P2543 critical

Fuel Cutoff Switch Circuit

The P2543 code means the vehicle's onboard diagnostic system has detected: Fuel Cutoff Switch Circuit. This is a critical severity code.

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Keep driving?: No -- stop driving
DIY difficulty: easy
Estimated cost: $0 - $200 (parts and labor)

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Common Symptoms

Engine will not start after minor impact
Fuel pump not running
No fuel delivery to engine
Check engine light on

Probable Causes (Ranked by Likelihood)

Inertia fuel cutoff switch tripped from impact Very High
Faulty fuel cutoff switch High
Wiring damage to cutoff switch circuit Moderate
ECM not receiving cutoff switch reset signal Low

Step-by-Step Diagnostic Procedure

Locate and reset the inertia fuel cutoff switch
Test fuel cutoff switch circuit for continuity after reset
Check wiring between cutoff switch and fuel pump relay
Verify fuel pump operates after switch is reset

Frequently Asked Questions

Where is the inertia fuel cutoff switch?

On Ford vehicles it is typically located in the trunk, behind a kick panel in the rear cargo area, or under the dashboard. Check your owner manual for the exact location.

How do I reset the fuel cutoff switch?

Press the reset button on top of the switch. It is a simple push-button that pops up when tripped and resets when pressed down. Verify no fuel leaks before restarting.

Can hitting a pothole trip the fuel cutoff switch?

Yes. A hard bump, pothole, or even a curb strike can generate enough force to trip the inertia switch, cutting off fuel to the engine as a safety measure.