P0279 Fault Code

P0279 OBD-II Trouble Code Short Description

Cylinder #7 Injector Circuit Low

What does trouble code P0279 mean?

The P0279 fault code refers to a problem in the fuel injector circuit of cylinder #7 in the engine. This code indicates that the voltage or current in the circuit is lower than the expected level.

There are several potential causes for this issue, including a faulty fuel injector, wiring problems, or a problem with the engine control module (ECM).

To diagnose and solve this problem, the following steps can be taken:

  1. Inspect the wiring harness and electrical connectors: Check for any signs of damage, corrosion, or loose connections in the wiring associated with cylinder #7 injector. Repair or replace any damaged parts as necessary.

  2. Test the injector resistance: Use a multimeter to measure the resistance of the injector. Compare the result with the manufacturer's specifications. If the resistance is outside the acceptable range, the injector may be faulty and need replacement.

  3. Check the fuel injector driver circuit: Test the circuitry responsible for controlling the fuel injector. This involves examining the ECM, connectors, and associated components for any faults. If any issues are detected, they should be addressed accordingly.

  4. Perform an ECM reset and reprogramming: In some cases, resetting the ECM and reprogramming it with the latest software updates may resolve the issue. This step should be taken after inspecting and repairing any physical or electrical faults.

It is crucial to address the P0279 fault code promptly as a malfunctioning injector can lead to engine misfires, reduced performance, and even damage to the catalytic converter. If you're not experienced in automotive repair, it's recommended to seek assistance from a professional technician who can properly diagnose and resolve the issue.


What are the symptoms of the P0279 code?

  • Engine misfire: The cylinder #7 may not be receiving enough fuel, causing it to misfire.
  • Rough idling: The engine may idle roughly or may even stall due to the injector circuit malfunction.
  • Reduced power and acceleration: The vehicle may experience a loss of power and reduced acceleration capability.
  • Decreased fuel efficiency: Due to an insufficient fuel supply to cylinder #7, the engine may consume more fuel than usual.
  • Check Engine Light: The malfunctioning injector circuit will trigger the check engine light to illuminate on the dashboard.
  • Fuel odor: In some cases, a fuel odor may be present due to an imbalance in the fuel-to-air mixture.


What causes the P0279 code?

The P0279 fault code on cars indicates a problem with the Cylinder #7 Injector Circuit Low. Here are some possible causes for this fault code:

  1. Faulty cylinder #7 fuel injector: The fuel injector may be malfunctioning, resulting in a low circuit voltage. This could be due to a clogged or dirty fuel injector.

  2. Wiring or connector issues: There may be a problem with the wiring harness or connector that connects the fuel injector to the vehicle's electrical system. Wiring damage or poor connections can lead to a low circuit voltage.

  3. Injector driver circuit problem: The injector driver circuit, which controls the fuel injection process, could be faulty. This could be caused by a defective fuel injector control module or a problem with the engine control unit (ECU).

  4. Fuel delivery issues: If there are problems with fuel delivery to the cylinder #7 injector, such as a restricted fuel line or a faulty fuel pump, it can result in a low circuit voltage.

  5. Other possible causes: Other potential factors contributing to the P0279 fault code include a faulty ECU, a malfunctioning fuel pressure regulator, or issues with the fuel system's electrical supply.

It is recommended to have a qualified mechanic diagnose and repair the underlying cause of the fault code to prevent further engine damage and ensure optimal vehicle performance.

Possible Solutions

How to fix P0279?

To fix the P0279 fault code on cars, follow these steps:

  1. Check the wiring: Inspect the wiring harness for any visible damage or loose connections. Repair or replace any damaged wires and ensure all connections are secure.

  2. Inspect the injector: Remove and inspect the injector for any clogs or damage. Clean or replace the injector if necessary.

  3. Test the injector: Use a digital multimeter to test the injector resistance. Compare the readings to the manufacturer's specifications. Replace the injector if the resistance is outside the acceptable range.

  4. Check the fuel pressure: Use a fuel pressure gauge to measure the fuel pressure. Ensure it meets the manufacturer's specified range. If the pressure is too low, it may indicate a problem with the fuel pump or fuel filter.

  5. Inspect the fuel system: Check for any restrictions or blockages in the fuel lines. Ensure the fuel filter is clean and not clogged. Replace any faulty components.

  6. Test the fuel delivery: Use a fuel injector tester to check the fuel delivery from the injector. If the fuel delivery is insufficient, the injector may need to be replaced.

  7. Check the ECM: If all other components are in working order, there may be a problem with the Engine Control Module (ECM). Consider having the ECM tested or replaced, if necessary.

  8. Clear the fault codes: After making any repairs, use an OBD-II scanner to clear the fault codes. Take the vehicle for a test drive to ensure the P0279 code does not reappear.

Note: It is recommended to consult the vehicle's service manual or seek professional assistance for a more accurate diagnosis and repair process.