P0743 on 2012-2014 Kia Soul: Torque Converter Solenoid Fixes

What's Unique About the 2012-2014 Kia SOUL

For this era of Kia vehicles, including the Soul with the 6-speed A6GF1 or A6MF1 automatic transmission, failure of the transmission solenoids is a well-documented issue. Kia issued Technical Service Bulletin #TSBTRA051R1 which specifically addresses this code, advising technicians to replace the individual solenoids rather than the entire, much more expensive, transmission assembly. This makes the diagnosis more straightforward than on other vehicles where the cause might be less clear.

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 start of the second generation (2014). However, both generations used a variant of the Hyundai/Kia 6-speed automatic transmission (A6GF1/A6MF1), and this issue is common to the transmission itself, so the causes and fixes are consistent across these model years.

Symptoms You May Notice

• Check Engine Light is on
• Poor fuel economy
• Engine RPMs are higher than usual at highway speeds
• Vehicle may stall when coming to a stop
• Transmission may shift harshly or feel like it's shuddering
• In some cases, the transmission may enter a "limp mode," often stuck in 3rd gear

Most Likely Causes

1. Failed Torque Converter Clutch (TCC) Solenoid 🔴 High Probability → Shop Automatic Transmission Torque Converter This is a known failure point on Kia's 6-speed automatic transmissions, as acknowledged by TSB #TSBTRA051R1. The solenoids are subject to electrical failure over time.
   How to confirm: After confirming the wiring is intact, a technician can test the solenoid's internal resistance with a multimeter. 🎬 Watch: How to test solenoid resistance on Kia transmissions For the A6GF1/A6MF1 transmission, the TCC (a linear solenoid) should measure approximately 5.1 ohms. A reading of infinite resistance (open) or near-zero (short) indicates failure. A scan tool can also command the solenoid on/off to check for a response.
   Typical fix: Replace the faulty solenoid. This part is located inside the transmission on the valve body.
   Est. part cost: $50-$150
2. Wiring Harness or Connector Issue 🟡 Medium Probability The main transmission harness connector is exposed and can suffer from internal corrosion. Additionally, the internal transmission harness is a known weak point where solder joints can crack over time. A separate TSB (SA499) was also issued for some Kia models for an external harness that could chafe against a bracket bolt, causing a short.
   How to confirm: Visually inspect the main electrical connector going to the transmission for corrosion, bent pins, or loose connections. Also inspect the harness routing near brackets for any signs of chafing. Perform a continuity test on the wires from the TCM to the solenoid connector. If external wiring is good, the valve body must be removed to inspect the internal harness for cracked solder joints.
   Typical fix: Clean corroded connector pins or replace the affected section of the wiring harness. If chafing is found, repair the wires and re-route or protect the harness. If internal solder joints are cracked, replace the internal transmission wire harness. 🎬 See how to diagnose harness open circuit issues
   Est. part cost: $0-$300
3. Low or Dirty Transmission Fluid ⚪ Low Probability → Shop Transmission Assembly While not a direct cause of an electrical code, old, contaminated fluid can cause solenoids to stick, overheat, and eventually fail electrically. These transmissions are specified to use SP-IV fluid.
   How to confirm: Check the transmission fluid level and condition. This must be done via a fill plug on the side of the transmission, as there is no dipstick. If the fluid is dark, burnt-smelling, or contains debris, it is overdue for service.
   Typical fix: Perform a transmission fluid and filter change using SP-IV fluid. This is often done as part of the solenoid replacement.
   Est. part cost: $70-$150

Rare But Worth Checking

• Faulty Powertrain Control Module (PCM): → Shop Engine Control Module (ECM) This is very rare. The PCM should only be considered after all other possibilities, including the solenoid and all wiring, have been exhaustively tested and ruled out.

Diagnosis Steps

1. Check the transmission fluid level and condition. Ensure it is full, clean, and of the correct SP-IV type.
2. Use an OBD-II scanner to check for any other transmission-related codes, especially other solenoid faults like P0748, P0753, etc.
3. Inspect the main transmission wiring harness and connector for any signs of corrosion, damage, or loose connections. Pay special attention to where the harness may contact brackets.
4. Using a wiring diagram, test for power at the TCC solenoid supply pin in the main transmission connector. It should have battery voltage (~12.6V key on, ~14V engine running).
5. Using a multimeter, measure the resistance of the TCC solenoid. It should be approximately 5.1 ohms for this transmission. An open circuit (infinite resistance) or short (near-zero resistance) indicates a failed solenoid.
6. If the wiring and solenoid resistance check out, the fault may be intermittent (e.g., a cracked internal harness solder joint) or, in rare cases, within the PCM.

