A slight pressure in the exhaust system is normal, but excessive exhaust back pressure seriously affects engine operation. Causes of high exhaust back pressure are dents/obstructions in the exhaust pipe or a plugged three-way catalytic converter/muffler.

1. Remove the oxygen sensor.
2. Connect the gage bar tool kit SA9127E 0-60 in H2O.
3. With the engine at normal operation temperature, observe the exhaust back pressure at constant 4,000 RPM for 5 seconds.
4. Back pressure must be less than 20.13 in H2O (5.0 kPa).

Important: If the exhaust pressure exceeds specification, inspect for dents/obstructions. It may be necessary to disconnect the muffler or the pipe before or behind the converter and repeat the test.

5. Replace the damaged or defective parts.
6. Remove the test equipment.

Notice: Refer to Fastener Notice in the Preface section.

Important: Use non-silicon anti-seize compound on the threads. It may be necessary to use a scan tool to delete any codes set while performing the pressure test.

7. Install the oxygen sensor and tighten.

Tighten
Tighten the oxygen sensor to 45 N·m (33 lb ft).