Fault code P1191 – a step-by-step guide to diagnosing and fixing it

The meaning of error code P1191 – Key Line Voltage

P1191: Causes, signs and repairs

Error code P1191 is displayed and the check engine light is on - what does this mean?

The DTC P1191 is recognized by the OBD/EOBD system when there is a problem with the fuel system pressure regulator or fuel pressure regulation. This manufacturer-specific fault code mainly occurs in Ford vehicles and indicates a malfunction in the fuel supply system.

What can cause this fault code?

Defective fuel pressure regulator
Clogged fuel filter
Faulty fuel pump
Damaged fuel lines
Loose or corroded plug connections on the fuel pressure sensor
Defective fuel pressure sensor
Clogged fuel injectors
Electrical problems in the fuel pump circuit
Faulty fuel pump control unit

What symptoms occur in parallel with fault code P1191?

Starting problems: The vehicle is difficult to start or does not start at all
Loss of power: Significantly reduced engine power while driving
Uneven idling: Engine runs unevenly at idle speed
Jerking: Vehicle jerks when accelerating or while driving
Stalling of the engine: Engine stalls while driving or idling
Increased fuel consumption: Significantly higher fuel consumption than usual
Check Engine Light: Check Engine Light lights up permanently

How can I fix the problem with error code P1191?

Repairing trouble code P1191 requires a systematic diagnosis of the fuel system.
Replace the fuel pressure regulator if it is defective and no longer builds up or maintains the correct pressure
Replace the fuel filter if it is clogged and obstructs the fuel flow
Replace the fuel pump completely if it can no longer generate the required system pressure
Replace and calibrate the fuel pressure sensor if it is transmitting incorrect readings to the control unit
Check all fuel lines and connections for leaks and replace damaged parts
Clean, repair or replace electrical connections and wiring harness of the fuel pump
Clean or replace fuel injectors if they are blocked by dirt
Check fuel pump relays and fuses and replace if necessary

FAQ - Frequently asked questions about DTC P1191

Can I continue driving with error code P1191?

Continuing to drive with error code P1191 is not recommended, as problems with the fuel pressure can lead to engine damage. If the symptoms are acute, you should stop the vehicle immediately and have it towed away.

How much does it cost to repair error code P1191?

The repair costs for code P1191 vary depending on the cause: fuel filter replacement costs €50-100, a new fuel pressure regulator costs €150-300, while a fuel pump can cost €300-800. The diagnosis costs €80-120.

Can I repair error code P1191 myself?

Simple work such as changing the fuel filter can be carried out by experienced hobby mechanics. However, work on the fuel pump or pressure regulator requires special tools and expertise, which is why a workshop is recommended.

How long does it take to repair P1191?

The repair time depends on the cause: Replacing a fuel filter takes 1-2 hours, while replacing a fuel pump can take 3-6 hours. Diagnosis takes an additional 1-2 hours.

Does the error code P1191 occur frequently?

DTC P1191 is a manufacturer-specific code that mainly occurs in Ford vehicles. It is one of the more common fuel system fault codes, especially in older vehicles with high mileage.

What happens if I ignore P1191?

Ignoring the P1191 fault code can lead to serious engine damage as incorrect fuel pressure affects combustion. This can result in catalytic converter damage, valve damage or even engine damage.

Vehicles in which error code P1191 occurs most frequently

Fault code P1191 is a manufacturer-specific trouble code that mainly indicates problems with the fuel pressure system and can lead to significant driving problems, but is most common in the following vehicles:

Ford: Focus, Fiesta, Mondeo, Escort, Ka, Puma (1995-2010)
Mazda: 323, 626, Premacy, Demio (1996-2008)
Volvo: S40, V40, S60, V70 (1997-2005)
Jaguar: X-Type, S-Type (2001-2009)
Land Rover: Freelander, Discovery (1998-2006)

If the code P1191 occurs in your vehicle, you should first have a professional OBD diagnosis carried out to determine the exact cause. As this is a fuel system-related problem, prompt repair is important to avoid consequential damage to the engine. Most problems can be rectified by replacing the fuel pressure regulator or fuel pump, but a full system check should always be carried out.

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