CODE 13 (Open O2 Sensor Circuit)
- Ground test terminal at ALDL and connect dwell meter to feedback solenoid (6-cyl. scale). With engine idling, disconnect and ground O2 sensor connector to ECM. See Fig 1
. If dwell is greater than 10 degrees after 30 seconds, go to step 2). If dwell is less than 10 degrees after 30 seconds, O2 sensor or connection is faulty.
- Connect jumper between ECM terminals No. 3 and 20. If dwell is greater than 10 degrees after 30 seconds, go to step 3). If dwell is less than 10 degrees after 30 seconds, repair open from O2 sensor to ECM.
- Check ground at ECM terminal No. 20. If okay, ECM or connection are faulty.
Courtesy of GENERAL MOTORS CORP.