Toyota Corolla Repair Manual: Catalyst system efficiency below threshold
Dtc p0420 catalyst system efficiency below threshold (bank 1)
Inspection procedure
Hint:
read freeze frame data using the hand-held tester or the obd ii scan tool.
Freeze frame data records the
engine conditions when a malfunction is detected. When troubleshooting, it is
usefu ...
Circuit description
The ecm compares the two waveforms of the heated oxygen sensors located
before and after the catalyst
to determine whether or not the catalyst performance has deteriorated.
Air–fuel ratio feedba ...
Other materials:
Replacing a flat tire
1 Chock the tires.
2 For vehicles with steel wheels, remove the wheel ornament using the wrench.
To protect the wheel ornament, place a rag between the wrench and the wheel ornament,
as shown in the illustration.
3 Slightly loosen the wheel nuts (one turn).
4 Turn the tire jack portion ...
Inspection procedure
1 Check d squib circuit(airbag sensor assy center – horn button
assy)
Disconnect the negative (–) terminal cable from the battery,
and wait at least for 90 seconds.
disconnect the connectors between the airbag sensor
assy center and the horn button assy.
for the orange c ...
Circuit description
Monitor description
The ecm commands gearshift by turning the shift solenoid valves ”on/off”.
When there is an open or short
circuit in any shift solenoid valve circuit, the ecm detects the problem and the
mil comes on. Illuminating
the mil, the ecm performs the fail–safe and turns the ot ...