P0291 Fault Code

P0291 OBD-II Trouble Code Short Description

Cylinder 11 Injector Circuit Low

What does trouble code P0291 mean?

The P0291 fault code refers to an issue with the cylinder 11 injector circuit in the engine. This code indicates that the circuit is experiencing a low voltage or resistance, which can lead to a decrease in fuel delivery to that specific cylinder.

There are a few possible reasons for this error code. It could be due to a wiring issue, such as a short or open circuit in the injector wiring harness. Another possibility is a faulty fuel injector itself, which may be clogged or malfunctioning.

To diagnose and fix this issue, a few steps can be taken. First, a technician will likely perform a visual inspection of the injector wiring and connectors to check for any obvious faults. They may also use a multimeter to measure the voltage and resistance in the circuit.

If a wiring issue is found, it can be repaired or replaced as necessary. In the case of a faulty injector, it may need to be cleaned or replaced to restore proper fuel delivery to cylinder 11.

It's important to address this code promptly as it can affect the engine's performance and fuel efficiency. Additionally, running the engine with a cylinder receiving insufficient fuel can cause damage over time.

Overall, the P0291 fault code indicates a problem with the cylinder 11 injector circuit. Proper diagnosis and repair by a qualified technician are crucial to resolve this issue and ensure the engine operates smoothly and efficiently.


What are the symptoms of the P0291 code?

The P0291 fault code indicates a problem with the injector circuit in cylinder 11. Symptoms of this fault code may vary depending on the specific car model, but commonly reported symptoms include:

  • Engine misfire or rough idle
  • Decreased engine performance and power
  • Poor fuel efficiency
  • Check Engine Light (CEL) illuminated
  • Hard starting or difficulty in starting the engine
  • Stalling or hesitation during acceleration

If you are experiencing any of these symptoms, it is recommended to have your vehicle diagnosed and repaired by a qualified mechanic to resolve the issue related to the Cylinder 11 Injector Circuit Low error code.


What causes the P0291 code?

The P0291 fault code indicates a problem with the cylinder 11 injector circuit being detected as low. This can be caused by the following issues:

  1. Faulty injector: A malfunctioning or clogged fuel injector can result in insufficient fuel delivery to the respective cylinder.

  2. Wiring or connector problems: Damage or loose connections in the wiring harness or connectors between the injector and the PCM (Powertrain Control Module) can cause low voltage signals and trigger the fault code.

  3. Fuel system issues: A restricted fuel filter, fuel pump failure, or fuel pressure regulator malfunction can lead to low fuel pressure, affecting the injector operation.

  4. Engine control module (ECM) failure: A faulty ECM may not be providing the correct voltage or control signals to the cylinder 11 injector circuit.

To diagnose and resolve the P0291 fault code, it is recommended to perform the following steps:

  1. Inspect the injector and fuel delivery system: Check for any signs of leakage, clogging, or damage. Ensure proper fuel pressure and flow rate.

  2. Inspect the wiring and connectors: Examine the wiring harness and connectors for any visible damage or loose connections. Repair or replace as necessary.

  3. Test the injector: Use an injector tester to check the electrical resistance and operation of the cylinder 11 injector. Replace if faulty.

  4. Scan for additional codes: Check for any other related fault codes and address them accordingly.

  5. Evaluate the ECM: If all other components are functioning properly, consider testing or replacing the ECM if it is suspected to be the cause of the fault.

It is recommended to consult the vehicle's service manual or seek assistance from a certified mechanic for a proper diagnosis and resolution of the P0291 fault code.

Possible Solutions

How to fix P0291?

To fix the P0291 fault code, which refers to the Cylinder 11 Injector Circuit Low, follow these steps:

  1. Check the injector wiring harness:

    • Inspect the wiring harness connected to cylinder 11 injector for any signs of damage, loose connections, or corrosion.
    • Repair or replace any damaged or faulty wiring as necessary.
  2. Inspect the injector connector:

    • Disconnect the injector connector and visually inspect it for any bent or corroded pins.
    • Clean the connector if any corrosion is present.
    • Replace the connector if any pins are bent or damaged.
  3. Verify proper voltage supply:

    • Use a multimeter to check the voltage supply to the injector.
    • The voltage should be within the manufacturer's specified range.
    • If the voltage is too low or unstable, check the power supply to the injector for any issues and repair as necessary.
  4. Check the injector resistance:

    • Measure the resistance of the injector using an ohmmeter.
    • Compare the reading to the manufacturer's specifications.
    • If the resistance is too high or too low, replace the faulty injector.
  5. Inspect the fuel system:

    • Check the fuel system for any clogs or restrictions.
    • Inspect the fuel filter, fuel lines, and fuel pump.
    • Replace or repair any components that are causing fuel delivery issues.
  6. Perform an engine management system scan:

    • Use a diagnostic scan tool to perform an engine management system scan.
    • Look for any additional fault codes that may indicate other related issues.
    • Address any additional issues found during the scan.
  7. Clear the fault codes and test drive:

    • Once all necessary repairs have been made, clear the fault codes using the scan tool.
    • Take the vehicle for a test drive to ensure the P0291 fault code does not return.

If the fault code persists after following these steps, it is recommended to consult a professional mechanic or dealership for further diagnosis and repair.