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Engine-Codes – GMC – P0990 2015 GMC Sierra

P0990 2015 GMC Sierra Code - Transmission Fluid Pressure Switch 5 Circuit High Voltage

Quick Answer

The P0990 diagnostic trouble code (DTC) for a 2015 GMC Sierra relates to the Transmission Fluid Pressure Switch 5 Circuit High Voltage. Common causes include Faulty transmission fluid pressure switch 5, Wiring issues or a short circuit in the transmission fluid pressure switch circuit, Low transmission fluid levels or contaminated fluid. 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
P0990 2015 GMC Sierra indicates Transmission Fluid Pressure Switch 5 Circuit High Voltage.
Common causes
Common causes include Faulty transmission fluid pressure switch 5, Wiring issues or a short circuit in the transmission fluid pressure switch circuit, Low transmission fluid levels or contaminated fluid.
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 Sep 17, 2024
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Code P0990 2015 GMC Sierra Description

The P0990 diagnostic trouble code (DTC) for a 2015 GMC Sierra relates to the Transmission Fluid Pressure Switch 5 Circuit High Voltage. This code indicates that there is a high voltage condition detected in the circuit that controls the transmission fluid pressure switch 5. The transmission fluid pressure switch is a crucial component in the vehicle's transmission system, responsible for monitoring and regulating the hydraulic pressure within the transmission. When the pressure switch detects a high voltage signal, it means that there is an issue with the transmission fluid pressure regulation, which can lead to various performance issues.

OBDII Code P0990 2015 GMC Sierra - Transmission Fluid Pressure Switch 5 Circuit High Voltage
P0990 2015 GMC Sierra Code - Transmission Fluid Pressure Switch 5 Circuit High Voltage

Common Causes of P0990 2015 GMC Sierra

  1. Faulty transmission fluid pressure switch 5
  2. Wiring issues or a short circuit in the transmission fluid pressure switch circuit
  3. Low transmission fluid levels or contaminated fluid
  4. Malfunctioning transmission control module (TCM)
  5. Electrical issues within the transmission system

Symptoms of P0990 2015 GMC Sierra

  1. Illumination of the check engine light on the dashboard
  2. Erratic shifting or harsh engagement when changing gears
  3. Transmission slipping or delayed response
  4. Decreased fuel efficiency
  5. Transmission overheating

How to Fix P0990 2015 GMC Sierra

  1. Begin by diagnosing the specific cause of the high voltage condition in the transmission fluid pressure switch 5 circuit using a diagnostic scanner.
  2. Inspect the wiring harness and connections related to the transmission fluid pressure switch for any signs of damage or corrosion.
  3. Test the transmission fluid pressure switch 5 for proper functionality and replace it if necessary.
  4. Check the transmission fluid level and condition, topping off or replacing it as needed.
  5. Clear the DTC and reset the vehicle's computer system to ensure the code does not reappear.

Cost to Fix P0990 2015 GMC Sierra

The typical repair costs for addressing the P0990 code on a 2015 GMC Sierra can range from $200 to $500, depending on the specific cause of the issue and the cost of parts and labor. It's important to note that diagnosis time and labor rates at auto repair shops can vary based on factors such as location, vehicle make and model, and engine type. Most auto repair shops charge between $80 and $150 per hour for labor, but rates may be higher in metropolitan areas or at dealerships, while independent shops may offer lower rates. For a more precise estimate, it is recommended to check with local auto repair shops.

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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.

Frequently Asked Questions about P0990 2015 GMC Sierra Code

1. What does the OBDII code P0990 mean on a 2015 GMC Sierra?

P0990 indicates a high voltage issue in the Transmission Fluid Pressure (TFP) Switch 5 Circuit, which monitors hydraulic pressure in the transmission for proper gear shifting.

2. What are the common symptoms of the P0990 code in a 2015 GMC Sierra?

Common symptoms include harsh or erratic shifting, the transmission stuck in a single gear, reduced engine performance, and an illuminated check engine light.

3. What causes the P0990 code to appear on a 2015 GMC Sierra?

Potential causes include a faulty TFP switch, damaged wiring or connectors in the TFP circuit, a malfunctioning transmission control module (TCM), or low or contaminated transmission fluid.

4. Can I drive my 2015 GMC Sierra with a P0990 code?

It is not recommended to drive with this code as it may cause further transmission damage or unsafe driving conditions due to erratic shifting.

5. How do I diagnose the P0990 code on a 2015 GMC Sierra?

Diagnosis involves checking the TFP switch and circuit for damage, testing the wiring for continuity, inspecting the transmission fluid level and condition, and scanning the TCM for additional codes.

6. How is the P0990 code repaired on a 2015 GMC Sierra?

Repairs may include replacing the TFP switch, repairing or replacing damaged wiring or connectors, flushing and refilling transmission fluid, or reprogramming or replacing the TCM.

7. How much does it cost to fix the P0990 code on a 2015 GMC Sierra?

Repair costs vary but can range from $150 to $500, depending on whether the switch, wiring, or TCM needs replacement and if professional labor is required.

8. Can low transmission fluid cause the P0990 code in a 2015 GMC Sierra?

Yes, low or contaminated transmission fluid can cause incorrect pressure readings, leading to the P0990 code.

9. Does the P0990 code mean the transmission is failing?

Not necessarily. While it could indicate a serious issue, it’s often related to a specific electrical or hydraulic problem that can be repaired without replacing the entire transmission.

10. Will clearing the P0990 code fix the issue on a 2015 GMC Sierra?

Clearing the code may temporarily turn off the check engine light, but the underlying issue must be addressed to prevent the code from returning.

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