P0091 fault code: what it means

P0091: Fuel pressure regulator (pump suction control valve) circuit low.

Engine and gearbox (powertrain) · Costly if missed

Usual causes, most likely first

wiring short
failed SCV
corroded plug

P0091 by make

Isuzu

Fuel pressure regulator (pump suction control valve) circuit low.

Usual causes: wiring short; failed SCV; corroded plug

Mazda

Direct injection high pressure fuel pump control circuit low. PCM stops pump control and limits intake air: low power.

Usual causes: high pressure fuel pump solenoid or connector; wiring fault; PCM

Volvo

Fuel pressure regulator control circuit low.

Usual causes: fuel pump control module fault; wiring fault; weak fuel pump

What the repair usually costs

A/C compressor replace incl. drier and flush (European)NZ$1,560–NZ$3,200 · A$1,490–A$3,050
High-pressure fuel pump (GDI petrol or common-rail diesel)NZ$1,140–NZ$4,280 · A$1,060–A$3,800

Not sure what P0091 means on your car? Ask Credov.

Before you clear it

Write the code down or photograph the scanner first. A code that comes straight back after clearing points to a fault that is still there. A car whose codes were cleared just before you arrived may be hiding one: the scanner's readiness monitors show "not ready" for a while after codes are cleared.

Researched by Credov from manufacturer and workshop sources. A fault code points to where a fault may be; a workshop confirms it with a diagnosis. Browse all fault codes.