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:
Circuit description
A thermistor is built in the engine coolant temperature sensor and changes
the resistance value according
to the engine coolant temperature.
The structure of the sensor and connection to the ecm is the same as those of
the intake air temperature
sensor.
Hint:
if the ecm detects the dtc ...
If your vehicle has to be stopped in an emergency
Only in an emergency, such as if it becomes impossible to stop the vehicle
in the normal way, stop the vehicle using the following procedure:
1 Steadily step on the brake pedal with both feet and firmly depress it.
Do not pump the brake pedal repeatedly as this will increase the effort required ...
Check short circuit
If the wire harness is ground shorted as shown in fig. 5,
Locate the section by conducting a resistance check with
the body ground in step (b).
Check the resistance with the body ground.
Disconnect connectors a and c and measure the
resistance between terminals 1 and 2 ...