P0231 code

Anyone know what causes this code. Fuel pump circuit low voltage.

BTW- the code list sticky is missing all the 200 codes!

Nobody????

What year and engine size?

99' with 3.8L

The info I have doesn't include the 99 year or lower, sorry
This is for a 2000 3.8L, should be same or similar... at least is a start, hope it helps

P0231 - Fuel Pump Secondary Circuit Low

NOTE: For natural gas applications, the following description applies to the fuel shutoff valve monitor (FSVM) and the fuel shutoff valve power (FSV PWR) circuits. The PCM monitors the fuel pump monitor (FPM) circuit. The test fails if the PCM commands the fuel pump ON and B+ voltage is not detected on the FPM circuit.

Possible causes:
Open B+ circuit to the fuel pump relay
Open FP PWR circuit between the fuel pump relay and its connection to the FPM circuit
Damaged fuel pump relay
Damaged PCM (engine will start)
For 4.6L Mustang, open FP PWR circuit from low speed fuel pump relay, through resistor to FPM splice (engine will start)
For 5.4L SC Lightning, damaged IFS switch, IFS switch relay, or concern with related circuits.

Diagnostic Aides:
During KOEO self-test, the PCM will command the fuel pump ON so this test can be performed.


KC20 DTC P0231: DOES ENGINE START?
Note: If Key On, Engine Off (KOEO) DTC P0230 is also present and has not been checked, GO to KC1 to check primary fuel shutoff valve circuit first.

Does the engine start?
Yes DISCONNECT PCM. GO to KC13 .
No GO to KC21 .

KC21 CHECK B+ VOLTAGE TO FUEL SHUTOFF VALVE RELAY
Disconnect fuel shutoff valve relay.
Measure B+ circuit voltage at the fuel shutoff valve relay harness connector.

Is voltage greater than 10.5 volts?
Yes GO to KC22 .
No VERIFY integrity of fuse for B+ supply to fuel shutoff valve relay. If OK, REPAIR open B+ circuit. If fuse is damaged, check B+ and FSV PWR circuit for short to ground before replacing.

KC22 CHECK FOR OPEN FSV PWR CIRCUIT BETWEEN RELAY AND FSVM SPLICE
Measure resistance between FSV PWR circuit at fuel shutoff valve relay harness connector and ground.

Is resistance less than 10.0 ohms?
Yes REPLACE fuel shutoff valve relay.
No REPAIR open in FSV PWR circuit between FSVM splice and fuel shutoff valve relay.

KC30 CONTINUOUS MEMORY DTC P0232: CHECK HARNESS
Note: If Continuous Memory Diagnostic Trouble Code (DTC) P0230 is also present, GO to KC40 .

Key on, engine off.
Access FSVM PID.
Observe the PID for an indication of a fault while completing the following (the FSVM PID will turn ON when an open or short to power is detected):
Shake, wiggle, bend the FSV PWR circuit between the fuel shutoff valve relay and the fuel solenoid shutoff valves.
Shake, wiggle, bend the fuel shutoff valves ground circuits from each fuel solenoid shutoff valve to ground.
Shake, wiggle, bend the FSVM circuit between the PCM and the splice to the FSV PWR circuit.
Lightly tap inertia fuel shutoff switch and fuel shutoff valve relay to simulate road shock.
Key off.

Is fault indicated/found?
Yes ISOLATE fault and REPAIR as necessary.
No Unable to duplicate or identify fault at this time. GO to Z1 .

KC35 CONTINUOUS MEMORY DTC P0231: CHECK FUEL SHUTOFF VALVES SECONDARY CIRCUITS BETWEEN B+ SUPPLY AND FPM CONNECTION
Disconnect inertia fuel shutoff switch.
Disconnect PCM.
Install a jumper wire between PCM harness connector pins 80 (FSV) and ground.
Connect a digital multimeter between PCM harness connector pins 40 (FPM) and ground.
Key on. The fuel shutoff valve relay will activate and voltage will be greater than 10.0 volts.
Observe voltage for an indication of a fault while completing the following (the voltage will change suddenly when a fault is detected, indicating an open):
Shake, wiggle, bend the B+ circuit to the fuel shutoff valve relay.
Lightly tap the fuel shutoff valve relay to simulate road shock.
Shake, wiggle, bend the FSV PWR circuit between the fuel shutoff valve relay and the FSVM splice.
Key off.
Inspect the fuel shutoff valve relay connector for corrosion, damaged pins.

Is a fault indicated?
Yes ISOLATE fault and REPAIR as necessary.
No Unable to duplicate or identify fault at this time. GO to Z1 .

Good luck

Thanks for the info, I will check it out.

The van runs fine. I was preforming a KOEO test and this came up. Don't know if it is a real problem or not.

If you ever have unplugged the interia switch, then ran engine to bleed off fuel pressure to change the fuel filter (as per Haynes manual if you don't have guage that can bleed off pressure) this code may have been accidently set.