DTC Code P0279 – What does this code mean?

<ul> <li><b>Engine Light ON (or Service Engine Soon Warning Light)</b>: The engine control unit (ECU) detects an issue with the injector control circuit for cylinder 7, triggering the warning light. <causes> could include a faulty injector, wiring issues, or a malfunctioning ECU.</li> <li><b>Engine Misfire</b>: A misfire in cylinder 7 can occur due to insufficient fuel delivery caused by low voltage in the injector control circuit. <causes> may involve a defective injector, poor electrical connections, or a failing ECU.</li> <li><b>Engine Run Rough</b>: The engine may run rough as cylinder 7 fails to receive the proper amount of fuel. <causes> could be a damaged injector, wiring problems, or an issue with the ECU.</li> <li><b>Low MPG</b>: Fuel efficiency may decrease as the engine compensates for the misfire and rough running condition. <causes> include a malfunctioning injector, electrical issues, or a faulty ECU.</li> </ul>

<ul><li>Dirty fuel injector 7 can cause improper fuel delivery, leading to low voltage in the control circuit.</li><li>A faulty fuel injector 7 may not operate correctly, resulting in low voltage signals.</li><li>A plugged fuel injector 7 can restrict fuel flow, affecting the injector's performance and voltage.</li><li>An open or shorted harness for fuel injector 7 can disrupt the electrical connection, causing low voltage.</li><li>Poor electrical connections in the fuel injector 7 circuit can lead to intermittent or low voltage signals.</li><li>A faulty Engine Control Module (ECM) may fail to properly control the injector, resulting in low voltage readings.</li></ul>

<ul> <li><b>Initial Scan</b>: Use an OBD-II scanner to confirm the presence of DTC P0279 and check for any additional codes.</li> <li><b>Visual Inspection</b>: Inspect the wiring and connectors related to Cylinder 7 injector for any signs of damage, corrosion, or disconnection.</li> <li><b>Injector Flush</b>: Perform an injector flush to clean any potential clogs in the fuel injector. This can often resolve the issue without the need for replacement.</li> <li><b>Voltage Test</b>: Use a multimeter to measure the voltage at the injector connector. Ensure the voltage is within the manufacturer's specified range.</li> <li><b>Continuity Test</b>: Check the continuity of the injector control circuit from the Engine Control Module (ECM) to the injector. Repair any open or short circuits found.</li> <li><b>Injector Resistance Test</b>: Measure the resistance of the injector coil. Compare the reading to the manufacturer's specifications to determine if the injector is faulty.</li> <li><b>ECM Test</b>: If all previous tests are normal, test the ECM for proper operation. Replace the ECM if it is found to be defective.</li></ul>

<p>The DTC code P0279 indicates a low voltage issue in the Cylinder 7 Injector Control Circuit. This is a critical issue as it can lead to engine misfires, poor performance, and potential engine damage.</p><ul><li><b>Immediate Actions:</b> Inspect the injector wiring and connectors for damage or corrosion.</li><li>Check the injector itself for proper operation.</li><li>Test the power supply to the injector circuit.</li></ul><p>Delaying repair can result in severe engine damage and increased repair costs.</p>