Toyota Corolla (E120) 2002–2008 Repair Manual / Diagnostics / Sfi system / Catalyst system efficiency below
threshold
Toyota Corolla (E120): Catalyst system efficiency below threshold
Dtc p0420 catalyst system efficiency below threshold (bank 1)
Other materials:
On–vehicle inspection
1. Inspection throttle body idle speed control valve assy
Notice:
it is impossible to check the resister value and the operation
of isc valve by itself, because the isc valve
has an ic circuit inside it, which transforms the duty
signal from the ecm to the derive signal.
After check ...
Inspection procedure
1 Check operation(overdrive)
Drive the vehicle after the engine warms up.
check that overdrive on e off occurs by an operation of the o/d
switch on–off.
2 Inspect terminal voltage(od)
Remove the cruise control ecu assy with the connector
still connected.
tur ...
Inspection procedure
1 Inspect cruise control actuator assy
Turn the ignition switch to off.
disconnect the cruise control actuator assy connector.
measure the resistance between terminals 1 (mo) and 2
(mc) of cruise control actuator assy.
Hint:
if control plate position is fully opened or ...