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Fault Code P0420

Posted: Fri Jun 16, 2017 6:57 am
by VWJettaGuy
This year the check engine light comes one. ODBC scanner reports 'P0420 Catalyst System Efficiency Below Threshold Bank 1'. Cleared code several times and returns a few weeks later. Used Chevron Techron Complete Fuel System Cleaner and no check engine for at least 3 months. Check engine light reappeared this week and same fault code. Next step is clean MAF and throttle body before considering a costly catalytic converter replacement.

04 VW Jetta GLS
2.0L L4 SOHC 20V
WAGON 4-DR
Engine Code BEV