PACCAR MX P0069 is the fault code chapter the 2013 PACCAR MX Diagnostic Service Manual publishes for “Boost pressure – Data erratic, intermittent, or incorrect at ignition on”. The 8-page PDF is PACCAR’s own troubleshooting write-up for EPA2013 MX engines, reproduced exactly as the factory issued it.
Document details and coverage
| Brand | PACCAR |
|---|---|
| Group | DTCs / MX Engines (EPA2013) |
| Fault code | P0069 |
| Fault code information | 2 trip MIL, 3 drive cycle recovery, freeze frame type Comprehensive |
| Source manual | 2013 PACCAR MX Diagnostic Service Manual |
| Pages | 8 |
| File size | 0.6 MB |
| Format | |
| Language | English |
What sets PACCAR MX P0069 active
The diagnostic runs when the ignition is keyed on with no engine start and the ambient temperature is above -20°C [-4°F]. The PCI ECU (D420) sets the code when the measured boost pressure differs by more than 0.17 bar [2.5 psi] from the average of the other pressure sensor readings on the engine for more than 5 seconds. To validate the repair the ignition is keyed on with no engine start and left for 10 seconds so the system powers up and the diagnostics run.
Component and wiring checks
- PCI ECU connector D420.A pins A39 (ground), A47 (power supply) and A51 (boost pressure signal) to sensor connector F802 pins 4, 2 and 1
- The boost pressure sensor cannot be assessed with a multimeter or an oscilloscope
- The sensor is monitored and tested with DAVIE, followed by the wiring check
Possible causes and repair notes
- A boost pressure reading that deviates from the other engine pressure sensors
- Damaged, corroded or wet connector pins at the sensor or the PCI ECU
- Open or shorted wiring between the sensor and the ECU
The boost pressure sensor (F802) sits in the inlet manifold near cylinder 1, and the manual explains how its reading feeds the smoke limit, the calculated soot and NOx emissions, the exhaust gas mass flow used for DEF dosing by the EAS-3 system, and the calculated temperatures after the compressor and before the turbine. Company and product background is on the official PACCAR website.
Who needs this PACCAR MX P0069 chapter
Heavy-duty diesel technicians and fleet shops reach for PACCAR MX P0069 when the code lands on a DAVIE scan and the repair has to follow the factory sequence instead of guesswork.
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