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Home >> Chevrolet >> 2003 >> Impala LS >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System Self-Diagnostics - 3.8L >> Diagnostic Tests >> DTC P0420: Catalyst System Low Efficiency >> Diagnostic Procedures
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Diagnostic Procedures

Fig 1: DTC P0420: Catalyst System Low Efficiency (Steps 1-8)
G00250400Courtesy of GENERAL MOTORS CORP.
Fig 2: DTC P0420: Catalyst System Low Efficiency (Steps 9-11)
G00250401Courtesy of GENERAL MOTORS CORP.
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