AutoCodes – Generic – P099B

P099B Code - Shift Solenoid 'G' Control Circuit Low

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: P099B indicates Shift Solenoid 'G' Control Circuit Low.
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 8,237

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
Comments
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Code P099B 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 P099B - Shift Solenoid 'G' Control Circuit Low - AutoCodes.com — P099B Code - Shift Solenoid 'G' Control Circuit Low

What does this mean?

What are the Possible Causes of the DTC P099B?

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

How to Fix the DTC P099B?

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 P099B 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.