P27AC 2018 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 2018 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.
Code P27AC 2018 GMC Sierra Description
What are the Possible Causes of the DTC P27AC 2018 GMC Sierra?
- Solenoid Valve Characterization Reprogramming
How to Fix the DTC P27AC 2018 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 2018 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.
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Frequently Asked Questions about P27AC 2018 GMC Sierra Code
1. What does the OBDII code P27AC mean on a 2018 GMC Sierra?
P27AC indicates that the Transmission Control Module (TCM) has detected an issue with the calibration of Solenoid Valve 6 in the transmission.
2. What are the common symptoms of code P27AC in a 2018 GMC Sierra?
Symptoms may include erratic shifting, harsh or delayed gear changes, transmission slipping, or the Check Engine Light being illuminated.
3. What causes the P27AC code to appear?
Common causes include a faulty transmission solenoid, incorrect software calibration in the TCM, wiring or connection issues, or debris in the transmission fluid.
4. Can I drive my 2018 GMC Sierra with a P27AC code?
Driving with this code is not recommended as it can cause further damage to the transmission or lead to unsafe driving conditions due to shifting issues.
5. How is the P27AC code diagnosed?
A technician will use a scan tool to verify the code, inspect the transmission wiring and connectors, check the solenoid's operation, and ensure the TCM software is up-to-date.
6. What repairs are commonly needed to fix the P27AC code?
Repairs may include replacing the faulty solenoid, updating the TCM software, repairing damaged wiring, or performing a transmission fluid flush.
7. How much does it cost to repair a P27AC code on a 2018 GMC Sierra?
Repair costs vary but typically range from $200 to $500 for solenoid replacement and up to $150 for a TCM software update.
8. Can low transmission fluid cause the P27AC code?
Yes, low or contaminated transmission fluid can affect solenoid operation and may trigger the P27AC code.
9. Does the P27AC code require reprogramming the TCM?
In some cases, reprogramming or updating the TCM software may resolve the issue if the problem is calibration-related.
10. How can I prevent the P27AC code from recurring?
Regularly maintain your transmission by checking fluid levels, using the correct fluid type, and having the TCM software updated as needed.
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