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Hummer
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2009
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H3 Base, Standard
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Repair and Diagnosis
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Engine Performance
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System
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Engine Controls And Fuel - 3.7L - DTC P0324 To DTC P0446
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DTC P0420
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Repair Procedures
Repair Procedures
NOTE:
A new converter with less than 100 miles on it may set DTC P0420 due to out-gassing of the internal matting. Operating the vehicle at highway speeds for approximately 1 hour may correct the condition.
Catalytic Converter Replacement (LLR)
Heated Oxygen Sensor Replacement - Sensor 2
Exhaust Leakage
Restricted Exhaust