P1407 Buick EGR Air Intrusion In Exhaust Supply To EGR Valve

P1408 Buick EGR Flow Out Of Self Test Range

Possible causes
For vacuum activated systems, see the possible causes for DTC P0401 Buick. For electric motor systems, see the possible causes for DTC P0400 Buick.
Symptoms
– Engine Light ON (or Service Engine Soon Warning Light)
P1408 Buick Description

This test is performed during the KOER on-demand self-test only. The EGR system is commanded on at a fixed engine speed. The test fails and the DTC is output when the measured EGR flow falls above or below the required calibration .

Buick Vehicle:Buick Regal – ?Buick Riviera – ?Buick LaCrosse – ?David Dunbar Buick – Buick Century – Buick LaCrosse – Buick LeSabre – Buick Lucerne – Buick Park Avenue – Buick Regal – Buick Verano – Buick Enclave – Buick Encore – Buick Rainier – Buick Rendezvous – Buick Terraza – Buick Riviera