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P2C18 2021 GMC Sierra Code - Exhaust Camshaft Profile Actuator Position Sensor 2 Circuit Low Voltage

Quick Answer

The P2C18 code indicates a low voltage condition in the Exhaust Camshaft Profile Actuator Position Sensor 2 circuit. Common causes include Faulty Exhaust Camshaft Profile ActuatorExhaust Camshaft Profile Actuator harness is open or shortedPoor electrical connection in the Exhaust Camshaft Profile Actuator circuitFaulty Engine Control Module (ECM)Mechanical issues such as sticking actuator pins or debris in the actuator assembly. 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
P2C18 2021 GMC Sierra indicates Exhaust Camshaft Profile Actuator Position Sensor 2 Circuit Low Voltage.
Common causes
Common causes include Faulty Exhaust Camshaft Profile ActuatorExhaust Camshaft Profile Actuator harness is open or shortedPoor electrical connection in the Exhaust Camshaft Profile Actuator circuitFaulty Engine Control Module (ECM)Mechanical issues such as sticking actuator pins or debris in the actuator assembly.
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 May 31, 2026
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Code P2C18 2021 GMC Sierra Description

The P2C18 code indicates a low voltage condition in the Exhaust Camshaft Profile Actuator Position Sensor 2 circuit. This sensor is critical for the operation of the exhaust camshaft profile actuator, which adjusts the camshaft's position to optimize engine performance and efficiency. The actuator uses a variable-lift system that allows the engine to adapt its valve lift strategy based on various operating conditions, such as load and RPM. By providing feedback to the Engine Control Module (ECM) about the position of the actuator pins, the sensor ensures that the camshaft can switch between different profiles effectively.
OBDII Code P2C18 2021 GMC Sierra - Exhaust Camshaft Profile Actuator Position Sensor 2 Circuit Low Voltage
P2C18 2021 GMC Sierra Code - Exhaust Camshaft Profile Actuator Position Sensor 2 Circuit Low Voltage

Common Causes of P2C18 2021 GMC Sierra

  1. Faulty Exhaust Camshaft Profile Actuator
  2. Exhaust Camshaft Profile Actuator harness is open or shorted
  3. Poor electrical connection in the Exhaust Camshaft Profile Actuator circuit
  4. Faulty Engine Control Module (ECM)
  5. Mechanical issues such as sticking actuator pins or debris in the actuator assembly

Symptoms of P2C18 2021 GMC Sierra

  1. Engine Light ON (or Service Engine Soon Warning Light)
  2. Reduced engine performance, including sluggish acceleration
  3. Decreased fuel efficiency
  4. Increased emissions, potentially failing emissions tests
  5. Rough idling or stalling during operation

How to Fix P2C18 2021 GMC Sierra

  1. Perform a visual inspection of the Exhaust Camshaft Profile Actuator and its wiring harness for any signs of damage or wear.
  2. Test the voltage output from the Exhaust Camshaft Profile Actuator Position Sensor to confirm if it is within the specified range.
  3. Check for any open or shorted circuits in the wiring that could be causing the low voltage condition.
  4. If the sensor is faulty, replace the Exhaust Camshaft Profile Actuator Position Sensor.
  5. Clear the fault codes and perform a test drive to ensure the issue is resolved and the engine operates smoothly.

Cost to Fix P2C18 2021 GMC Sierra

The cost to diagnose and repair a P2C18 code typically ranges from $150 to $600, depending on the specific issue and the parts required. Replacing the Exhaust Camshaft Profile Actuator Position Sensor can cost between $100 and $300 for parts, with labor costs adding another $80 to $150 per hour. Dealerships may charge higher rates, while independent shops may offer more competitive pricing. Always consider the make, model, and engine type, as these factors can influence the overall cost.

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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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