GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 1997 🢒 LeSabre 🢒 Engine 🢒 Engine Controls - 3.8L 🢒 Restricted Exhaust System Check

Restricted Exhaust System Check

Step

Action

Value(s)

Yes

No

1

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

--

Go to Step 2

Go to the Powertrain On Board Diagnostic (OBD) System Check

2
  1. Remove HO2S 1 Refer to Refer to Heated Oxygen Sensor Replacement .
  2. In place of HO2S 1, install a J 35314-A Exhaust Back Pressure Tester.
  3. Start the engine.
  4. With the engine idling at normal operating temperature and the vehicle in park, observe the exhaust system back pressure reading on the gage.

Does the reading exceed the specified value?

8.6 kPa (1.25 psi)

Go to Step 4

Go to Step 3

3
  1. Leave the vehicle in park.
  2. With the exhaust back pressure tester or equivalent in place of HO2S 1, increase engine speed to 2000 rpm.
  3. Observe the exhaust system back pressure reading on the gage.

Does the reading exceed the specified value?

20.7 kPa (3 psi)

Go to Step 4

System OK

4
  1. Reinstall HO2S 1.
  2. Remove HO2S 2.
  3. In place of HO2S, install a J 35314-A Exhaust Back Pressure Tester.
  4. Engine at normal operating temperature.
  5. Leave the vehicle in park.
  6. Increase engine speed to 2000 rpm.
  7. Observe the exhaust system back pressure reading on the gage.

Does the reading exceed the specified value?

20.7 kPa (3 psi)

Go to Step 5

Go to Step 6

5

Locate and repair the restriction in the exhaust system past the three way catalytic converter. Possible malfunctions include:

    • Collapsed pipe.
    • Heat distress.
    • Internal muffler failure.

Refer to Exhaust System .

Is action complete?

--

Go to Step 7

--

6

Replace the three way catalytic converter. Refer to Exhaust System .

Is action complete?

--

Go to Step 7

--

7
  1. Remove HO2S 1.
  2. In place of HO2S 1, install a J 35314-A Exhaust Back Pressure Tester.
  3. Leave the vehicle in park.
  4. Engine idling at normal operating temperature
  5. Observe the exhaust system back pressure reading on the gage.

Does the reading exceed the specified value?

8.6 kPa (1.25 psi)

Go to Step 4

Go to Step 8

8
  1. Leave the vehicle in park.
  2. With the exhaust back pressure tester in place of HO2S 1, increase engine speed to 2000 rpm
  3. Observe the exhaust system back pressure reading on the gage.

Does the reading exceed the specified value?

20.7 kPa (3 psi)

Go to Step 5

System OK