FixVault
Home
›
Buick
›
2003
›
Regal LS
›
Repair and Diagnosis
›
Engine Performance
›
System
›
Engine Control System Self-Diagnostics - 3.8L
›
Diagnostic Tests
›
DTC P0420: Catalyst System Low Efficiency
›
Conditions For Setting DTC
Conditions For Setting DTC
DTC sets when PCM determines catalysts oxygen storage capacity is less than an acceptable threshold.