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P code powertrain High severity

P1273 Cylinder #3 High To Low Side Open

The OBD2 code P1273 indicates that there is an open circuit or high resistance in the sensor circuit for cylinder #3, affecting the signal between the sensor and the engine control module (ECM)

Definition

The OBD2 code P1273 indicates that there is an open circuit or high resistance in the sensor circuit for cylinder #3, affecting the signal between the sensor and the engine control module (ECM)

Common causes

  • Faulty fuel injector for cylinder #3
  • Open or shorted wiring in the injector circuit
  • Poor electrical connection or corroded terminals
  • Faulty engine control module (ECM)
  • Failed or damaged fuel injector driver circuit
  • Vacuum leak affecting cylinder #3
  • Faulty fuel rail or fuel delivery issues
  • Malfunctioning ignition system affecting cylinder #3

Common misdiagnoses

  • Faulty fuel injector
  • Wiring issues or shorts
  • Faulty engine control module (ECM)
  • Vacuum leaks
  • Faulty ignition coil
  • Fuel delivery problems
  • Faulty sensors (e.g., MAF, MAP)
  • Injector driver circuit issues

Troubleshooting steps

  1. 1. Check for Additional Codes

    Use an OBD-II scanner to check for any other trouble codes that may be present. This can provide more context and help identify related issues

  2. 2. Inspect the Wiring and Connectors

    Visually inspect the wiring harness and connectors for cylinder #3. Look for signs of damage, such as frayed wires, corrosion, or loose connections

  3. 3. Ensure that the connector is securely attached to the fuel injector

  4. 4. Test the Fuel Injector

    Use a multimeter to check the resistance of the fuel injector. Compare the reading to the manufacturer's specifications. A reading that is too high or too low may indicate a faulty injector

  5. 5. If possible, swap the injector with another cylinder to see if the code follows the injector

  6. 6. Check the Power and Ground

    With the ignition on (engine off), use a multimeter to check for voltage at the fuel injector connector. You should see battery voltage (typically around 12V)

  7. 7. Check the ground side of the injector circuit. Ensure that the ground is solid and that there is continuity to the ECM

  8. 8. Inspect the ECM

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

  9. 9. If possible, test the ECM with a known good unit to see if the problem persists

  10. 10. Check for Short Circuits

    Inspect the wiring for any potential short circuits to ground or to other wires. Use a multimeter to check for continuity between the injector circuit and ground

  11. 11. Clear the Codes and Test Drive

    After performing any repairs, clear the trouble codes using the OBD-II scanner and take the vehicle for a test drive to see if the code returns

  12. 12. Consult Repair Manual

    If the issue persists, consult the vehicle's repair manual for specific diagnostic procedures and specifications related to the fuel injector circuit

  13. 13. Seek Professional Help

    If you are unable to resolve the issue after following 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 troubleshooting steps, you should be able to identify and resolve the issue related to the P1273 code