PACCAR MX (2004 Emissions) Fault Code: P170C NOx Sensor before Catalyst Response – Data Erratic, Intermittent or Incorrect, During Overrun

Description

PACCAR MX (2004 Emissions) Fault Code: P170C NOx Sensor before Catalyst Response – Data Erratic, Intermittent or Incorrect, During Overrun

SET CONDITIONS:
The PCI ECU (D420) detects that the measured engine NOx emissions differ too much from the expected engine NOx emissions after 3 seconds during coasting (fuel injection cutoff).

DIAGNOSTIC CONDITION:
This diagnostic runs:
1. When the engine speed is above 1200 rpm and
2. During coasting (no fuel injection) and
3. When the coolant temperature is above 50°C [122°F] and
4. The NOx sensor before catalyst (F844) is in the operating mode

CORRESPONDING OBD READINESS MONITOR:
Exhaust gas sensors monitor

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 following conditions:
– Corresponding readiness monitor displays ‘Ready’
– Diagnostic conditions are met
– Set conditions are met
3. Did the DTC come back? (Can be pending, inactive or active)
– No, repair successful
– Yes, repair unsuccessful

POSSIBLE CAUSES:
1. Faulty fuel system
2. NOx sensor before catalyst deviation

ADDITIONAL INFORMATION:
1. The measured engine NOx emission is compared with the expected engine NOx emissions during coasting (fuel injection cutoff).
2. The engine NOx emissions are measured by the NOx sensor before catalyst (F844).