WOMS
P code powertrain Medium severity

P0291 Cylinder 11 Injector Circuit Low

The OBD2 code P0291 indicates a low voltage or malfunction in the injector circuit for cylinder 11, suggesting that the fuel injector is not receiving the proper electrical signal or is not functioning correctly

Definition

The OBD2 code P0291 indicates a low voltage or malfunction in the injector circuit for cylinder 11, suggesting that the fuel injector is not receiving the proper electrical signal or is not functioning correctly

Common causes

  • Faulty injector
  • Wiring issues (shorts or open circuits)
  • Poor electrical connections
  • Faulty engine control module (ECM)
  • Fuel delivery problems
  • Grounding issues
  • Injector driver circuit failure

Common misdiagnoses

  • Faulty fuel injector
  • Wiring issues or short circuits
  • Engine control module (ECM) failure
  • Fuel delivery problems
  • Vacuum leaks
  • Faulty fuel pump
  • Injector driver circuit issues
  • Low fuel pressure
  • Engine misfire
  • Faulty ignition components

Troubleshooting steps

  1. 1. Check for Additional Codes

    Before proceeding, check for any other trouble codes that may be present. This can provide more context about the issue

  2. 2. Visual Inspection

  3. 3. Inspect the wiring and connectors associated with the injector for cylinder 11. Look for signs of damage, corrosion, or loose connections

  4. 4. Check the injector itself for any physical damage or signs of fuel leakage

  5. 5. Test the Injector

  6. 6. Use a multimeter to measure the resistance of the injector. Compare the reading to the manufacturer's specifications. A significantly low or high resistance could indicate a faulty injector

  7. 7. If possible, swap the injector with another cylinder to see if the code follows the injector. If it does, the injector is likely faulty

  8. 8. Check the Injector Circuit

  9. 9. With the engine off, check the voltage at the injector connector. You should see battery voltage (typically around 12V) when the ignition is on

  10. 10. If the voltage is low or absent, trace the wiring back to the engine control module (ECM) to check for shorts, opens, or other issues

  11. 11. Inspect the Engine Control Module (ECM)

  12. 12. If the wiring and injector are in good condition, the issue may lie with the ECM. Check for any signs of damage or corrosion on the ECM connectors

  13. 13. If you have access to a scan tool, check for any ECM-related issues or updates

  14. 14. Check for Ground Issues

  15. 15. Ensure that the injector has a good ground connection. A poor ground can cause low voltage readings. Use a multimeter to check the ground continuity

  16. 16. Test the Fuel System

  17. 17. Ensure that the fuel system is functioning properly. Low fuel pressure can sometimes cause injector issues. Check the fuel pump and fuel pressure regulator

  18. 18. Clear the Code and Test Drive

  19. 19. After performing the necessary repairs or checks, clear the code using an OBD-II scanner and take the vehicle for a test drive to see if the code returns

  20. 20. Consult a Professional

    If the issue persists after performing these steps, it may be best to consult a professional mechanic or technician who has experience with your specific vehicle make and model. By following these steps, you should be able to identify and resolve the issue related to the P0291 code