Catalytic Converter: Testing and Inspection

Back Pressure Test:

Proper diagnosis for a restricted exhaust system is essential before any components are replaced. The following procedure may be used for diagnosis:

CHECK AT 02 SENSOR:

1. Carefully remove O2 sensor.

2. Install Exhaust Backpressure Tester in place of 02 sensor.

3. After completing test described below, be sure to coat threads of O2 sensor with anti-seize compound prior to re-installation.

DIAGNOSIS:

1. With the engine at normal operating temperature, observe the exhaust system backpressure reading on the gauge. Reading should not exceed 7.8 kPa (1.13 psi) for Federal and 9.5 kPa (1.42 psi) for California.

2. Increase engine speed to 2000 rpm and observe gauge. Reading should not exceed 14.6 kPa (2.11 psi) for Federal and 11.8 kPa (1.71 psi) for California.

3. If the backpressure at either speed exceeds specification, a restricted exhaust system is indicated.

4. Inspect the entire exhaust system for a collapsed pipe, heat distress, or possible internal muffler failure.

5. If there are no obvious reasons for the excessive backpressure, the catalytic converter is suspected to be restricted and should be replaced.