P0091

Fuel Pressure Regulator 1 Control 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 30 minutes – 4 hours

Typical cost SAR 100 to 5,000

What it means

The engine computer has detected lower than expected voltage in the fuel pressure regulator control circuit, most often from a control wire shorted to ground or an open regulator coil or feed. When the computer loses control of the regulator, the engine may enter limp mode with reduced power, and it may be hard to start or stall.

Symptoms4

Check engine light on.
Reduced power or limp mode.
Hard starting, or a no-start on some vehicles.
Stalling or rough running.

Possible causes5

Control wire shorted to ground (vehicle body) through rubbed insulation.
Open regulator coil or lost power feed.
Blown supply fuse.
Corroded connector or moisture inside it.
ECU fault (rare).

How to diagnose5

Check the fuse feeding the regulator; if it has blown, find the short before replacing it.
Unplug the regulator and measure its coil resistance; an open reading means a failed coil.
With the ECU and regulator unplugged, check the control wire for continuity to ground.
Confirm supply voltage reaches the connector with the ignition on.
Wiggle the wiring while measuring to catch an intermittent fault.

How to fix5

Clean and reseat the connector and repair any corroded pin.
Repair broken or chafed wiring and remove any short to ground.
Replace a blown fuse after removing the cause of the short.
Replace the pressure regulator if its coil resistance is out of specification, or the high-pressure pump if the regulator is part of it.
Clear the codes, road test and confirm pressure returns to its desired value and 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 when a connector or wire is to blame, rises for a new regulator, and reaches the upper end on engines where the regulator is part of the high-pressure pump.

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

Does this code mean the high-pressure pump is bad?

Not necessarily. This is an electrical circuit code, and a wire or connector is often the cause. On some engines, though, the regulator is mounted on the high-pressure pump and sold with it.

What is the difference between P0091 and P0092?

P0091 means low voltage, usually from a short to ground or an open coil or feed, while P0092 means high voltage, usually from a short to a voltage source or an internally shorted coil.

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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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