PACCAR MX P040B is the fault-code chapter of the 2013 PACCAR MX Diagnostic Service Manual covering EGR temperature data that is erratic, intermittent or incorrect at ignition on. It is a two-trip MIL code with three drive cycle recovery and a comprehensive freeze frame type. EGR gas flow temperature is measured after the EGR cooler, and the reading corrects EGR flow, closes the EGR valve on high temperature and monitors 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 264 to 267 |
| Pages | 4 |
| File size | 0.4 MB |
| Format | |
| Language | English |
What the PACCAR MX P040B chapter covers
- Diagnostic conditions: ignition off at least 8 hours, coolant to ambient difference under 15°C, ambient above -20°C
- Set condition: the sensor differs by more than 3°C from the average of other temperature sensors for over 5 seconds
- The soak procedure needed to rerun the check: 8 to 10 hours off, key on 10 seconds, then a 2 minute idle
- Pin functions with D420 C9 as the EGR temperature signal and C31 as ground
- Sensor resistance from 97.7 Ω at 0°C up to 195.5 Ω at 250°C, plus a 5 V key-on circuit check
- Possible cause given simply as EGR temperature sensor deviation
Diagnostic step sequence and verification
Inside PACCAR MX P040B the procedure runs as follows. Four steps follow. A visual inspection for bent, broken or corroded pins comes first, then electrical checks on supply and signal voltages and cable continuity. Values outside limits send you to replace the smart sensor, after which DAVIE rechecks for active faults. Anything still live goes to the PACCAR Engine Support Call Center on 1-800-477-0251.
Trucks and engines it applies to
The chapter covers EPA 2013 PACCAR MX engines with cooled EGR in Kenworth and Peterbilt trucks, and the soak requirement means the truck must sit overnight before retesting. Model programmes and dealer support for these engines are listed on the PACCAR corporate site.
Who needs the PACCAR MX P040B chapter
Shops that keep getting the code back after a sensor swap need this chapter, because the fault is a comparison against other sensors and only clears on a soaked engine.
The complete PDF of the PACCAR MX P040B 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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