PACCAR MX (2004 Emissions) Fault Code: P1706 Lambda Response Rate – Too High

PACCAR MX (2004 Emissions) Fault Code: P1706 Lambda Response Rate – Too High

SET CONDITIONS:
The PCI ECU (D420) detects that the measured oxygen concentration in the exhaust differs too much from the expected oxygen concentration.

DIAGNOSTIC CONDITION:
This diagnostic runs:
1. When the engine speed is between 1200 and 2100 rpm and
2. The coolant temperature is above 50°C [122°F] and
3. The lambda sensor (F834) is in the operating mode (if applicable).
4. The engine mode is DOC heating or DPF regeneration or SCR heating or SCR high efficiency or standard or protection

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. Lambda sensor deviation (if equipped with lambda sensor)
2. NOx sensor before catalyst deviation (only if NOT equipped with lambda sensor)

ADDITIONAL INFORMATION:
IMPORTANT: Depending on the production date of the vehicle, either the lambda sensor (F834) or the NOx sensor before catalyst (F844) is used to determine the oxygen concentration in the exhaust gas.

Typically, high value air/fuel ratio indicates high oxygen concentration in the exhaust system.