P27A9 2018 GMC Sierra Code - Transmission Control Solenoid Valve 3 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
- P27A9 2018 GMC Sierra indicates Transmission Control Solenoid Valve 3 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 P27A9 2018 GMC Sierra Description
What are the Possible Causes of the DTC P27A9 2018 GMC Sierra?
- Solenoid Valve Characterization Reprogramming
How to Fix the DTC P27A9 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 P27A9 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 P27A9 2018 GMC Sierra Code
1. What does the OBDII code P27A9 mean on a 2018 GMC Sierra?
The code P27A9 indicates that the Transmission Control Module (TCM) has detected an issue with the calibration of Transmission Control Solenoid Valve 3.
2. What are the common symptoms of code P27A9 in a 2018 GMC Sierra?
Symptoms may include harsh or delayed shifting, transmission slipping, poor acceleration, or the illumination of the check engine light.
3. What causes the P27A9 code to appear?
Common causes include a faulty solenoid valve, incorrect TCM programming, low transmission fluid levels, or wiring and connector issues in the transmission control circuit.
4. Can I drive my 2018 GMC Sierra with the P27A9 code?
While the vehicle may still be drivable, driving with this code can cause further damage to the transmission. It’s best to address the issue promptly.
5. How is the P27A9 code diagnosed?
A technician will typically use a scan tool to confirm the code, inspect the transmission wiring and connectors, check fluid levels, and test the solenoid valve and TCM for proper operation.
6. What is the most common repair for the P27A9 code?
The most common repair is replacing the faulty solenoid valve or updating the TCM software to correct calibration issues.
7. Can low transmission fluid cause the P27A9 code?
Yes, low or dirty transmission fluid can affect solenoid performance and lead to this code. Checking and replenishing the fluid is a good first step.
8. How much does it cost to fix the P27A9 code on a 2018 GMC Sierra?
Repairs can cost between $150 and $1,000 depending on whether the issue is a simple fluid change, solenoid replacement, or TCM reprogramming.
9. Is it necessary to reprogram the TCM for the P27A9 code?
Reprogramming may be required if the issue stems from incorrect calibration data in the TCM. A dealership or qualified technician can perform this update.
10. Can I clear the P27A9 code without fixing the problem?
Clearing the code without addressing the root cause will likely result in the code returning and could lead to further transmission issues over time.
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