Possible causes

For vacuum activated systems, see the possible causes for DTC P0401. For electric motor systems, see the possible causes for DTC P0400.

Symptoms

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

P1408 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 .

P1408 Information for specific makes

P1408 BUICK
P1408 CADILLAC
P1408 CHEVROLET
P1408 FORD
P1408 GMC