Test Description

NOTE: Test numbers refer to numbers on diagnostic flow chart (1 Of 2).

Fig 1: Code P1406 Schematic (3.8L) EGR Valve Pintle Position

Fig 2: Code P1406 Diagnostic Flow Chart - 1 Of 2 (3.8L) EGR Valve Pintle Position

Checks for an EGR valve sticking partially open or an incorrect pintle position sensor feedback signal.
Ensures PCM is capable of controlling EGR pintle position and is reading pintle position feedback signal properly.
Checks EGR valve driver in circuit and PCM.

NOTE: Test numbers refer to numbers on diagnostic chart (2 Of 2).

Fig 3: Code P1406 Diagnostic Flow Chart - 2 Of 2 (3.8L) EGR Valve Pintle Position

Checks will diagnose an incorrect EGR pintle position sensor input signal. This test verifies a 5-volt reference at EGR valve.
Ensures position signal circuit is not shorted to ground.
Checks position signal circuit for an open.