AutoCodes – GMC – P27AC 2017 GMC Sierra

P27AC 2017 GMC Sierra Code - Transmission Control Solenoid Valve 6 Calibration Incorrect

Quick Answer

The Transmission Control Solenoid Valve 1, 2, 3, 4, 5, 6, 7 have a unique current versus oil pressure characteristic that is used to properly upshift or downshift the transmission. Common causes include Solenoid Valve Characterization Reprogramming. 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: P27AC 2017 GMC Sierra indicates Transmission Control Solenoid Valve 6 Calibration Incorrect.
Common causes: Common causes include Solenoid Valve Characterization Reprogramming.
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.

Save to My Repairs My Repairs

AI answers can be wrong. Verify repairs with testing. Open full chat

Code Popularity 413

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Sep 22, 2022

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
Add Comment

💬 Need more help? Ask Coddy for instant answers — it's free!

Code P27AC 2017 GMC Sierra Description

The Transmission Control Solenoid Valve 1, 2, 3, 4, 5, 6, 7 have a unique current versus oil pressure characteristic that is used to properly upshift or downshift the transmission. The data for each solenoid valve is programmed into the Transmission Control Module (TCM). The Diagnostic Trouble Code (DTC) will be set when the Transmission Control Solenoid Valve Calibration Data has not been programmed.

OBDII Code P27AC 2017 GMC Sierra - Transmission Control Solenoid Valve 6 Calibration Incorrect - AutoCodes.com — P27AC 2017 GMC Sierra Code - Transmission Control Solenoid Valve 6 Calibration Incorrect

What does this mean?

What are the Possible Causes of the DTC P27AC 2017 GMC Sierra?

Solenoid Valve Characterization Reprogramming

How to Fix the DTC P27AC 2017 GMC Sierra?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P27AC 2017 GMC Sierra code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

Need more information about the P27AC 2017 GMC Sierra code?

Need more information on how to fix the P27AC 2017 GMC Sierra code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P27AC 2017 GMC Sierra code diagnosed by a professional: Find a repair shop in your area

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 P27AC 2017 GMC Sierra Code

1. What does the OBDII code P27AC mean on a 2017 GMC Sierra?

The code P27AC indicates that the Transmission Control Solenoid Valve 6 has an incorrect calibration, which affects the transmission's ability to shift properly.

2. What are the common symptoms of code P27AC in a 2017 GMC Sierra?

Symptoms may include rough or delayed shifting, transmission slipping, reduced fuel efficiency, and an illuminated check engine light.

3. What causes the P27AC code to appear?

Possible causes include a faulty solenoid valve, transmission fluid issues (low or dirty), damaged wiring or connectors, or a software calibration error in the transmission control module (TCM).

4. Can I still drive my 2017 GMC Sierra with a P27AC code?

Itâ€™s possible to drive temporarily, but continued operation may cause transmission damage or worsen existing issues. Itâ€™s best to address the problem promptly.

5. How is the P27AC code diagnosed?

A mechanic will use a scan tool to check for stored codes, inspect the solenoid valve and related wiring, test the transmission fluid, and verify the TCM calibration.

6. How do you fix the P27AC code on a 2017 GMC Sierra?

Repairs may involve replacing the faulty solenoid valve, updating the TCM software, repairing damaged wiring, or performing a transmission fluid flush.

7. How much does it cost to fix the P27AC code?

The repair cost can range from $200 to $1,000 depending on whether the solenoid needs replacement, software reprogramming, or a fluid service.

8. Can low transmission fluid cause the P27AC code?

Yes, low or contaminated transmission fluid can affect solenoid operation, potentially triggering the P27AC code.

9. Does the P27AC code require a TCM reprogramming?

In some cases, a TCM software update or reprogramming may resolve the calibration issue causing the P27AC code.

10. Can I fix the P27AC code myself?

If you have the tools and experience, you can check the fluid level, inspect wiring, or replace the solenoid. However, TCM updates and advanced diagnostics typically require professional equipment.