AutoCodes – Generic – P099C

P099C Code - Shift Solenoid 'G' Control Circuit High

Quick Answer

The Transmission Control Module (TCM) monitors the Shift Solenoid signal. Common causes include Faulty Shift Solenoid 'G', Shift Solenoid 'G' harness is open or shorted, Shift Solenoid 'G' circuit poor electrical connection. 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: P099C indicates Shift Solenoid 'G' Control Circuit High.
Common causes: Common causes include Faulty Shift Solenoid 'G', Shift Solenoid 'G' harness is open or shorted, Shift Solenoid 'G' circuit poor electrical connection.
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.

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Code Popularity 12,864

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 May 11, 2019

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P099C Description

The Transmission Control Module (TCM) monitors the Shift Solenoid signal. The TCM sets the OBDII code when the Shift Solenoid is not to factory specifications.

OBDII Code P099C - Shift Solenoid 'G' Control Circuit High - AutoCodes.com — P099C Code - Shift Solenoid 'G' Control Circuit High

What does this mean?

What are the Possible Causes of the DTC P099C?

Faulty Shift Solenoid 'G'
Shift Solenoid 'G' harness is open or shorted
Shift Solenoid 'G' circuit poor electrical connection

How to Fix the DTC P099C?

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 P099C 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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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 P099C Code

1. What are the common symptoms of OBDII code P099C (Shift Solenoid 'G' Control Circuit High)?

The common symptoms include harsh shifting, delayed shifting, transmission slipping, and illumination of the Check Engine Light.

2. What are the possible causes of OBDII code P099C?

Possible causes of this code include a faulty shift solenoid 'G', a damaged wiring harness, poor electrical connections, or issues with the transmission control module.

3. How can I diagnose OBDII code P099C?

Diagnosis typically involves using a scan tool to retrieve the code, performing a visual inspection of the wiring and connectors, testing the shift solenoid 'G' for proper operation, and checking the transmission fluid level and condition.

4. Can I continue driving with OBDII code P099C present?

It is not recommended to continue driving with this code present, as it can lead to further damage to the transmission. Seek professional diagnosis and repair as soon as possible.

5. How is OBDII code P099C (Shift Solenoid 'G' Control Circuit High) repaired?

Repair may involve replacing the faulty shift solenoid 'G', repairing the wiring or connectors, or resetting the transmission control module. It is best to consult a qualified mechanic for proper repair.

6. Are there any DIY tips for troubleshooting OBDII code P099C?

While basic visual inspection and checking the transmission fluid can be done by DIY enthusiasts, diagnosing and repairing the underlying issues causing this code may require specialized tools and expertise, best left to professionals.

7. What happens if OBDII code P099C is ignored?

Ignoring this code can lead to transmission issues such as poor shifting performance, transmission failure, and potential safety hazards. Prompt attention is recommended.

8. Is it expensive to fix OBDII code P099C?

The cost of fixing this code can vary depending on the root cause of the issue, the extent of damage, and the labor rates in your area. It's advisable to get a few quotes from reputable repair shops.

9. Can a transmission flush resolve OBDII code P099C?

A transmission flush is unlikely to resolve this specific code, as it is typically related to a specific component like the shift solenoid 'G' or wiring issues. It's best to address the root cause directly.

10. How can I prevent OBDII code P099C from occurring again?

Regular maintenance of the transmission system, including checking fluid levels, addressing any leaks promptly, and following the manufacturer's recommended service intervals, can help prevent issues like this code from reoccurring.