Nissan 208A1-9S225 Three Way Catalyst Converter

Whenever the vehicle is raised for underbody servicing, it's important to check the converter for leaks, corrosion, dents, and other damage. Also, check the welds/flange bolts that attach the front and rear ends of the converter to the exhaust system. If damage is found, the converter should be replaced.

To check for a restricted converter, you can use a vacuum gauge to diagnose the effect of a blocked exhaust on intake vacuum. Connect a vacuum gauge to an intake manifold vacuum source, warm the engine to operating temperature, and record the vacuum readings at idle and at 2000 rpm. 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.