P0758 on 2012-2014 Kia Soul: Shift Solenoid 'B' Electrical Fault Causes and Fixes

What's Unique About the 2012-2014 Kia SOUL

The 2012-2014 Kia Soul, along with many other Kia and Hyundai models, uses the A6GF1 6-speed automatic transmission. This transmission family has a widely documented history of shift solenoid failures. The issue is so common that Kia issued a specific Technical Service Bulletin (TSB #TSBTRA051R1) advising technicians to replace the individual solenoids rather than the much more expensive transaxle assembly. This is a critical piece of information for owners, as it points directly to a cost-effective and targeted repair confirmed by numerous owner experiences across shared platforms.

Diagnostic Flowchart

Tap your situation to follow the diagnostic path that matches what you're seeing on this vehicle.

Generation note: The 2012-2014 range covers the end of the first generation (2012-2013) and the beginning of the second generation (2014) Kia Soul. Both generations in this period could be equipped with the 6-speed A6GF1 automatic transmission, and the TSB and associated solenoid issues apply to vehicles with this transmission.

Symptoms You May Notice

• Check Engine Light is on
• Transmission gets stuck in one gear (typically 3rd gear, known as 'limp mode').
• Harsh, jerky, or delayed shifting, sometimes described as a 'slip-bump' or 'flare-up' between gears.
• Failure to shift into or out of certain gears, particularly 2nd and 3rd.
• Sluggish acceleration from a stop.
• Decreased fuel efficiency.

Most Likely Causes

1. Failed Shift Solenoid 'B' 🔴 High Probability This is a well-documented failure point on Kia's 6-speed automatic transmissions, as confirmed by TSB #TSBTRA051R1. The solenoid's internal coil can burn out or develop an open/short circuit from heat and age.
   How to confirm: After accessing the solenoid on the valve body, a technician can test its internal resistance with a multimeter. A reading outside 🎬 See how to clean and test your 6-speed transmission solenoids. the manufacturer's specification confirms failure. For this specific VFS solenoid (2-6 Brake), the expected resistance is approximately 5.1 to 5.3 ohms.
   Typical fix: Replace the faulty Shift Solenoid 'B'. The TSB explicitly advises replacing the solenoid, not the entire transmission.
   Est. part cost: $60-$120
2. Internal Wiring Harness Issue 🟡 Medium Probability The wiring harness is located inside the transmission pan, constantly exposed to hot transmission fluid. Over time, the insulation can become brittle, leading to chafing, shorts, or open circuits at the connector pins. TSBs from Hyundai for the same transmission often recommend replacing the harness along with the solenoid.
   How to confirm: Visually inspect the harness for signs of damage, chafing, or brittle wires once the transmission pan is removed. A continuity test can be performed from the solenoid connector to the main transmission connector to check for open circuits or shorts.
   Typical fix: Replace the internal transmission wiring harness (Part No. 46307-3B650). This is often done as a preventative measure when replacing the solenoid.
   Est. part cost: $80-$150
3. Low or Contaminated Transmission Fluid ⚪ Low Probability
   How to confirm: Check the transmission fluid level and condition. The fluid should be at the correct level, red in color, and not smell burnt. Dark, burnt, or sludgy fluid indicates a problem that can contribute to solenoid failure.
   Typical fix: Perform a transmission fluid and filter change using fluid that meets Kia's SP-IV specification. However, this is unlikely to fix an existing electrical code but is critical preventative maintenance and necessary as part of the solenoid replacement job.
   Est. part cost: $70-$150

Rare But Worth Checking

• Faulty Transmission Control Module (TCM): While rare, the driver circuit within the TCM that controls the solenoid can fail. This should only be considered after the solenoid and wiring have been tested and confirmed to be good. In some cases, multiple solenoid codes (e.g., P0758 and P0763) appearing together can point towards a failing TCM.

