P0231

Fuel Pump Secondary Circuit Low

Car Fault Codes Fuel & air

Can you still drive? With care, short trips only

Who can fix it? Needs a workshop

Typical repair time 15 minutes – 3 hours

Typical cost SAR 50 to 1,800

What it means

The engine computer has detected low voltage in the fuel pump secondary circuit, which is the power feed from the relay to the pump. This usually means voltage is not reaching the pump when it is commanded on, so fuel pressure drops or is lost.

Symptoms4

Hard starting or no start.
Stalling while driving or weakness under acceleration.
No fuel pump sound when the ignition is turned on.
Check engine light on, possibly with a low fuel pressure code.

Possible causes5

Blown fuel pump supply fuse.
Corroded or burned relay contacts that carry current to the pump.
Open wire or connector between the relay and the pump, especially near the fuel tank.
Poor pump ground.
Failed or internally shorted fuel pump.

How to diagnose6

Check the pump supply fuse; if it is blown, find the cause of the short before replacing it.
Command the pump on with a scan tool and measure the voltage at the pump connector.
Measure the voltage drop on the supply and ground wires while the pump runs.
Inspect the pump connector at the tank for corrosion or burning.
If voltage and ground are good and the pump does not run, the pump is at fault.
Measure fuel pressure and compare it with the manufacturer specification to confirm pump performance.

How to fix5

Replace the failed fuse or relay.
Clean or replace the pump connector and repair the open wire.
Repair the pump ground point.
Replace the fuel pump if it is proven faulty.
Clear the codes, then start the engine, road test and confirm the code does not return.

Repair cost

0–500

500–2,000

2,000–5,000

5,000+

In Saudi riyals; the highlighted part is the expected range for this fault.

The cost is low for a fuse, relay or connector, and reaches the upper end if the fuel pump must be replaced.

Prices are rough estimates for common cars at independent workshops and vary with the car and the source of the part.
Prices last updated: September 2026

Frequently asked questions

What is the difference between the primary and secondary circuits?

The primary is the control circuit the computer uses to switch the relay, and the secondary is the power circuit carrying voltage from the relay to the pump.

Why does the pump fuse blow?

Usually because an old pump draws too much current or a wire touches the body, so replacing the fuse alone is not enough without finding the cause.

Can I drive with this code?

Only with great care if the engine runs, because the pump may stop suddenly and stall the engine while driving.

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This guide is for information only and does not replace an inspection by a qualified technician. If the fault involves brakes, steering, engine temperature, electrics or refrigerant, do not attempt the repair yourself.

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