too much from expected turbo speed for more than 120 seconds during steady-load engine operation at coolant temperatures above 50°C (122°F). For official PACCAR resources and engine specifications, visit PACCAR official website.
Who needs this P1235 turbo speed guide
Diesel truck mechanics and workshop owners maintaining PACCAR MX-equipped vehicles need this P1235 turbo speed resource to accurately diagnose turbo faults and boost pressure sensor issues. The guide provides step-by-step repair verification and pinpoints the turbo speed sensor (F683) and boost pressure sensor as the primary fault sources.
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