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DTC - Diagnostic Trouble Codes information

P0420

Powertrain Codes

P0420 - TOYOTA - Catalyst System Efficiency Below Threshold (Bank 1)

Symptoms

- Engine Light ON (or Service Engine Soon Warning Light)

Possible Causes

- Three way catalyst converter Bank 2 - Exhaust tube - Intake air leaks - Fuel injectors may be faulty - Fuel injector leaks - Spark plugs may be faulty - Improper ignition timing - Engine Control Module (<

When Detected

- Three way catalytic converter Bank 1 does not operate properly. - Three way catalyst converter Bank 1 does not have enough oxygen storage capacity.

Description

The ECM or PCM monitors the switching frequency ratio of heated oxygen sensors 1 and 2. A three way catalyst converter(Manifold) with high oxygen storage capacity will indicate a low switching frequency of heated oxygen sensor 2. As oxygen storage capacity decreases, the heated oxygen sensor 2 switching frequency will increase. When the frequency ratio of heated oxygen sensors 1 and 2 approaches a specified limit value, the three way catalyst (Manifold) malfunction is diagnosed.