GM Service Manual Online
For 1990-2009 cars only

Object Number: 198702  Size: SF
(1)Exhaust Manifold Heat Shield
(2)J 35314 Exhaust Back Pressure Tester
(3)HO2S 1 Exhaust Manifold Fitting

Step

Action

Value(s)

Yes

No

1

Did you perform the Powertrain On-Board Diagnostic (OBD) System Check?

--

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

2

  1. Remove the HO2S 1 from the exhaust manifold.
  2. Install the J 35314-A exhaust back pressure tester or an equivalent in the exhaust manifold HO2S 1 fitting.

Is the action complete?

--

Go to Step 3

--

3

Important: Place the transmission in Neutral when checking exhaust system backpressure. Accurate backpressure readings can not be obtained unless the transmission remains in Neutral for all tests.

  1. Start the engine.
  2. Observe the exhaust system back pressure reading on the gauge with the engine idling in Neutral. The gauge reading should not exceed the specified value.

Did the reading exceed the specified value?

8.6 kPa (1.25 psi)

Go to Step 5

Go to Step 4

4

  1. Increase the engine speed to 2,500 RPM.
  2. Observe the back pressure reading on the gauge. The gauge reading should not exceed the specified value.

Did the reading exceed the specified value?

8.6 kPa (1.25 psi)

Go to Step 5

Go to Step 7

5

  1. Check the entire exhaust system for a collapsed pipe, heat distress, or possible internal muffler failure.
  2. Replace any malfunctioning component.

Did any component require replacement?

--

Go to Step 7

Go to Step 6

6

Replace the catalytic converter. Refer to Front Pipe Replacement in Engine Exhaust.

Is the action complete?

--

Go to Step 7

--

7

  1. Idle the engine until normal operating temperature is reached.
  2. Check for DTCs.

Are any DTCs displayed that have not been diagnosed?

--

Go to the applicable DTC table

System OK