P3657high severityPowertrain
GDI Fuel System Priming Pump Performance
on 2011 Lincoln MKX 3.7L V6 · AWD
What this code means
The low-pressure electric fuel pump that primes the GDI high-pressure fuel system is not delivering adequate fuel volume or pressure to the HP pump inlet.
Symptoms
- Extended cranking time
- Hard start after sitting
- Fuel rail slow to build pressure
- Engine stalling after start
- HP pump cavitation noise
Common causes
- Weak fuel pump motor
- Clogged fuel filter
- Fuel pump check valve leak
- Fuel tank pickup sock restricted
- Fuel pump relay intermittent
Diagnostic steps
- Measure fuel pressure at HP pump inlet
- Test electric fuel pump current draw
- Check fuel filter restriction
- Test fuel pump check valve hold pressure
- Inspect fuel pump relay and wiring
Repair notes
Replace low-pressure fuel pump or fuel filter. GDI systems are sensitive to feed pressure - even slight deficiency causes HP pump issues.
🔌 Don't have a code reader?
Any of these will read and clear this code — pick by how deep you want to go.
Budget handheld~$40
ANCEL AD410 →
No-phone-needed handheld — reads, clears, live data, freeze frame.
✓ ANCEL official store
Serious DIY~$100
BlueDriver Pro →
Enhanced codes (ABS, airbag, TPMS) plus repair reports.
SHOP FAVORITEShop-grade tablet~$300
Autel MaxiCOM MK808S →
Bidirectional tests, service resets, all systems.
✓ Autel official store
Pro diagnostics$1,500+
Autel MaxiSys MS906 Pro →
Full-system pro platform — topology mapping, ECU coding, the works.
✓ Autel official store
As an Amazon Associate and Autel/ANCEL partner, OLP earns from qualifying purchases — how we link. This never changes the specs we publish.
Other Powertrain codes on this vehicle
P0001
Fuel Volume Regulator Control Circuit/Open
P0001
Fuel Volume Regulator Control Circuit/Open
P0002
Fuel Volume Regulator Control Circuit Range/Performance
P0002
Fuel Volume Regulator Control Circuit Range/Performance
P0003
Fuel Volume Regulator Control Circuit Low
P0003
Fuel Volume Regulator Control Circuit Low
P0004
Fuel Volume Regulator Control Circuit High
P0004
Fuel Volume Regulator Control Circuit High
P0010
Intake Camshaft Position Actuator Circuit/Open Bank 1
P0010
Intake Camshaft Position Actuator Circuit/Open Bank 1