PACCAR MX P040C is the fault-code chapter of the 2013 PACCAR MX Diagnostic Service Manual covering EGR temperature voltage too low, or a short circuit to ground on ECU D420 pin C9. PACCAR lists it as a two-trip MIL code with three drive cycle recovery and a generic freeze frame type. The EGR temperature sensor sits after the EGR cooler, correcting gas flow, closing the EGR valve on high temperature and monitoring cooler performance.
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 268 to 271 |
| Pages | 4 |
| File size | 0.4 MB |
| Format | |
| Language | English |
What the PACCAR MX P040C chapter covers
- Set condition: the PCI detects sensor output voltage below 0.05 V
- Reset condition: the code goes inactive immediately once the diagnostic runs and passes
- Pin functions with D420 C9 carrying the signal and C31 the ground
- Component check resistance for sensor F749 from 97.7 Ω at 0°C to 195.5 Ω at 250°C
- ECU circuit check expecting 5 V at the harness connector with the ignition keyed on
- Possible causes listed as faulty wiring, a faulty connector or a faulty sensor
Diagnostic step sequence and verification
Inside PACCAR MX P040C the procedure runs as follows. The substitution logic makes this chapter useful. After the visual inspection you disconnect the sensor and read errors in DAVIE: a flip to P040D condemns the sensor. If the code holds, disconnect the harness at the PCI and read again, where a flip condemns the engine harness. A code that will not move points at the PCI and goes to the Engine Support Call Center on 1-800-477-0251.
Trucks and engines it applies to
The procedure covers EPA 2013 PACCAR MX engines with cooled EGR in Kenworth and Peterbilt trucks, and warns that disconnecting EAS connectors during troubleshooting will throw multiple extra errors. Model programmes and dealer support for these engines are listed on the PACCAR corporate site.
Who needs the PACCAR MX P040C chapter
Technicians who want to separate a shorted wire from a dead sensor use this chapter, because the code-flip test does the job with a connector and a scan tool.
The complete PDF of the PACCAR MX P040C 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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