Parts You'll Likely Need

• Automatic Transmission Control Solenoid (TCC) (OEM #46313-3B770) — This is the most common failure part for code P0743 on this vehicle, as supported by the manufacturer's TSB. It is also referred to as the '2-6 Brake and Torque Converter Clutch' solenoid.
  Trusted brands: Kia (OEM), Hyundai (OEM), Rostra
  OEM price range: $70-$120
  Aftermarket price range: $40-$80
• Automatic Transmission Fluid (OEM #Kia SP-IV) — Fluid must be replaced when the transmission pan is removed for solenoid replacement. About 4-5 quarts are needed for a pan drop.
  Trusted brands: Kia (OEM), Idemitsu, Valvoline
  OEM price range: $15-$25/quart
  Aftermarket price range: $8-$15/quart
• Automatic Transmission Pan Gasket — A new gasket is required to prevent leaks after reinstalling the transmission pan. Some pans use RTV sealant instead of a pre-made gasket.
  Trusted brands: Kia (OEM), Fel-Pro, Mahle
  OEM price range: $20-$40
  Aftermarket price range: $10-$25

Related Codes That Often Appear With This One

• P0741 — P0741 indicates 'TCC Circuit Performance or Stuck Off.' It can appear alongside P0743 if the electrical fault is causing a performance issue. Both codes are often mentioned in the same TSBs.
• P0748, P0753, P0758, etc. — These are electrical fault codes for other transmission solenoids. TSB TSBTRA051R1 groups all these codes together, as a failure of one solenoid suggests others may be weak, or there may be a shared wiring harness problem.

Technical Service Bulletins (TSBs) & Recalls

• TSBTRA051R1: Provides information for replacing various shift solenoids on 6-speed automatic transaxles for multiple DTCs including P0743, and advises against replacing the entire transaxle.
• SA499: A service action for some Kia models to upgrade the transmission wire harness to prevent it from chafing and shorting out on nearby components.

Platform-Specific Known Issues

• A known issue documented in Kia Technical Service Bulletin #TSBTRA051R1 points to solenoid failure as the root cause for P0743 and other related codes, advising against full transmission replacement.
• Some Kia models have been subject to Service Action SA499, which involves upgrading/protecting the transmission wire harness to prevent chafing on a bracket bolt that could lead to electrical shorts and codes like P0743.

Mechanic-Grade Diagnostic Values

• TCC Solenoid (Linear VFS) Resistance — expected: 5.1 Ω. Failure: A reading of infinite (open) or near-zero (short) resistance.
• On/Off Shift Solenoid (SSA/SSB) Resistance — expected: 10-11 Ω. Failure: Out of spec reading. This value helps differentiate between solenoid types during valve body testing.
• Solenoid Supply Voltage at Transmission Connector — expected: ~12.6V (Key On, Engine Off) or ~14V (Engine Running). Failure: Significantly lower voltage points to a wiring issue between the TCM and the transmission.

Scan Tool Commands That Help

• Kia GDS (Global Diagnostic System): TCC Solenoid Activation Test / Actuation Test — To manually command the TCC solenoid on and off. This helps verify if the solenoid is mechanically functioning (audible click) and if the control circuit from the TCM is working correctly.
• Kia GDS (Global Diagnostic System): Resetting Auto Trans Adaptive Values — This should be performed after replacing the valve body or any solenoids to clear the TCM's learned shift patterns, allowing it to adapt to the new components for smooth operation.
• Kia GDS / KDS: ECU Upgrade / Vehicle S/W Management — To check for and install any available software updates for the Transmission Control Module (TCM). An update can sometimes fix logic errors that may cause false diagnostic codes.

Wiring & Ground Locations

• Transmission Control Module (TCM) — In the engine bay, located under the air cleaner assembly and the battery tray.. This is the control unit that sends the signal to the TCC solenoid. All wiring tests for the solenoid circuit originate or terminate here.
• Main Transmission Harness Connector — The large, round electrical connector on the exterior of the transmission case, below the battery area.. This is a common point of failure due to corrosion or poor pin fitment. Pin 10 is the power supply for the TCC solenoid and is a known pin to lose continuity.
• Internal Transmission Wire Harness — Inside the transmission, attached to the valve body.. The solder joints on this internal harness are a known weak point and can develop micro-cracks, leading to intermittent open circuits for the solenoids, including the TCC solenoid which triggers P0743.

Real Owner Repair Stories

• YouTube video on Kia Spectra Transmission Codes (2008 Kia Spectra (similar transmission architecture)) — P0743, P0700, P0711; harsh clunking, failure to upshift or downshift.
  ❌ Tried (didn't work) The owner directly targeted the known common failure point.
  ✅ What actually fixed it The internal transmission wire harness was removed and the cracked solder joints were repaired. The user noted this is a very common failure point for these transmissions.

Model Year Variations Within This Range

• 2012-2014: The specific 6-speed automatic transmission model depends on the engine. Souls with the 1.6L engine are equipped with the A6GF1 transmission, while Souls with the 2.0L engine use the more robust A6MF1 transmission. The TSB and solenoid failure issue applies to both.