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Home/DTC Codes/Lincoln/MKX/2014-2014 3.7L V6/P3604
P3604

Start-Stop Brake Vacuum Pump Performance

2014-2014 Lincoln MKX 3.7L V6

High SeverityPowertrainGeneric (SAE)

The 2014 Lincoln MKX is equipped with a 3.7L V6 engine. Below you'll find detailed p3604 diagnostic code information including labor time estimates, cost ranges, and technician notes specific to this engine configuration.

Description

The electric brake vacuum pump that maintains brake boost during engine-off periods in start-stop systems is not providing adequate vacuum.

Symptoms

  • Start-stop disabled
  • Firm brake pedal during engine stop
  • Brake assist warning
  • Start-stop inhibited due to brake system
  • Hard pedal after one or two stops

Common Causes

  • Electric vacuum pump motor weak
  • Check valve in vacuum line leaking
  • Vacuum line crack or disconnect
  • Pump control module fault
  • Brake booster diaphragm leak

Diagnostic Steps

  1. Monitor brake vacuum level during engine-off events
  2. Test electric vacuum pump operation
  3. Check vacuum lines and check valves
  4. Measure vacuum decay rate with engine off
  5. Test brake booster for leaks

Repair Notes

Replace electric vacuum pump or check valve. Repair vacuum line leaks. Ensure brake boost is adequate during engine-off periods.

Related Codes

P3600Auto Start-Stop System MalfunctionP3601Auto Start-Stop Restart Failure

Other Powertrain Codes

P3604 on Other Vehicles

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Common Questions

What does code P3604 mean on a 2014-2014 Lincoln MKX?

P3604 stands for "Start-Stop Brake Vacuum Pump Performance". The electric brake vacuum pump that maintains brake boost during engine-off periods in start-stop systems is not providing adequate vacuum.

What are the symptoms of P3604 on a Lincoln MKX?

Common symptoms of P3604 include: Start-stop disabled, Firm brake pedal during engine stop, Brake assist warning, Start-stop inhibited due to brake system, Hard pedal after one or two stops.

What causes P3604 on a 2014-2014 Lincoln MKX?

Common causes of P3604 include: Electric vacuum pump motor weak, Check valve in vacuum line leaking, Vacuum line crack or disconnect, Pump control module fault, Brake booster diaphragm leak.

Last updated: March 2026

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