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P0086 Code – What Does It Mean & How To Fix It

This is one of the most frequent OBD2 trouble codes. Read the full article below to know what it means, how to fix it, and what other codes may show related to it.


P0086 stands for “fuel rail system pressure too high” and is a specific DTC. This code shall be triggered when the engine control module ECM detects that there is an increase in fuel pressure in a fuel rail or fluid system beyond the manufacturer’s defined limits.


In order to ensure optimum engine performance, the fuel pressure in the fuel system must be kept within an appropriate range. When the pressure increases too much, there could be a variety of problems, such as fuel injection failures, engine misfires, and potential damage to components in the fuel system.


  • Fuel pressure regulator issue: A faulty fuel pressure regulator can result in high fuel pressure and the appearance of the P0086 error code.
  • Fuel filter clog: A blocked fuel filter can restrict fuel flow and cause the fuel system’s pressure to rise.
  • Defective Fuel Pump: A failing fuel pump may supply too much fuel to the system, resulting in high fuel pressure readings.
  • Fuel Return Line Restriction: If the fuel return line is kinked or clogged, the fuel cannot flow back to the fuel tank properly, which increases pressure.


  • Check engine light: The illumination of the check engine light on the vehicle’s dashboard is the most common symptom of P0086. 
  • Problems with engine performance: A driver may feel rough idle, hesitation at the start of acceleration, or a decrease in overall engine efficiency. 
  • Reduction in fuel efficiency: Due to a mismatch between the ratio of air and oil, excess pressure on energy may lead to poor fuel economy.


The following actions will be taken by a skilled technician to diagnose the P0086 code:

  • OBD-II Scanner: To extract the particular code and any associated codes recorded in the vehicle’s ECM, the technician will utilize an OBD-II scanner.
  • Visual Inspection: The components of the fuel system will be carefully inspected visually to look for any obvious evidence of damage or leakage.
  • Fuel Pressure Test: A fuel pressure gauge will be used to test the fuel system’s pressure to see if it is within the suggested range.

Common mistakes

  •  Replacement without a diagnosis: to avoid unnecessary costs, it is necessary to carry out a full diagnostic examination before any parts are replaced. 
  • Ignoring associated codes: It is common for the ECM to contain other relevant codes, which may yield valuable information on the root cause of an issue.

How serious is this?

The nature of the P0086 code is determined by the cause and extent of the problem. If this code is still missing, continuing to drive with it may result in additional engine damage or decreased performance and should be addressed without delay.

What repairs can fix the code?

repair manuals

  • Replace the Fuel Pressure Regulator: In order to ensure that the fuel pressure is kept within a proper range, it should be replaced if the regulator is not functioning properly. Clean and replace the Fuel Filter: If your fuel filter is dirty, it should be cleaned or changed in order to restore the correct flow of fuel. 
  • Replacing or repairing the fuel pump: In order to ensure the correct fuel supply for your engine, it is recommended that a malfunctioning fuel pump be fixed or refitted.
  • Check the Fuel Return Line: The fuel return line should be inspected for any obstructions or damage and repaired as necessary.

Related codes

P0087 (Fuel Rail/System Pressure – Too Low): This code indicates the opposite problem, where the fuel pressure is too low.


For example, the DTC code P0086 indicates that there is too much fuel pressure in the system and this could lead to problems with engine performance. It is essential that a diagnosis be carried out promptly and accurately so as to determine the root of the problem and make necessary repairs.

If you find this code in your vehicle, the best thing to do is hire a qualified professional mechanic who will be able to diagnose it quickly and ensure its optimal operation. Regular maintenance and timely repairs are essential for the longevity and performance of your vehicle’s fuel system and engine.

P0086 Code – What Does It Mean & How To Fix It