Optima L4-2.4L (2001)
Oxygen Sensor: Customer Interest
Engine Controls - False MIL ON/DTC P0139
VOLUME
3
GROUP
Engine
NUMBER
008
MODEL
Optima
DATE
October 2002
SUBJECT
Optima P0139 Logic
Some 2001 and 2002 model year Optimas equipped with 2.4 liter 4 cylinder engines may experience malfunction indicator light (MIL) illumination with
a DTC of P0139, indicating rear oxygen sensor rationality malfunction.
The OBDII system relating to the rationality check of the rear oxygen sensor included thresholds that were too severe for normal operation.
Consequently, in certain driving conditions, the system's evaluation of the functionality of the rear oxygen sensor could signal a malfunction of the rear
oxygen sensor when a malfunction does not exist. As a result, a false MIL would be set.
To prevent false MIL illumination, the PCM logic related to rear oxygen sensor rationality check was improved from 2003MY production.
For 2001 MY and 2002MY vehicles that experience false MIL, field fix software has been made available to reprogram the PCM.
Use the procedures in this bulletin for reprogramming the PCM.
REPAIR PROCEDURE:
1.
Connect the reprogramming adapter to the Hi-Scan Pro as shown.
2.
Connect the black Optima 10 pin check connector cable (labeled ECU) to the reprogramming adapter.
