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Engine-Codes – GMC – P0279 GMC

P0279 GMC Code - Cylinder 7 Injector Control Circuit Low Voltage

Quick Answer

The diagnostic trouble code P0279 for GMC vehicles indicates a problem with the Cylinder 7 Injector Control Circuit having low voltage. Common causes include Faulty fuel injector for cylinder 7, Wiring issues or short circuits in the injector control circuit, Corrosion or poor connections in the electrical system. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means
P0279 GMC indicates Cylinder 7 Injector Control Circuit Low Voltage.
Common causes
Common causes include Faulty fuel injector for cylinder 7, Wiring issues or short circuits in the injector control circuit, Corrosion or poor connections in the electrical system.
Severity
High - diagnose this code as soon as possible.
Can I drive?
Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
What is this?
Table of contents Created and updated by William Orellana on Aug 25, 2024
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Code P0279 GMC Description

The diagnostic trouble code P0279 for GMC vehicles indicates a problem with the Cylinder 7 Injector Control Circuit having low voltage. This code suggests that there is an issue with the fuel injector for cylinder 7, specifically with the electrical circuit that controls it. The fuel injector is responsible for delivering the right amount of fuel into the combustion chamber for proper engine operation. When the control circuit voltage is too low, it can lead to a lean fuel mixture, misfires, rough idle, and ultimately, poor engine performance.

OBDII Code P0279 GMC - Cylinder 7 Injector Control Circuit Low Voltage
P0279 GMC Code - Cylinder 7 Injector Control Circuit Low Voltage

Common Causes of P0279 GMC

  1. Faulty fuel injector for cylinder 7
  2. Wiring issues or short circuits in the injector control circuit
  3. Corrosion or poor connections in the electrical system
  4. ECM (Engine Control Module) failure
  5. Fuel delivery issues

Symptoms of P0279 GMC

  1. Engine misfires
  2. Rough idle
  3. Decreased fuel efficiency
  4. Engine stalling
  5. Illumination of the check engine light

How to Fix P0279 GMC

  1. Diagnose the issue by using a scan tool to check for the specific cylinder 7 injector control circuit voltage.
  2. Inspect the wiring and connections for any damage or corrosion, repairing or replacing as needed.
  3. Test the fuel injector for cylinder 7 to ensure it is functioning properly, replacing it if necessary.
  4. Clear the trouble codes and monitor the vehicle's performance to ensure the issue has been resolved.
  5. If the problem persists, further diagnostics may be needed to identify any underlying issues with the ECM or fuel delivery system.

Cost to Fix P0279 GMC

The cost of repairing a Cylinder 7 Injector Control Circuit Low Voltage issue can vary depending on the specific cause of the problem. However, a rough estimate for parts and labor could range from $150 to $500. It's important to note that diagnostic time and labor rates at auto repair shops can fluctuate, so it's advisable to obtain quotes from multiple sources to get a more accurate estimate.

What does this mean?

Tech Notes for P0279 GMC

A clogged or partially clogged fuel injector can cause this code. Start by performing an injector flush before replacing the injector.

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Information for Specific GMC Models

About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about P0279 GMC Code

1. What does the OBDII code P0279 mean on a GMC?

P0279 indicates a low voltage issue in the Cylinder 7 Injector Control Circuit, which can affect the engine's fuel injection system.

2. What are the common symptoms of code P0279 on a GMC?

Symptoms include rough idling, misfires, poor acceleration, reduced fuel efficiency, and in some cases, the engine may fail to start.

3. What causes the P0279 code to appear on a GMC vehicle?

Common causes include a faulty fuel injector, damaged wiring or connectors in the injector circuit, a failing powertrain control module (PCM), or a blown fuse.

4. Can I drive my GMC with a P0279 code?

It is not recommended to drive with this code as it can lead to poor engine performance and potentially cause further damage to the engine or catalytic converter.

5. How do I troubleshoot the P0279 code on my GMC?

Start by inspecting the wiring and connectors for Cylinder 7's injector for damage or corrosion. Use a multimeter to check for proper voltage and continuity in the circuit.

6. How do I fix the P0279 code on a GMC?

Repairs may include replacing the faulty injector, repairing or replacing damaged wiring or connectors, or reprogramming or replacing the PCM if necessary.

7. Can a clogged fuel injector cause the P0279 code?

While a clogged injector typically causes performance issues, this code specifically points to an electrical issue. However, it's still worth inspecting the injector for clogs as part of the diagnostic process.

8. How much does it cost to repair a P0279 code on a GMC?

Costs vary depending on the issue. Replacing a fuel injector may cost $200–$400, while repairing wiring could be less expensive. PCM replacement can exceed $500.

9. Can a bad PCM cause the P0279 code?

Yes, a malfunctioning PCM can fail to properly control the injector circuit, leading to this code.

10. Is a scanner required to diagnose the P0279 code on a GMC?

Yes, an OBDII scanner is necessary to read the code and monitor live data to pinpoint the issue in the injector circuit.

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