P2000 Buick Oxides of Nitrogen Trap Efficiency Below Threshold Bank 1

P2001 Buick Oxides of Nitrogen Trap Efficiency Below Threshold Bank 2

Possible causes
– Sensor or solenoid faulty
– Connector terminal contact is damaged or corroded
– Wire harness – Check harness for correct voltage, open, short to ground or short to voltage
– Update control unit software – Check for the latest control unit update
– Powertrain or Engine Control Module faulty
– Catalytic converter damage
– Catalytic converter improper operation

Symptoms
– Engine Light ON (or Service Engine Soon Warning Light)
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