Code 13, Heated Oxygen Sensor Circuit, Open Circuit: Notes

Heated Oxygen (O2) sensor produces a voltage that varies within a range of about 0.1 volt (lean exhaust) to 1.0 volt (rich exhaust). O2 sensor has a built-in heater that keeps O2 sensor at operating temperature while engine is running. O2 sensor is like an open circuit and produces no voltage when sensor temperature is less than 600°F (316°C), causing an open loop condition.

Code 13 will set if the following conditions are met for at least 30 seconds:

• Engine operating temperature is greater than 158°F (70°C).
• Engine running for at least 2 minutes.
• Engine speed is greater than 260 RPM.
• MAP sensor pressure is greater than 350 mm Hg of vacuum.
• Heated O2 sensor temperature less than 600°F (360°C).
  NOTE: Test numbers refer to test numbers on diagnostic chart.

1. Checks for short to voltage in Yellow/Blue wire or a faulty ECM.
2. Checks for short to ground in Yellow/Blue wire, a faulty ECM or a faulty O2 sensor.