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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:

Check open circuit
For the open circuit in the wire harness in fig. 1, Perform a resistance check in step (b) or a voltage check in step (c) to locate the section. Check the resistance.  Disconnect connectors a and c and measure the resistance between them. Resistance: 1 Ω or les ...

Windshield wiper switch assy
Replacement 1. Remove steering column cover lwr Remove 3 screws and steering column cover lwr. 2. Remove windshield wiper switch assy Disconnect the connecter of the windshield wiper switch.  release the claw and pull out the windshield wiper switch assy as shown in the ...

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 useful for determining whether the vehicle was running or stopped, the engine was warmed up or not, the ...

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