PACCAR MX P040D is the fault-code chapter of the 2013 PACCAR MX Diagnostic Service Manual covering EGR temperature voltage too high, or a short circuit to supply on ECU D420 pin C9. It is a one-trip MIL code with three drive cycle recovery, and the diagnostic runs continuously while the ignition is on. The sensor is fitted after the EGR cooler, feeding gas density correction, high-temperature EGR valve closure and cooler performance monitoring.
Document details at a glance
| Brand | PACCAR |
|---|---|
| Model coverage | PACCAR MX engines, EPA 2013 emissions level |
| System group | DTCs, MX Engines EPA2013 |
| Source publication | 2013 PACCAR MX Diagnostic Service Manual, pages 272 to 275 |
| Pages | 4 |
| File size | 0.4 MB |
| Format | |
| Language | English |
What the PACCAR MX P040D chapter covers
- Set condition: the PCI ECU D420 sees circuit output voltage greater than 4.9 V
- Reset condition: inactive immediately after the diagnostic runs and passes
- Named components: D420 as the PCI ECU and F749 as the EGR temperature sensor
- Pin functions with C9 as signal and C31 as ground
- Resistance values for sensor F749 rising from 97.7 Ω at 0°C to 195.5 Ω at 250°C
- A 5 V circuit check at the harness connector with the ignition keyed on
Diagnostic step sequence and verification
Inside PACCAR MX P040D the procedure runs as follows. Four steps mirror the low-voltage chapter but run the substitution in the opposite direction. Disconnect the temperature sensor with the key off, then read errors in DAVIE: a change to P040C condemns the sensor. If the high-voltage code persists you disconnect the harness at the PCI and read again, where a change condemns the engine harness. A code that survives both tests is a possible PCI failure and goes to the Engine Support Center.
Trucks and engines it applies to
The chapter applies to EPA 2013 PACCAR MX engines with cooled EGR in Kenworth and Peterbilt trucks, using a breakout harness rather than back probing, which PACCAR does not recommend. Model programmes and dealer support for these engines are listed on the PACCAR corporate site.
Who needs the PACCAR MX P040D chapter
Anyone diagnosing an EGR temperature complaint should read this chapter beside its low-voltage twin, because the pair together show which side of the circuit failed.
The complete PDF of the PACCAR MX P040D chapter is filed in the DiagTechPro manuals library, where a free account is required to download it alongside the rest of the MX Engines EPA2013 fault-code set.
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