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P1243

Second Fuel Pump Faulty or Ground Fault.

  • Ford
  • Powertrain
  • Manufacturer code
  • Medium severity

How this code is built

P
SystemPowertrain
1
Defined byThe manufacturer
2
AreaFuel and air metering (injector circuit)
43
FaultThe specific fault in that area

What it means

P1243 on a Ford means the powertrain control module has detected a fault in the second fuel pump circuit, or a ground fault associated with it. The module monitors the control and feedback of the second pump, and sets the code when the expected electrical state does not match what it sees. Which vehicles have a second pump, and how it is controlled, depends on the model and engine.

Symptoms

  • Engine cranks but is slow to start or does not start
  • Hesitation, misfire or loss of power under load
  • Engine stalls or cuts out, especially with low fuel or high demand
  • Whining or no audible noise from the fuel tank area
  • Malfunction indicator lamp on
  • Poor fuel economy or rough running

Possible causes

  • Poor or corroded ground connection for the second fuel pump or its relay circuitlikely
  • Wiring damage, chafing or open or short circuit in the second pump feed or control circuitlikely
  • Corroded or loose connector at the pump, tank harness or relay/modulelikely
  • Failing second fuel pump drawing excessive current or not runningpossible
  • Faulty fuel pump relay or fuel pump driver/control modulepossible
  • Blown fuse in the second pump supplypossible
  • Fault inside the powertrain control modulerare

How to diagnose

  1. Read all stored codes and freeze frame data, noting fuel level, engine load and speed when the code set, and check for other fuel or driver circuit codes
  2. Check the fuel pump fuses and relay for the second pump using the wiring diagram for the specific model and engine
  3. Inspect the wiring, connectors and earth points between the PCM, relay, tank and pump for corrosion, chafing, water ingress or heat damage
  4. Check the earth connection for voltage drop with the circuit loaded, and clean or repair as needed
  5. Listen for the second pump running at key on and check that supply voltage and ground are present at the pump connector
  6. Measure pump current draw and compare it with the manufacturer specification for that model
  7. Check fuel pressure and volume against specification to confirm whether the pump is delivering
  8. Swap in a known good relay, or test the driver circuit, before condemning the PCM

How to fix

  • Clean, tighten or repair the earth connection and renew corroded terminals
  • Repair or replace damaged wiring and connectors in the second pump circuit
  • Replace a blown fuse only after finding and fixing the cause of the overload
  • Replace the second fuel pump if it is open circuit, seized or drawing excess current
  • Replace a faulty fuel pump relay or driver module
  • Replace or repair the PCM only if testing proves the driver circuit fault is internal

Can I keep driving?

Medium severity

The car may run, but a failing second pump can cause hesitation, loss of power or a stall, which is a safety risk in traffic. Get it checked soon and avoid long journeys or low fuel levels until it is fixed.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.

This code for other makes

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