P1408 - Exhaust Gas RECIRCULATION (EGR) Flow Out Of Self-Test Range

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P1408 - EXHAUST GAS RECIRCULATION (EGR) FLOW OUT OF SELF-TEST RANGE

Description: This test is carried out during the key ON, engine running (KOER) on demand self-test only. The EGR system is commanded on at a fixed engine speed. This DTC sets when the measured EGR flow falls above or below the required calibration.
Possible Causes: For electric EGR (EEGR) system, EEGR valve stuck open or closed EEGR connector not seated correctly EEGR stepper motor VPWR circuit open EGRMC circuit open EGRMC circuit short to voltage EGRMC circuit short to ground Vacuum signal to manifold absolute pressure (MAP) sensor restricted or leaking Mass airflow (MAF) sensor signal erroneous Carbon build up in the EEGR valve seat area For vacuum activated systems, Vacuum supply EGR valve stuck closed EGR valve leaks vacuum EGR flow path restricted EVR circuit short to voltage VREF open to the differential pressure feedback EGR sensor Differential pressure feedback EGR sensor downstream hose is off or plugged EVR circuit open VPWR open to EGR vacuum regulator solenoid Differential pressure feedback EGR sensor hoses are both off Differential pressure feedback EGR sensor hoses are reversed Damaged EGR orifice tube Damaged EGR vacuum regulator solenoid
Diagnostic Aids: For EEGR, use the output state control function of the scan tool and monitor the manifold absolute pressure (MAP) PID and the EEGR PID (EGRMDSD) while commanding the EEGR on. If EGR is introduced into the engine at idle, the RPM drops or stalls out. For vacuum systems, look for contamination, restrictions, leaks, and intermittent concerns.
Application	Key On Engine Off	Key On Engine Running	Continuous Memory
E-Series 4.6L, Mustang 5.8L	GO to PINPOINT TEST HH: EXHAUST GAS RECIRCULATION SYSTEM MODULE (ESM) .
All others	GO to PINPOINT TEST KD: ELECTRIC EXHAUST GAS RECIRCULATION (EEGR) SYSTEM .