Test Number 1)

This tests if problem still exists. Vehicle cannot enter "closed loop" mode if O2 sensor circuit is open. Code 13 indicates an open in O2 sensor circuit. Code will set if:

• Engine is at normal operating temperature.
• Neither Code 21 nor Code 22 is stored.
• O2 sensor voltage is constant within a specified range (.34-.55 volt).
• Throttle angle is greater than idle.
• A precalibrated amount of time has elapsed since start-up.
• All conditions have existed for a precalibrated amount of time.