Nissan B08A0-4L700 Three Way Catalyst Converter

Here are the steps: Connect a vacuum gauge to an intake manifold vacuum source. Warm the engine to operating temperature, place the transaxle in park, and apply the parking brake. Note and record the vacuum reading at idle. Open the throttle until the engine speed is about 2000 rpm. Release the throttle quickly and record the vacuum reading. Perform the test three more times, recording the reading after each test. If the reading after the fourth test is more than one in-Hg lower than the reading recorded at idle, it may indicate a plugged or restricted catalytic converter, muffler, or exhaust pipes.