GM Service Manual Online
For 1990-2009 cars only

Object Number: 16621  Size: SH
(1)Back Pressure Gauge
(2)Heated Oxygen Sensor (HO2S)
(3)Exhaust Pipe

Step

Action

Value(s)

Yes

No

1

Was the Powertrain On-Board Diagnostic (OBD) System Check performed?

--

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

2

  1. Carefully remove the Heated Oxygen Sensor (HO2S).
  2. Install the exhaust backpressure tester J 35314-A in place of the HO2S.
  3. Start the engine and idle.

Is the reading greater than the specified value?

8.6 kPa (1.25  psi)

Go to Step 4

Go to Step 3

3

  1. Increase the engine speed to the specified value.
  2. Observe the backpressure gauge.

Does the reading exceed the specified value?

2000 RPM

20.7 kPa (3 psi)

Go to Step 4

Go to Step 6

4

  1. Check the exhaust system for a collapsed pipe, internal muffler failure, or any kind of heat distress.
  2. If a problem is found, repair as necessary.

Was a problem found?

--

Go to Step 6

Go to Step 5

5

Replace the catalytic converter. Refer to Engine Controls or Exhaust of the appropriate service manual.

Is the action complete?

--

Go to Step 6

--

6

Operate the vehicle within the conditions under which the original symptom was noted.

Does the system now operate properly?

--

System OK

Go to Step 2