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

1. Remove the front HO2S on the side of the engine that is suspected of being restricted. Refer to Heated Oxygen Sensor Replacement - Bank 1 or Heated Oxygen Sensor Replacement - Bank 2 .
2. Install the Exhaust Back Pressure tester J 35314-A in place of the HO2S.
3. Idle the engine at normal operating temperature.
4. Observe the exhaust system back pressure reading on the gauge.

Does the reading exceed the specified value?

8.6 kPa (1.25 psi)

Go to Step 4

Go to Step 3

1. The Exhaust Backpressure Gauge still installed.
2. Increase engine speed to 2000 RPM.
3. Observe the exhaust system back pressure reading on the gauge.

Does the reading exceed the specified value?

20.7 kPa (3 psi)

Go to Step 4

Go to Symptoms

1. Turn OFF the engine.
2. Re-install the front HO2S.
3. Remove the rear HO2S on the side of the engine that is suspected of being restricted. Refer to Heated Oxygen Sensor Replacement - Bank 1 or Heated Oxygen Sensor Replacement - Bank 2 .
4. Install the Exhaust Back Pressure tester J 35314-A in place of the HO2S.
5. Idle the engine.
6. Increase the engine speed to 2000 RPM.
7. Observe the exhaust system back pressure reading on the gauge.

Does the reading exceed the specified value?

20.7 kPa (3 psi)

Go to Step 5

Go to Step 6

Repair the restriction in the exhaust system after the Catalytic Converter. Inspect the exhaust system for the following:

Is the action completed?

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System OK

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Replace Catalytic Converter. Refer to Oxidation Catalytic Converter Replacement in Engine Exhaust.

Is the action completed?

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System OK

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