Test Method

Fig 1: View Of Exhaust System

Courtesy of GENERAL MOTORS CORP.

Remove the oxygen sensor.
Connect the gage bar tool kit SA9127E 0-60 in H2O.
With the engine at normal operation temperature, observe the exhaust back pressure at constant 4,000 RPM for 5 seconds.
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.

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

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.

NOTE: Refer to Fastener Notice in Cautions and Notices.

Install the oxygen sensor and tighten.
Tighten: Tighten the oxygen sensor to 45 N.m (33 lb ft).