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Toyota Corolla Repair Manual: Catalyst system efficiency below threshold

Toyota Corolla Repair Manual / Diagnostics / Sfi system / 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. Airfuel 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 failsafe and turns the ot ...

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