Diagnosis Steps

1. Scan the vehicle's computer for P0758 and any other stored codes. Note the freeze-frame data.
2. Check the transmission fluid level and condition. Ensure it is clean, red, and at the proper level per the manufacturer's procedure (often at a specific temperature).
3. Inspect the external transmission wiring harness and connectors for any visible damage, corrosion, or loose connections.
4. If possible, use a professional scan tool to command Shift Solenoid 'B' on and off to check its response and monitor live data from the TCM.
5. Drain the transmission fluid and remove the transmission oil pan to access the internal components.
6. Visually inspect the internal wiring harness for any signs of damage, degradation, or burnt connector pins.
7. Locate Shift Solenoid 'B' (the 2-6 Brake Solenoid) on the valve body. It is a Variable Force Solenoid (VFS).
8. Disconnect the solenoid and test its resistance with a multimeter. Compare the reading to the manufacturer's specification, which should be around 5.1-5.3 ohms. An open (infinite ohms) or shorted (zero ohms) reading indicates failure.
9. If the solenoid resistance is out of spec, replace it. If the solenoid tests good, perform a continuity test on the wiring harness. If the harness is also good, the problem may be in the TCM.

Parts You'll Likely Need

• Automatic Transmission Control Solenoid (Shift Solenoid 'B') (OEM #46313-2F000) — This is the most common failure part for code P0758 on this vehicle, as identified by Kia's own service bulletin and extensive owner accounts. It is also referred to as the 2-6 Brake Solenoid. Note that part numbers can be superseded; related numbers include 46313-2F100, 46313-2F200, and 46313-2F400.
  Trusted brands: Kia (OEM), Hyundai (OEM), Rostra
  OEM price range: $80-$120
  Aftermarket price range: $50-$90
• Automatic Transmission Internal Wire Harness (OEM #46307-3B650) — The internal harness is a frequent secondary failure point due to heat and fluid exposure. It is often replaced preventatively along with the solenoid, and is recommended by some related TSBs. This part number may supersede older versions like 46307-3B620.
  Trusted brands: Kia (OEM), Hyundai (OEM)
  OEM price range: $100-$150
  Aftermarket price range: $70-$110
• Automatic Transmission Fluid (SP-IV) — The fluid must be drained to access the solenoid and should be replaced with new fluid meeting Kia's SP-IV specification. Typically 4-5 quarts are needed for a pan drop.
  Trusted brands: Kia (OEM), Idemitsu, Valvoline, Eneos
  OEM price range: $15-$25 per quart
  Aftermarket price range: $8-$15 per quart
• Transmission Pan Gasket or RTV Sealant (OEM #45285-3B700 (Verify by VIN)) — A new gasket or sealant is required to prevent leaks when reinstalling the transmission pan. Some A6GF1 models use a reusable gasket, while others require RTV sealant.
  Trusted brands: Kia (OEM), Fel-Pro, Permatex
  OEM price range: $20-$40
  Aftermarket price range: $10-$25

Related Codes That Often Appear With This One

• P0700 — P0700 is a general code indicating the TCM has stored a fault. It acts as a 'heads-up' that a more specific transmission code, like P0758, is present.
• P0763 — This code is for an electrical fault in Shift Solenoid 'C'. If multiple solenoid codes appear together, it may point to a common problem like a faulty wiring harness or a failing TCM affecting multiple circuits. Both are listed in the same TSB.
• P0741 — This code for the Torque Converter Clutch Solenoid is also covered under TSB #TSBTRA051R1, indicating it's another common failure point within the same valve body assembly.

Technical Service Bulletins (TSBs) & Recalls

• TSBTRA051R1: Advises on the replacement of various shift solenoids (including for P0758, designated as 26-B) on 6-speed automatic transaxles and explicitly states not to replace the entire transaxle for this issue.
• Hyundai TSB 14-AT-003: A related bulletin for Hyundai vehicles with the same transmission family, providing similar diagnostic and repair procedures, including replacing the solenoid and internal harness for P0758.

