PACCAR MX (2004 Emissions) Fault Code: P1139 Lambda Sensor Calibration – Malfunction

PACCAR MX (2004 Emissions) Fault Code: P1139 Lambda Sensor Calibration – Malfunction

SET CONDITIONS:
The PCI ECU (D420) detects that the calibration phase of the lambda sensor has been completed unsuccessfully after several attempts.

DIAGNOSTIC CONDITION:
This diagnostic runs when the lambda sensor operating status is calibration.

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

POSSIBLE CAUSES:
Faulty lambda sensor

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. The sensor has an integrated heater to maintain a sensor operating temperature of approximately 750?C [1382?F].

2. One of the lambda sensor operating statuses is the calibration mode. In calibration mode, an internal comparison is made between the actual and ideal lambda references so necessary signal corrections can be made accordingly.