LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Jeep >> 2007 >> Commander Overland, 4WD >> Repair and Diagnosis >> Engine Performance >> System >> DTCS P0123 To P0174 >> P0138-O2 Sensor 1/2 Circuit High >> Possible Causes
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Possible Causes

Possible Causes 
(K141) O2 1/2 SIGNAL CIRCUIT SHORTED TO VOLTAGE
(K904) O2 RETURN DOWNSTREAM CIRCUIT SHORTED TO VOLTAGE
(K141) O2 1/2 SENSOR SIGNAL CIRCUIT OPEN
(K904) O2 RETURN DOWNSTREAM CIRCUIT OPEN
1/2 O2 SENSOR
POWERTRAIN CONTROL MODULE (PCM)

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Refer to PRE-DIAGNOSTIC TROUBLESHOOTING PROCEDURE .