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 pre-catalyst HO2S. Refer to Heated Oxygen Sensor Replacement .
2. Install the J 35314-A Exhaust Back-Pressure Tester, or an equivalent, in place of the HO2S.
3. Start the engine.
4. Increase and monitor the engine speed at 2500 RPM.
5. Observe the exhaust system back-pressure reading on the gage.

Does the reading exceed the specified value?

9 kPa (1.25 psi)

Go to Step 3

Go to Step 6

1. Turn the engine off and place the ignition in the LOCK position.
2. Remove the J 35314-A .
3. Install the pre-catalyst HO2S. Refer to Heated Oxygen Sensor Replacement .
4. Remove the post-catalyst HO2S. Refer to Heated Oxygen Sensor Replacement .
5. Install the J 35314-A in place of the post-catalyst HO2S sensor.
6. Start the engine.
7. Increase and monitor the engine speed at 2500 RPM.
8. Observe the exhaust system back pressure reading on the gage.

Does reading exceed the specified value?

9 kPa (1.25 psi)

Go to Step 4

Go to Step 5

Inspect the exhaust system for the following conditions:

Did you find and correct the condition?

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Go to Step 6

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Replace the catalytic converter. Refer to Catalytic Converter Replacement in Engine Exhaust.

Did you find and correct the condition?

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Go to Step 6

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1. Remove the J 35314-A .
2. Install the pre- or post-catalyst HO2S sensor. Refer to Heated Oxygen Sensor Replacement .
3. Clear any codes.
4. Road test the vehicle in order to verify the repair.

Did you correct the condition?

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System OK

Go to Step 1