DEFINITION: Vehicle has excessive rotten egg smell. Excessive odors do not necessarily indicate excessive emissions.

Was the Powertrain On-Board Diagnostic (OBD) System Check performed?

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Go to Step 2

Go to Powertrain (OBD) System Check

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?

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Go to Step 18

Go to Step 3

Was a thorough visual and physical check performed?

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Go to Step 4

Go to Visual/Physical check in Symptoms

1. Check the following locations for vacuum leaks:

•	The vacuum lines

•	The EGR system

•	The intake manifold

•	The throttle body

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

Were any vacuum leaks located?

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Go to Step 18

Go to Step 5

1. Check the fuel cap for proper installation.
2. Secure the fuel cap if necessary.

Was the fuel cap installed properly?

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Go to Step 6

Go to Step 18

1. Check the fuel pressure. Refer to Fuel System Pressure Test (VIN K) or to Fuel System Pressure Test (VIN 1) .
2. If a problem is found, repair as necessary.

Was a problem found?

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Go to Step 18

Go to Step 7

1. Check for faulty, plugged, or incorrectly installed crankcase ventilation valve. Also check the crankcase ventilation system for restrictions. Refer to Crankcase Ventilation System Inspection .
2. If a problem is found, repair as necessary.

Was a problem found?

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Go to Step 18

Go to Step 8

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

Was a problem found?

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Go to Step 18

Go to Step 9

1. Perform the Injector Flow/Voltage Drop Check. Refer to Fuel Injector Balance Test with Special Tool , Fuel Injector Balance Test with Tech 2 , Fuel Injector Solenoid Coil Test - Engine Coolant Temperature Between 10-35 Degrees C (50-95 Degrees F) and Fuel Injector Solenoid Coil Test - Engine Coolant Temperature Outside 10-35 Degrees C (50-95 Degrees F) .
2. If a problem is found, repair as necessary.

Was a problem found?

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Go to Step 18

Go to Step 10

1. Refer to Diagnostic System Check in Engine Cooling.
2. If a problem is found, repair as necessary.

Was a problem found?

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Go to Step 18

Go to Step 11

1. Check the EVAP canister for fuel loading. Refer to Evaporative Emission Control System Diagnosis .
2. If a problem is found, repair as necessary.

Was a problem found?

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Go to Step 18

Go to Step 12

Remove an excessive carbon buildup with Top Engine Cleaner. Refer to the instructions on the Top Engine Cleaner can.

Is the exhaust odor still present?

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Go to Step 13

Go to Step 18

Check the items that can cause the engine to run rich. Make any necessary repairs. Refer to Diagnostic Aids in DTC P0172 Fuel Trim System Rich .

Is the exhaust odor still present?

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Go to Step 14

Go to Step 18

Check items that can cause the engine to run lean. Make any necessary repairs. Refer to Diagnostic Aids in DTC P0171 Fuel Trim System Lean .

Is the exhaust odor still present?

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Go to Step 15

Go to Step 18

1. Check the EGR system.
2. If a problem is found, repair as necessary.

Was a problem found?

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Go to Step 18

Go to Step 16

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

Was a problem found?

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Go to Step 18

Go to Step 17

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

•	The scan tool data

•	The Freeze Frame and Failure Records data.

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

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

Was a problem found?

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Go to Step 18

Go to Powertrain (OBD) System Check

Operate the vehicle within the conditions present when the original symptom was noted.

Is symptom still present?

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Go to Step 3

System OK