GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

1

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

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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 exhaust back pressure tester J 35314-A Exhaust Back Pressure Tester and J 35314-10 adapter in place of the HO2S 1.

Is the action complete?

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Go to Step 3

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3

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

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

Does the reading exceed the specified value?

8.6 kPa (1.25 psi)

Go to Step 5

Go to Step 4

4

Increase the engine speed to 2500 RPM and observe back pressure reading on the gauge. The reading should not exceed the specified value.

Does 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 component found malfunctioning.

Did any component require replacement?

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Go to Step 7

Go to Step 6

6

Replace the catalytic converter.

Is the action complete?

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Go to Step 7

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7

  1. Allow engine to idle until normal operating temperature is reached.
  2. Check if any DTCs are set.

Are any DTCs displayed that have not been diagnosed?

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Go to the applicable DTC table

System OK