For 1990-2009 cars

Schematic Reference: Engine Controls Schematics

#### Restricted Exhaust System Check

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | Go to Step 2 | Go to Powertrain On Board Diagnostic (OBD) System Check
2 |

1. Remove the AIR check valve on the side of the engine that is suspected of being restricted.
2. Install the Exhaust Back Pressure tester J 35314-A in place of the AIR check valve.
3. Engine idling 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

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

If a driveability symptom exists, refer to Symptoms

4 |

1. Turn the Engine OFF.
2. Re-install the AIR check valve.
3. Remove the rear HO2S sensor on the side of the engine that is suspected of being restricted.
4. Install the Exhaust Back Pressure tester J 35314-A in place of the HO2S sensor.
5. Start and 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

5 | Repair the restriction in the exhaust system after the Catalytic Converter. Check exhaust system for the following:

• | Collapsed pipe

• | Heat distress

• | Internal muffler failure

Is the action completed?

--

System OK

--

6 | Replace Catalytic Converter. Refer to Exhaust System Is the action completed? | -- | System OK | --