P0421 VOLKSWAGEN -

Question

Pep Boys said P0421 code. Engine seems to run fine, but check-engine light on. P0421 and P0441 were the only two codes their device found.

Answer 1

P0421 Warm up catalytst effieciency below threshold bank 1

P0441 Evaporative emission system incorrect purge flow

For P0421 the 02 sensor wwhich is behind the catalytic needs to be inspected for proper operation , a failed 02 will set code P0421 as for P0441 a failed fuel cap that does not properly sealed can set a incorrect purge flow,

Answer 2

Thanks.  This is what I needed.