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P0878 2015 GMC Sierra Code - Transmission Fluid Pressure Switch 4 Circuit High Voltage

Quick Answer

The P0878 diagnostic trouble code (DTC) for a 2015 GMC Sierra indicates a problem with the Transmission Fluid Pressure Switch 4 Circuit High Voltage. Common causes include Faulty transmission fluid pressure switch, Wiring issues in the circuit, Malfunctioning transmission control module (TCM). 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
P0878 2015 GMC Sierra indicates Transmission Fluid Pressure Switch 4 Circuit High Voltage.
Common causes
Common causes include Faulty transmission fluid pressure switch, Wiring issues in the circuit, Malfunctioning transmission control module (TCM).
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 11, 2024
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Code P0878 2015 GMC Sierra Description

The P0878 diagnostic trouble code (DTC) for a 2015 GMC Sierra indicates a problem with the Transmission Fluid Pressure Switch 4 Circuit High Voltage. This code is specifically related to the transmission system of the vehicle. In automatic transmissions, the transmission fluid pressure switch plays a crucial role in monitoring and controlling the pressure of the transmission fluid. The switch signals the vehicle's computer system about the pressure levels in the transmission, allowing the system to make necessary adjustments for smooth gear shifting and overall transmission performance.

OBDII Code P0878 2015 GMC Sierra - Transmission Fluid Pressure Switch 4 Circuit High Voltage
P0878 2015 GMC Sierra Code - Transmission Fluid Pressure Switch 4 Circuit High Voltage

Common Causes of P0878 2015 GMC Sierra

  1. Faulty transmission fluid pressure switch
  2. Wiring issues in the circuit
  3. Malfunctioning transmission control module (TCM)
  4. Low transmission fluid levels
  5. Contaminated or degraded transmission fluid

Symptoms of P0878 2015 GMC Sierra

  1. Harsh shifting between gears
  2. Delayed engagement when shifting into gear
  3. Erratic gear changes or slipping
  4. Illumination of the Check Engine Light
  5. Reduced fuel efficiency

How to Fix P0878 2015 GMC Sierra

  1. Perform a diagnostic scan to confirm the P0878 code and identify the specific cause of the issue.
  2. Inspect the transmission fluid pressure switch and its wiring for any damage or corrosion. Replace if necessary.
  3. Check the transmission fluid level and condition. Top up or replace the fluid as needed.
  4. Test the transmission system to ensure proper pressure readings and smooth gear shifting.
  5. Clear the DTC and test drive the vehicle to verify that the issue has been resolved.

Cost to Fix P0878 2015 GMC Sierra

The cost of repairing a Transmission Fluid Pressure Switch 4 Circuit High Voltage issue can vary depending on the specific cause of the problem and the extent of the repairs needed. Generally, the cost of parts for this repair could range from $50 to $200, while labor costs could range from $100 to $300. Overall, the total repair cost could be anywhere from $150 to $500. However, it's essential to note that these are rough estimates, and actual costs may vary based on factors such as location, vehicle make and model, and the specific shop rates. It's recommended to obtain quotes from reputable auto repair shops to get a more accurate cost estimate for this 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.

Frequently Asked Questions about P0878 2015 GMC Sierra Code

1. What are common symptoms of OBDII code P0878 in a 2015 GMC Sierra?

Common symptoms include harsh shifting, transmission slipping, decreased fuel efficiency, and an illuminated Check Engine light.

2. What can cause OBDII code P0878 in a 2015 GMC Sierra?

The most common cause of code P0878 is a faulty transmission fluid pressure switch 4, high voltage in the transmission control module.

3. How can I diagnose OBDII code P0878 in my 2015 GMC Sierra?

To diagnose code P0878, a mechanic will typically use a scan tool to retrieve the code, inspect the transmission fluid pressure switch 4 and its circuit for any damage or malfunction.

4. Can I continue driving my 2015 GMC Sierra with OBDII code P0878?

It is not recommended to continue driving with code P0878 as it can lead to further damage to the transmission. It is best to address the issue promptly to avoid costly repairs.

5. How can I repair OBDII code P0878 in my 2015 GMC Sierra?

Repairing code P0878 usually involves replacing the faulty transmission fluid pressure switch 4 and clearing the code from the vehicle's memory using a scan tool.

6. Are there any DIY tips for fixing OBDII code P0878 in a 2015 GMC Sierra?

While it's recommended to have a professional diagnose and repair code P0878, DIYers with experience in automotive repairs can attempt to replace the transmission fluid pressure switch 4 themselves.

7. Will resetting the Check Engine light resolve OBDII code P0878 in my 2015 GMC Sierra?

Simply resetting the Check Engine light will not fix code P0878. The underlying issue causing the high voltage in the transmission fluid pressure switch 4 circuit needs to be addressed.

8. How much does it cost to repair OBDII code P0878 in a 2015 GMC Sierra?

The cost of repairing code P0878 can vary depending on the labor rates and parts pricing in your area. On average, the repair can range from $200 to $500.

9. Can bad transmission fluid cause OBDII code P0878 in a 2015 GMC Sierra?

While bad transmission fluid can affect the overall health of the transmission, it is not a common cause of code P0878. The issue is typically related to the transmission fluid pressure switch 4 circuit.

10. How long does it take to repair OBDII code P0878 in a 2015 GMC Sierra?

The repair time for code P0878 can vary depending on the mechanic's experience and workload. On average, the repair can take anywhere from 1 to 3 hours to complete.

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