GM Service Manual Online
For 1990-2009 cars only

Object Number: 260742  Size: SH

Restricted Exhaust System Check

Step

Action

Values

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 heated oxygen sensor (HO2S 1) from the exhaust manifold.
  2. Install the J 35314-A exhaust back pressure tester and the J 35314-10 adapter in place of the HO2S 1.

Is the action complete?

--

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 cannot be obtained unless the vehicle remains in Park or Neutral for all of the 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 the 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, any heat distress, or an 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.

Is the action complete?

--

Go to Step 7

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7

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

Are any DTCs displayed that have not been diagnosed?

--

Go to Diagnostic Trouble Code (DTC) List

System OK