PACCAR MX (2004 Emissions) Fault Code: P1708 Lambda – Data Valid but Too High

PACCAR MX (2004 Emissions) Fault Code: P1708 Lambda – Data Valid but Too High

SET CONDITIONS:
The PCI ECU (D420) detects that the oxygen concentration measured by the lambda sensor is higher than the oxygen concentration measured by the NOx sensor before catalyst for more than 40 seconds.

DIAGNOSTIC CONDITION:
This diagnostic runs:
1. When the engine speed is between 950 and 2000 rpm and
2. When the coolant temperature is above 50°C [122°F] and
3. The lambda sensor (F834) is in operating mode
4. The NOx sensor before catalyst (F844) is in operating mode
5. The engine mode is SCR high efficiency or standard or protection

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

POSSIBLE CAUSES:
1. Lambda sensor deviation
2. NOx sensor before catalyst deviation

ADDITIONAL INFORMATION:
1. The PCI ECU uses the oxygen concentration in the exhaust measured by the lambda sensor (F834) to determine the air/fuel ratio of the combustion process.

2. The oxygen concentration in the exhaust measured by the lambda sensor is compared with the oxygen concentration measured by the NOx sensor before catalyst (F844).