PACCAR MX (2004 Emissions) Fault Code: P171E Air Mass Flow – Data Valid but Too High

PACCAR MX (2004 Emissions) Fault Code: P171E Air Mass Flow – Data Valid but Too High

SET CONDITIONS:
The PCI ECU (D420) detects that, at a boost pressure, the calculated inlet air mass flow is lower than the expected inlet air mass flow for more than 50 seconds.

DIAGNOSTIC CONDITION:
This diagnostic runs:
1. When the engine speed is between 1000 and 1850 rpm and
2. When the engine is running at a steady load and
3. When the coolant temperature is above 50°C [122°F] and
4. The engine mode is SCR high efficiency or standard

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

POSSIBLE CAUSES:
1. Leaking inlet air system
2. Boost pressure sensor deviation
3. Turbocharger failure

ADDITIONAL INFORMATION:
1. The engine inlet air mass flow is calculated by measuring the engine speed, fuel injection quantity, coolant temperature, boost pressure, boost temperature, and pressure before the turbine.

2. The engine speed and fuel injection quantity are calculated by the PCI ECU. Other sensors involved are the coolant temperature sensor (F566), boost pressure sensor (F802), boost temperature sensor (F804), and pressure sensor before turbine (F826).