When Monitored

With the engine running, before the O2 system enters closed loop operation (Cold test on startup) and during closed loop operation. When the PCM detects a circuit has fallen outside the allowable range during the Cold test (at startup) or during closed loop operation, a Hot test is initiated. The hot test will be repeated every 20 seconds, as long as the circuit voltage measurements are still out of range. This will continue until the ignition is turned off or until the measurements are in range. The PCM will run a Cold test, performed at power down (ignition off) to identify the specific circuit with the failure.