Engine-CodesGMC – P1231 GMC

P1231 GMC Code - Injector Circuit Cylinder 4 Intermittent

Quick Answer

The P1231 code for GMC vehicles indicates an issue with the injector circuit for cylinder 4 that is intermittent. Common causes include Faulty fuel injector in cylinder 4, Wiring issues in the injector circuit, Poor connection or corrosion in the wiring harness. 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
P1231 GMC indicates Injector Circuit Cylinder 4 Intermittent.
Common causes
Common causes include Faulty fuel injector in cylinder 4, Wiring issues in the injector circuit, Poor connection or corrosion in the wiring harness.
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.
Table of contents Created and updated by William Orellana on Sep 08, 2024
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Code P1231 GMC Description

The P1231 code for GMC vehicles indicates an issue with the injector circuit for cylinder 4 that is intermittent. This means that there is a problem with the fuel injector in the fourth cylinder that is not consistently functioning properly. The fuel injector is responsible for delivering the right amount of fuel into the combustion chamber at the correct time. When this process is disrupted, it can lead to a variety of performance issues in the vehicle.

OBDII Code P1231 GMC - Injector Circuit Cylinder 4 Intermittent
P1231 GMC Code - Injector Circuit Cylinder 4 Intermittent

Common Causes of P1231 GMC

  1. Faulty fuel injector in cylinder 4
  2. Wiring issues in the injector circuit
  3. Poor connection or corrosion in the wiring harness
  4. Problem with the engine control module (ECM)
  5. Fuel delivery issues such as a clogged fuel filter or low fuel pressure

Symptoms of P1231 GMC

  1. Misfires in cylinder 4
  2. Rough idling or vibrations while the engine is running
  3. Decreased fuel efficiency
  4. Engine stalling or hesitation
  5. Check Engine Light illuminated on the dashboard

How to Fix P1231 GMC

  1. Begin by diagnosing the specific cause of the issue by conducting a thorough inspection of the fuel injector, wiring, and connections.
  2. Test the fuel injector in cylinder 4 to determine if it is functioning correctly or needs to be replaced.
  3. Inspect the wiring harness for any damage, corrosion, or poor connections and repair or replace as necessary.
  4. Check the engine control module (ECM) for any faults or errors and reprogram or replace if needed.
  5. Clear the diagnostic trouble codes, perform a test drive to ensure the issue has been resolved, and reset the Check Engine Light.

Cost to Fix P1231 GMC

The typical repair costs for addressing the P1231 code for GMC vehicles can range from $150 to $500, depending on the specific cause of the issue and the labor rates at the auto repair shop. The cost may vary based on factors such as location, vehicle make and model, and engine type. It is recommended to inquire about local rates for a more precise estimate before proceeding with the repair.

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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.

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