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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:

Inspection procedure
1 Input signal check See input signal check on page 05745. check the indicator light operation when each of the set/ coast, resume/accel and cancel is turned on. Ok: set/coast, resume/accel switch: the signals shown in the table on the left should be output when each switch is o ...

Inspection procedure
1 Check operation(starter) Check that the starter operates normally and that the engine starts. 2 Input signal check See input signal check on page 05745.  check the indicator light when shifting into except d position. Ok: the indicator light goes off when shifting in ...

Circuit description
The shift solenoid valve sl is turned on and off by signals from the ecm in order to control the hydraulic pressure operation, the lockup relay valve, which then the controls operation of the lockup clutch. Fail safe function: if the ecm detects a malfunction, it turns the shift solen ...

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