Platform-Specific Known Issues

• A known issue with the 6-speed automatic transmission (A6GF1) involves the failure of individual shift solenoids, prompting Kia to issue TSB #TSBTRA051R1. The bulletin specifically instructs technicians to replace only the affected solenoid(s) and not the entire transaxle, saving significant cost.

Mechanic-Grade Diagnostic Values

• Shift Solenoid 'B' (2-6 Brake, VFS type) Coil Resistance — expected: 5.1 - 5.3 ohms. Failure: A reading of infinite ohms (open circuit), near zero ohms (short circuit), or a value significantly outside the expected range.
• On/Off Type Shift Solenoid (e.g., SSA) Coil Resistance — expected: 10 - 11 ohms. Failure: A reading outside this range. This is for the two on/off solenoids and helps differentiate them from the VFS types during testing.
• Voltage at Solenoid 'B' Connector — expected: ~12V (battery voltage) pulse when commanded ON by the TCM.. Failure: No voltage when commanded, or constant voltage when not commanded, points to a wiring or TCM driver issue.

Scan Tool Commands That Help

• Kia GDS (Global Diagnostic System): Actuation Test / Active Test — This is a critical bidirectional function used after checking for codes. It allows a technician to command Shift Solenoid 'B' to turn on and off directly from the scan tool. Listening for an audible 'click' from the transmission pan can quickly confirm if the solenoid is mechanically responding to the electrical command. This helps isolate the fault between the TCM, wiring, and the solenoid itself.
• Kia GDS (Global Diagnostic System): Resetting Adaptive Values — After replacing a solenoid or the valve body, this function should be used to clear the transmission's learned shift adaptations. This ensures the TCM relearns shift points with the new components, preventing harsh or erratic shifting after the repair.

Wiring & Ground Locations

• Solenoid Valve Connector — On the exterior of the automatic transaxle case. This is the main connector where the internal wiring harness passes through the case to connect to the main vehicle harness.. This is the primary external test point for checking continuity and voltage between the TCM and the internal solenoids without dropping the transmission pan. Corrosion or damage here can cause P0758.
• Chassis Ground Bolt — Often found near the interior fuse panel, behind the driver's side kick panel. It is typically a 10mm or 12mm bolt with multiple ground wires attached to it.. A poor ground for the TCM can cause a variety of electrical faults, including erroneous solenoid codes. While not the most likely cause, verifying the TCM has a clean ground is a fundamental step in diagnosing complex electrical issues.
• Primary Engine/Transmission Ground — A heavy gauge cable connecting the battery's negative terminal to the engine block or the transmission case itself.. The entire transmission electrical system relies on this main ground path. Corrosion or a loose connection here can cause widespread issues, including solenoid circuit faults.

Real Owner Repair Stories

• YouTube Channel 'TCU/ECU Repair Guide' (Kia Forte (year not specified, but confirmed to have the A6GF1 transmission)) — Harsh shifting, jerking, and fault codes P0758 (Shift Solenoid B Electrical) and P0763 (Shift Solenoid C Electrical).
  ❌ Tried (didn't work) Solenoids were tested and confirmed to be working., Wiring between the TCM and the transmission was checked and found to be normal.
  ✅ What actually fixed it The root cause was an internal failure of the Transmission Control Module (TCM). Specifically, the two power driver ICs on the circuit board that control solenoids 'B' and 'C' had failed and were replaced on the board.

OEM Part Supersession History

• 46307-3B610, 46307-3B620 → 46307-3B650 — These are earlier versions of the internal transmission wiring harness. The newest part number, 46307-3B650, features revisions for improved durability against heat and fluid degradation.
  Heads up: The newer harness is a direct replacement for the older versions.
• N/A → N/A — Solenoid part numbers are frequently updated (e.g., 46313-2F000, 46313-2F100, 46313-2F200).
  Heads up: CRITICAL: The plastic connector color of the solenoids may change with new part numbers and should NOT be used for identification. Always verify the correct solenoid by its location on the valve body, not by color.