Engine-CodesGMC – P0816 2016 GMC Sierra

P0816 2016 GMC Sierra Code - Downshift Switch Circuit

Quick Answer

The P0816 diagnostic trouble code (DTC) for a 2016 GMC Sierra relates to the Downshift Switch Circuit. Common causes include Faulty downshift switch, Wiring or connector issues in the downshift switch circuit, Defective transmission control module (TCM) or engine control module (ECM). 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
P0816 2016 GMC Sierra indicates Downshift Switch Circuit.
Common causes
Common causes include Faulty downshift switch, Wiring or connector issues in the downshift switch circuit, Defective transmission control module (TCM) or engine control module (ECM).
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 13, 2024
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Code P0816 2016 GMC Sierra Description

The P0816 diagnostic trouble code (DTC) for a 2016 GMC Sierra relates to the Downshift Switch Circuit. This code indicates that there is a malfunction in the circuit responsible for controlling the downshifting process in the transmission. In automatic transmissions, downshifting is essential for proper gear engagement and smooth operation of the vehicle. When this circuit malfunctions, it can lead to issues with shifting gears, which can affect the vehicle's performance, fuel efficiency, and overall drivability.

OBDII Code P0816 2016 GMC Sierra - Downshift Switch Circuit
P0816 2016 GMC Sierra Code - Downshift Switch Circuit

Common Causes of P0816 2016 GMC Sierra

  1. Faulty downshift switch
  2. Wiring or connector issues in the downshift switch circuit
  3. Defective transmission control module (TCM) or engine control module (ECM)
  4. Low transmission fluid level or contaminated fluid
  5. Electrical issues such as blown fuses or relays

Symptoms of P0816 2016 GMC Sierra

  1. Check engine light illuminated on the dashboard
  2. Harsh or delayed shifting between gears
  3. Transmission slipping or jerking during acceleration
  4. Inability to downshift when needed
  5. Reduced fuel efficiency

How to Fix P0816 2016 GMC Sierra

  1. Begin by using a diagnostic scanner to retrieve the trouble codes stored in the vehicle's computer system.
  2. Inspect the downshift switch and its circuit for any visible damage, corrosion, or loose connections.
  3. Test the downshift switch for proper functionality using a multimeter to check for continuity.
  4. Check the transmission fluid level and condition, topping off or replacing as needed.
  5. If the issue persists, consult a professional mechanic for further diagnosis and potential replacement of the TCM or ECM.

Cost to Fix P0816 2016 GMC Sierra

The cost of repairing a P0816 code on a 2016 GMC Sierra can vary depending on the specific cause of the issue. In general, the parts required for this repair, such as a new downshift switch or TCM, can range from $100 to $500. Labor costs at an auto repair shop typically range from $80 to $150 per hour. The total cost of the repair, including parts and labor, could range from $200 to $800 or more. It is advisable to consult with a trusted mechanic to get an accurate estimate based on the specific circumstances of your vehicle.

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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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