PACCAR MX (2004 Emissions) Fault Code: P2199 Inlet Air Temperature Before Compressor – Data Erratic, Intermittent or Incorrect, at Ignition On

PACCAR MX (2004 Emissions) Fault Code: P2199 Inlet Air Temperature Before Compressor – Data Erratic, Intermittent or Incorrect, at Ignition On

SET CONDITIONS:
The PCI ECU (D420) detects that the measured temperature reading of the humidity sensor differs more than 3°C [5.4°F] from the average of other temperature sensor readings on the engine for more than 5 seconds (after the ignition has been keyed off for at least 8 hours).

DIAGNOSTIC CONDITION:
This diagnostic runs:
1. When the ignition has been keyed off continuously for at least 8 hours
2. When the difference between the coolant temperature and ambient temperature is less than 15°C [59°F]
3. When the ambient temperature is more than -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:
Humidity sensor deviation

ADDITIONAL INFORMATION:
1. For this diagnostic, the temperature reading of the humidity sensor is compared with an average of other temperature sensors on the engine after the ignition has been keyed off for at least 8 hours.

2. The humidity sensor (F852) is a smart sensor that communicates with the PCI ECU via E-CAN. The sensor measures the following three properties of the drawn in precompressor (VTG turbo charger) air in the inlet air pipe:
– Relative humidity
– Pressure
– Temperature