Cylinder 7 Injector Circuit Low
The P0279 code indicates that the Engine Control Module (ECM) has detected a low voltage or resistance condition in the electrical circuit for the fuel injector on cylinder 7. This typically means the injector's electrical circuit is shorted to ground, has excessive resistance, or the injector itself is faulty. The ECM monitors the injector driver circuit and sets this code when the voltage is below the expected threshold during operation.
1. Most Common Causes
- Fuel injector for cylinder 7 is internally shorted or damaged
- Injector circuit wiring shorted to ground
- Loose, corroded, or oxidized electrical connection at the injector connector
- Open circuit in the injector power or control wiring
- Internal failure of the injector driver within the PCM/ECM
- Damaged injector power supply fuse or relay
2. Symptoms You Will Notice
- Engine misfire on cylinder 7
- Rough idle or hesitation
- Check Engine Light illuminated
- Poor fuel economy
3. Step-by-Step Diagnosis
Step 1: Scan for codes and verify P0279 is present.
Step 2: Visually inspect the injector connector and wiring for damage or corrosion.
Step 3: Measure resistance of cylinder 7 injector; compare to specification (typically 12-16 ohms).
Step 4: Check for voltage at the injector connector with key on; should be battery voltage on one pin.
Step 5: Perform a injector balance test or use a noid light to confirm injector pulse.
Step 6: If wiring and injector check out, test the ECM output or swap injectors to isolate the issue.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive with this code as it can cause engine misfire, reduced performance, and potential damage to the catalytic converter.
How much does it cost to fix?▼
The cost typically ranges from $150 to $400, including parts and labor, depending on whether the injector or wiring needs replacement.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.