When Monitored

With the engine running, before the O2 system enters closed loop operation (Cold test on startup) and during closed loop operation.
- 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. The PCM will run a Cold test, performed at power down (ignition off) to identify the specific circuit with the failure.