Possible Cause

NOTE:  The causes shown may not be a complete list of all potential problems, and it is possible that there may be other causes.

• Rear A/F sensor (bank 1, sensor 1) AFVB1 line short to ground
• Rear A/F sensor (bank 1, sensor 1) AFVB1 line short to rear A/F sensor (bank 1, sensor 1) AFCB1 line