my 2005/2006 Ford focus hatchback car developed a stalling, jerking and sudden stop problem for 3months now. I have changed the spark plugs, ignition coil, fuel relay, used 9fuel pumps, changed slow jet, changed air collector, used 2 fuel pump casings, inner & outer fuel filters and changed the brain box all to no avail. I have also washed my fuel tank from clogs. Diagnosis displayed error code PO230. Please, what could be the possible element that reduces voltage to the pump thereby damaging it 20 minutes after installation/change. Thanks

  • So you multi metered the fuel pump connection, what volts are you getting? Are you sure its been the fuel pump each time? Does it drive normal leading up to those 20 minutes? if your worried about the wiring run a new positive directly from the battery and use the old wiring harness to trigger a relay
    – DatsunZ1
    Dec 6, 2018 at 22:42
  • I am yet to Meter test the fuel pump connections. Please, What readings do I expect? It drives normal before the 20minutes Grace period. I have also powered the pump directly from the battery all to no avail. Could it possibly be the alternator? Dec 7, 2018 at 0:00

1 Answer 1


You need to check the fuel pump relay, as well as the inertia "crash" switch in the rear of the vehicle. Those are the likely things that can cause a P0230 on a Ford focus.

The only other possibility is the crank shaft sensor, which pulses the ECM and causes the fuel pump to be kept "live" and running. I doubt the problem is here, as the vechicle would not run well at all with a failed CPS crankshaft sensor. While it's possible this sensor is overheating and causing the problem, I would look at the fuel pump relay and inertia switch first.

  • I have changed the fuel pump relay and the problem still persists but I didn't check for any possible drop in voltage. However the inertia switch seems to be working cause I tried starting the car when it was turned off and the car refused coming up. Alternatively, I would check the current entering and exiting the device. Please do you think a drop in the voltage from the alternator could be the cause? Does the alternator have a direct link to the fuel pump? Dec 9, 2018 at 17:35
  • If the inertia switch is bad, you won't be able to start the car. Bypass the switch and see if the problem still persists. If you have reasonable battery voltage (12.5 volts or better) the alternator is certainly not the issue.
    – SteveRacer
    Dec 24, 2018 at 8:02
  • Hi. I took voltage readings for the battery, relay, inertia switch, alternator and fuel pump. When engine is idle, battery-12.48v & cranking-13.5v. When engine is idle, alternator-12.49v & cranking-13.77v. When engine is cranking, Inertia feed cable before switch-12.92v & after switch-12.84v. When engine is cranking, fuel pump-12.6v & during the stalling, jerking & sudden stop situation fuel pump-11.6v. The problem is intermittent. it occurs at odd times one cannot predict especially when the A/C is on. How do I bypass the inertia switch? Can I bypass for up to 48hours without Counter effects? Dec 28, 2018 at 11:27

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