Code 13 - Oxygen (O2) Sensor Open Circuit

Code No. 13 will set if:

• Engine is at normal operating temperature.
• Engines has operated at least 2 minutes.
• O2 sensor voltage steady .35-.55 volts for more than one minute.
• Throttle angle greater than 7 percent.
• All conditions above must be met for approximately 60 seconds.
  NOTE: Test numbers refer to test numbers on diagnostic chart.
  1. Grounding diagnostic terminal with engine running allows the ECM to confirm either "open or closed loop" by using the "CHECK ENGINE" light.
  2. This indicates a lean exhaust. If all components are okay, the ECM will note the lean condition and turn the "CHECK ENGINE" light off for at least 30 seconds after engine starts and then flash "open loop". Light may remain off for a longer period of time prior to flashing "open loop".

Fig 1: Flow Chart - Code 13, Open Oxygen Sensor Circuit

Courtesy of ISUZU MOTOR CO.