Possible causes
– Three way catalyst converter Bank 1
– Exhaust tube
– Intake air leaks
– Fuel injectors may be faulty
– Fuel injector leaks
– Spark plugs may be faulty
– Improper ignition timing
– Engine Control Module (ECM)
– Exhaust tube
– Intake air leaks
– Fuel injectors may be faulty
– Fuel injector leaks
– Spark plugs may be faulty
– Improper ignition timing
– Engine Control Module (ECM)
Tech description
As the code description implies the P0421 code means that the vehicle’s control module has detected that the three-way catalytic converter is not working properly (is not as efficient as the factory is expecting). Replacing the oxygen (O2) sensors may sometimes fix the code, but in most cases the catalytic convert needs to be replaced to fix the problem. If the P0421 code is combined with other codes, try fixing the other codes first.
When is the obd code mean?
– Three way catalytic converter Bank 1 does not operate properly.
– Three way catalyst converter Bank 1 does not have enough oxygen storage capacity.
– Three way catalyst converter Bank 1 does not have enough oxygen storage capacity.
Symptoms
– Engine Light ON (or Service Engine Soon Warning Light)
P0421 HYUNDAI OBD Code Description
The catalyst