PACCAR MX (2004 Emissions) Fault Code: P2226 Internal ECU Ambient Pressure – Data Erratic, Intermittent or Incorrect, at Ignition On

PACCAR MX (2004 Emissions) Fault Code: P2226 Internal ECU Ambient Pressure – Data Erratic, Intermittent or Incorrect, at Ignition On

SET CONDITIONS:
The PCI ECU (D420) detects that the measured ambient pressure differs by more than 0.06 bar [0.87 psi] from the average readings of other pressure sensors in the engine/aftertreatment system for more than 5 seconds.

DIAGNOSTIC CONDITION:
This diagnostic runs:
1. When the ignition is on and the engine is not running and
2. When ambient temperature is above -20°C [-4°F]

CORRESPONDING OBD READINESS MONITOR:
None

RESET CONDITION:
This DTC changes to inactive when the fault is no longer detected.

REPAIR VERIFICATION:
1. Clear all DTCs.
2. Test drive or operate the vehicle to meet the diagnostic conditions and set conditions.
3. Did the DTC come back? (Can be pending, inactive or active)
– No, repair successful
– Yes, repair unsuccessful

POSSIBLE CAUSES:
Faulty pressure sensor, internally in ECU.

ADDITIONAL INFORMATION:
The PCI ECU has an internal ambient pressure sensor in the housing. The ambient pressure sensor is not serviceable.

For this diagnostic, the ambient pressure sensor reading is compared with the average readings from the pre-compressor pressure (humidity sensor (F852)), boost pressure sensor (F802) and DPF pressure sensor (F837).