For 1990-2009 cars

#### Excessive Exhaust Emissions or Odors Symptom

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
Definition: Vehicle fails an emission test. Vehicle has excessive rotten egg smell. (Excessive odors do not necessarily indicate excessive emissions.)
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. Perform a bulletin search.
2. If a bulletin that addresses the symptom is found, correct the condition as instructed in the bulletin.

Was a bulletin found that addresses the symptom?

--

Go to Step 13

Go to Step 3

3 | Perform the careful visual/physical checks as described at the start of Symptoms section. Was the visual/physical check performed? | -- | Go to Step 4 | Go to Important Preliminary Checks
4 |

1. Check for vacuum leaks. (vacuum lines, intake manifold, throttle body etc.).
2. If a problem is found, repair as necessary.

Were any vacuum leaks located?

--

Go to Step 13

Go to Step 5

5 | Check the MAP sensor for proper operation. Refer to Manifold Absolute Pressure Sensor Output Diagnosis . Was a problem found? | -- | Go to Step 12 | Go to Step 6
6 |

1. Check the fuel pressure. Perform procedure in Fuel System Diagnosis .
2. If a problem is found, repair as necessary.

Was a problem found?

--

Go to Step 12

Go to Step 7

7 |

1. Check the injector connections.
2. If any of the injectors are connected to an incorrect cylinder, correct as necessary.

Was a problem found?

--

Go to Step 12

Go to Step 8

8 |

1. Perform the Fuel Injector Solenoid Coil Test and Fuel Injector Balance Test .
2. If a problem is found, repair as necessary.

Was a problem found?

--

Go to Step 12

Go to Step 9

9 |

1. Check cooling system for proper operation.
2. Refer to Engine Cooling for cooling system diagnosis.
3. If a problem is found, repair as necessary.

Was a problem found?

--

Go to Step 12

Go to Step 10

10 |

1. Check the EVAP canister for fuel loading.
2. If a problem is found, repair as necessary.

Was a problem found?

--

Go to Step 12

Go to Step 11

11 |

1. Remove any excessive carbon buildup with a top engine cleaner, refer to the instructions on of the top engine cleaner can.

Is the action complete?

--

Go to Step 12

--

12 | Reevaluate the vehicles emissions. Are the vehicles emission levels ok? | -- | Go to Step 19 | Go to Step 13
13 | Does the exhaust emission test indicate excessive CO and HC levels or is the Long Term Fuel Trim significantly in the negative range (Rich condition)? | -- | Go to Step 14 | Go to Step 15
14 |

1. Check the items that can cause the engine to run rich. Refer to DTC P0172 Fuel Trim System Rich for diagnosis. Make any necessary repairs.

Were any repairs necessary?

--

Go to Step 12

Go to Step 16

15 |

1. Check the items that can cause the engine to run lean. Refer to DTC P0171 Fuel Trim System Lean for diagnosis. Make any necessary repairs.

Were any repairs necessary?

--

Go to Step 12

Go to Step 16

16 |

1. Check the catalytic converter for lead contamination.
2. If a problem is found, repair as necessary.

Was a problem found?

--

Go to Step 12

Go to Step 17

17 |

1. Check for an engine mechanical problem. Perform a cylinder compression check Refer to Engine Mechanical .
2. If a problem is found, repair as necessary.

Was a problem found?

--

Go to Step 12

Go to Step 19

18 |

1. Check for a fouled Rear Heated Oxygen Sensor and replace as necessary. Refer to DTC P0138 HO2S Circuit High Voltage Sensor 2 Diagnostic Aids .
2. Replace the Catalytic Converter.

Is the action complete?

--

Go to Step 20

--

19 |

1. Review all diagnostic procedures within this table.
2. If all procedures have been completed and no malfunctions have been found, review/inspect the following items:

• | Visual/physical inspection.

• | Scan tool data.

• | All electrical connections within a suspected circuit and/or system.

3. If a problem is found, repair as necessary.

Was a problem found?

--

Go to Step 20

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20 | Operate vehicle within the conditions under which the original symptom was noted. Does the system now operate properly? | -- | System OK | Go to Step 2