Question

What does P0420, P0440, P0441, and P0446 mean as far as engine light codes are concerned? I have a 2002 Toyota Camry 6 Cyl

Answer 1

P0420 Catalyst sytem efficiency below threshold (bank 1)

P0440 Evaporative emission control system malfunction

P0441 Evaporative emmission control system inncorrect purge flow

P0446 Evaporative emission control system vent control circuit

P0441 is the main code condition which can trigger the rest of the code conditon, At the airfilter housing are EVAP hoses if the purge line hose (EVAP hose part) ever gets   disconnected . You code a P0440 and without a purge vacuum there is no EVAP. vent action and being after the MAF (mass airflow) this can create unmetered air or false air that can lean the system and lean the catalytic effiecieny. Correct for P0441 only.