For 1990-2009 cars

### Diagnostic Aids

For dual exhaust systems a quick check of exhaust flow will help determine which side of the exhaust system is restricted. The side that has less exhaust flow is the side that will be suspect, and diagnosis should begin there.

### Test Description

The numbers below refer to the step numbers on the diagnostic table.

1. The exhaust system has very low backpressure under normal conditions. If the exhaust system is restricted, a significant increase in exhaust pressure is noticed on the J 35314. Note: Removing the O2S sensor may set a DTC. When finishing this diagnostic table, be sure to clear all codes.

2. This step will isolate the catalytic converter from the remainder of the exhaust system.

3. Confirming that the condition has been fixed is essential. If the symptom still exists and the vehicle has a dual exhaust system, proceed to Step 2 and repeat diagnostic procedure on the opposite exhaust pipe.

Step | Action | Values | Yes | No
--- | --- | --- | --- | ---
1 | Did you verify the customer's complaint? | -- | Go to Step 2 | --
2 | Warning: While engine is operating, the exhaust system will become extremely hot. To prevent burns avoid contacting a hot exhaust system.

1. Perform a complete visual and physical inspection of the exhaust system.
2. Repair or replace any damaged pipes or components that can cause a restriction in the exhaust gas flow.

Did you find and correct a condition?

--

Go to Step 7

Go to Step 3

3 | Is the system equipped with dual exhaust? | -- | Go to Diagnostic Aids | Go to Step 4
4 |

1. Remove the O2S that is in front of and closest to the catalytic converter.
2. Install the J 35314-A in place of the O2S sensor.
3. Start the engine.
4. Observe the exhaust system backpressure reading on the gage.

Does the reading exceed the specified value?

14 kPa (2 psi)

Go to Step 5

Go to Step 7

5 | Inspect the exhaust system for the following conditions:

• | Internal damage to the exhaust component

• | Debris in the exhaust pipe

• | Muffler or resonator internal failure

• | Two-layer exhaust pipe separation

Did you find and correct the condition?

--

Go to Step 7

Go to Step 6

6 | Replace the catalytic converter. Refer to Catalytic Converter Replacement. Is replacement complete? | -- | Go to Step 7 | --
7 |

1. Clear any diagnostic trouble codes.
2. Road test the vehicle in order to verify the repair.

Did you correct the condition?

--

System OK

Go to Step 2