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P0003 OBD Fault Code (Causes & Fixes)

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Last Updated on: 7th September 2023, 12:44 am

A P0003 DTC code relates to the electrical circuit that connects to your fuel pressure regulator.

Fault CodeFault LocationProbable Cause
P0003Fuel volume regulator control -circuit lowWiring short (to earth), regulator control solenoid

P0003 is a generic OBD code that indicates a problem with your engine’s engine control module (ECM) receiving signals from your fuel pressure regulator on your fuel injection rail.

The code may have an impact on fuel efficiency and may even cause engine damage.

It may potentially be linked to the following codes; P0001, P0002, or P0004.

The definition of this trouble code is: “fuel volume regulator control -circuit low”, the probable cause is either shorting to earth or the regulator control solenoid.

What P0003 Means

The electrical circuit that connects to your fuel pressure regulator is connected with the P0003 code.

It’s a generic OBD code that means the engine control module (ECM) is having trouble receiving signals from your fuel pressure regulator on your fuel injection rail.

The ECM takes information on your actual fuel pressure from the fuel pressure sensor and controls your fuel pressure from your fuel pump flowing to your engine via this circuit.

When the computer senses that it is not commanding enough fuel pressure to the fuel pump, it will illuminate the check engine light (MIL) and generate this fault code.

The issue may have an impact on fuel efficiency and may even cause engine damage.

Possible Causes

There are various reasons for a low code in the fuel volume regulator control circuit, such as the following.

  • Corrosion in the sensor connection or wiring is a possibility
  • The sensor connecting to the ECM has a short (to earth)
  • The fuel pressure regulator is broken
  • The ECM has been damaged

This failure code might also be caused by different systems and components connected to the fuel system which is why it needs to be properly diagnosed.

This code and many other DTCs might be caused by excessive heat, normal wear and tear, vibrations, shock and impacts (from potholes, for example), rubbing and friction, corrosion, and so on.

Signs & Symptoms

A P0003 code usually causes the check engine light (MIL) to illuminate on the instrument panel/dashboard, and it is likely to have the following effects.

  • Reduced performance of the engine
  • Fuses that have blown
  • ECM deterioration
  • While driving, there’s a chance you’ll stall
  • It may cause black or white smoke to appear in the exhaust
  • Reduced fuel efficiency
  • Damaged catalytic converter


The cause of this fault code can have multiple risks for your vehicle, including the following.

  1. Reduce overall fuel economy
  2. Cause fuel instability, which may lead to severe engine damage
  3. The catalytic converters will be harmed
  4. Negatively affecting your ECM
  5. The electrical harness is damaged
  6. Increase emissions


Any sensor problem might happen all of the time or just on occasion. Some error codes may take longer to diagnose than others.

The remedy for this code might be easy to change or take a long time to diagnose and correct.

Depending on your car, determining the underlying cause and repairing the defective component might take several hours.

Usually it is best to have this error diagnosed by a professional technician.

A sophisticated OBD scan tool capable of factory sensor readings is used to correctly diagnose P0003 (not just one from an auto parts store).

The data from the advanced scan tool may be reviewed by a competent technician to establish when the issue first started and whether it is still happening.

They may clear the code/light and test drive the vehicle while keeping an eye on the scan tool data to see whether the problem reappears or if it is still there.

Cutting open the protective covering, checking the wiring and harness, and reinstalling the covering may be required to examine the wiring for damage.

Further diagnostic work may be necessary based on the circumstances, maybe clearing the code, and a road test while monitoring the data.

Multiple tools may be required for diagnosis, such as the following.

  • A sophisticated scan tool
  • A digital voltage metre
  • Fuel pressure gauge

How to Fix

Below is the process most automotive technicians will follow in order to fix the P0003 error code.

  1. Connect a professional scan tool and check to see whether the code exists.
  2. Check for any additional fault codes that could be connected to the problem, then clear them to see which ones come back.
  3. Analyse data from the ECM scan tool.
  4. With additional equipment connected, road test the car while reviewing scan tool data from the ECM.
  5. Check to see whether the P0003 error code appears.
  6. Examine all of the likely culprits (wiring, voltages, etc).
  7. If the problem seems to be recurring, use the specific tools described above to further diagnose the issue. The sensor’s signals and wiring must be analysed to pinpoint the source of the issue. If the indications are normal, further examination of the wiring, computer, or fuel system is necessary.
  8. Replace the fuel pressure regulator, wiring, ECM (and reprogramming if required), or anything else if it’s broken.
  9. Make repairs if required.

The P0003 code affects a number of systems and requires a thorough investigation.

A technician might establish whether the fuel pressure regulator, wiring, or ECM is at fault after utilising a scan tool and watching the voltage data.

With the scan tool attached, assess the data while checking the voltage metre to confirm that all of the numbers are correct and that the circuit is free of shorts.

If no voltage is stated, a more thorough examination is necessary.

The sensor might be the problem, or you could have a poor ECM as a result of the short.

Wiring could also be the culprit, or rodents and pests could have eaten through wiring somewhere in the car, connections could have shorts or damage, or you could have a defective ECM as a result of the short.

It is necessary to use an advanced scan tool with specialist instruments for examination.

You may clear the code/light first, then see if the check engine light comes back on and continue to troubleshoot. It may have been a one-time incidence, or it could have been a long-term issue.

Higher-mileage vehicles (80,000+ miles) may just need a fuel pressure regulator replacement.

For additional precise troubleshooting instructions for your year, make, model, and engine, see a manufacturer service manual.

  • Andy Lewin

    Andy Lewin is a senior mechanic, ASE qualified master technician, and an experienced automotive engineer.He's passionate about serving the automotive community with the highest-quality and trustworthy information on all things automotive. He loves to write about car repairs, maintenance, car modifications and tuning, faults, and much more.

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