P0743 on 2011-2015 Kia Forte: Torque Converter Solenoid Guide

What's Unique About the 2011-2015 Kia FORTE

For this generation of Kia Forte with the A6MF1 6-speed automatic transmission, the failure of individual transmission solenoids and the internal wiring harness is a well-documented issue. Kia acknowledged this by releasing Technical Service Bulletin TSBTRA051R1, which specifically instructs dealers to replace the faulty solenoids rather than the entire transaxle assembly. This is a crucial distinction that can save owners a significant amount of money by avoiding an unnecessary and expensive transmission replacement. The issue is common across many Hyundai and Kia models that share this transmission.

Diagnostic Flowchart

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

Generation note: The 2011-2015 year range covers the end of the first generation (TD, 2011-2013) and the beginning of the second generation (YD, 2014-2015). Both generations in this period used a 6-speed automatic transmission (A6MF1) susceptible to this solenoid issue, and the provided TSB applies across these model years and other Kia/Hyundai platforms.

Symptoms You May Notice

• Check Engine Light is on
• Transmission enters 'limp mode' (stuck in 3rd gear).
• Reduced fuel economy, especially at highway speeds.
• Engine RPMs are higher than usual during highway cruising
• Shuddering or vibration when the vehicle is stopping or at low speeds.
• Harsh or delayed shifting.
• Transmission may slip or feel like it pops into neutral.

Most Likely Causes

1. Failed Torque Converter Clutch (TCC) Solenoid 🔴 High Probability → Shop Automatic Transmission Torque Converter This is a known issue for this platform, as confirmed by Kia's Technical Service Bulletin TSBTRA051R1, which advises replacing the solenoids for this specific code. These solenoids are part of a larger group within the A6MF1 transmission family that has a high failure rate.
   How to confirm: A technician will drop the transmission pan to access the solenoid pack. The faulty solenoid can be identified by testing its electrical resistance with a multimeter. The specification for this solenoid is approximately 3.5 ± 0.2 Ω at 20°C (68°F). A reading outside this range, or an open/short circuit, confirms failure. The solenoid 🎬 See how to clean and test your A6MF1 solenoids. should also 'click' when 12V is applied.
   Typical fix: Replace the faulty TCC solenoid. Per TSB TSBTRA051R1, it is often recommended to replace the entire solenoid pack/harness assembly as a preventative measure.
   Est. part cost: $60-$120 for a single solenoid, $200-$350 for a complete solenoid block/harness assembly.
2. Failed Internal Transmission Wiring Harness 🟡 Medium Probability → Shop Transmission Assembly The internal wiring harness for the A6-family of transmissions is a known failure point. The ribbon-style connector can develop open circuits or shorts, leading to solenoid codes like P0743, often accompanied by other solenoid codes.
   How to confirm: After accessing the valve body, visually inspect the harness for discoloration, melted connectors, or damage. A technician can perform a continuity test from the main transmission connector to each solenoid pin. A voltage drop test can also reveal a bad connection that only appears under load.
   Typical fix: Replace the internal transmission wiring harness. 🎬 Watch: Diagnosing harness open circuits and electrical faults. This part often comes with the solenoids as a complete assembly.
   Est. part cost: $150-$300
3. Low or Dirty Transmission Fluid ⚪ Low Probability → Shop Transmission Assembly
   How to confirm: Check the transmission fluid level and condition. The fluid should be at the correct level and appear clean and red. Dark, burnt-smelling fluid or fluid with metal particles indicates a more serious internal problem that may have caused the solenoid to fail.
   Typical fix: Perform a transmission fluid drain and fill, and replace the transmission filter. This is often done as part of the solenoid replacement.
   Est. part cost: $50-$120 for fluid and filter
4. Wiring or Connector Issue (External) ⚪ Low Probability
   How to confirm: Visually inspect the external wiring harness going to the transmission for any signs of damage, corrosion, or loose connections. Test for continuity and voltage at the main transmission connector.
   Typical fix: Repair or replace the damaged section of the wiring harness or clean the connectors.
   Est. part cost: $10-$200 depending on the extent of damage

Rare But Worth Checking

• Faulty Transmission Control Module (TCM): → Shop Transmission Assembly This should only be considered after the solenoid, fluid, and all wiring (internal and external) have been confirmed to be in good working order. A faulty TCM can mimic the symptoms of a bad solenoid by failing to send the correct voltage signal.

Diagnosis Steps

1. Scan the vehicle's computer for any other stored trouble codes. Note if other solenoid codes are present, which may point to a harness issue.
2. Check the transmission fluid level and condition. Ensure it is full and not burnt or contaminated.
3. Inspect the external transmission wiring harness and connectors for any visible damage, corrosion, or loose pins.
4. If fluid and wiring are okay, the next step is to gain access to the solenoids by removing the transmission oil pan.
5. Visually inspect the internal wiring harness for any signs of damage or burnt terminals at the solenoid connectors.
6. Test the resistance of the TCC solenoid with a multimeter. It should measure approximately 3.5 ± 0.2 Ω at 20°C (68°F). An out-of-spec reading indicates a failed solenoid.
7. If the solenoid tests good, check for power and ground at the solenoid's electrical connector while commanding it on with a scan tool to rule out a wiring issue between the TCM and the solenoid. A voltage drop under load can indicate a faulty harness.
8. If all other components check out, the issue may lie with the Transmission Control Module (TCM), though this is rare.

Parts You'll Likely Need

• Automatic Transmission Solenoid (OEM #46313-23010 (Verify by VIN)) — This is the most common failure point for code P0743 on this vehicle, as documented by Kia's own service bulletin. Note that part number 46313-23000 is for older, 4/5-speed transmissions and is not correct for this vehicle. It is often sold as part of a complete solenoid/harness block.
  Trusted brands: Genuine Kia / Hyundai, Rostra, Standard Motor Products
  OEM price range: $90-$140
  Aftermarket price range: $50-$90
• Automatic Transmission Internal Wire Harness (OEM #46307-3B650 (Verify by VIN, often part of a valve body assembly)) — A common failure point that can cause P0743 and other solenoid codes. Often replaced along with the solenoids.
  Trusted brands: Genuine Kia / Hyundai
  OEM price range: $150-$250
  Aftermarket price range: $100-$180
• Automatic Transmission Filter Kit — Should be replaced whenever the transmission pan is removed to service the solenoids.
  Trusted brands: ATP, WIX, Beck Arnley
  OEM price range: $40-$60
  Aftermarket price range: $25-$40

Related Codes That Often Appear With This One

• P0741 — Indicates a performance issue or the TCC being stuck off, which can be caused by the same failing solenoid or a related hydraulic blockage.
• P0748, P0753, P0758, P0763, P0768, P0773 — These are all codes for other transmission solenoids. Kia's TSB groups them together, suggesting a common failure pattern within the solenoid pack or, more likely, a fault in the shared internal wiring harness.

Technical Service Bulletins (TSBs) & Recalls

• TSBTRA051R1: Provides information for replacing various shift solenoids on 6-speed automatic

Platform-Specific Known Issues

• A high failure rate of individual solenoids in the A6MF1 6-speed automatic transmission prompted Kia to issue Technical Service Bulletin TSBTRA051R1. The bulletin covers a range of solenoid-related DTCs, including P0743, and recommends replacing the solenoids while the transaxle is still in the vehicle to save time and money.
• The internal transmission wire harness is also a very common point of failure on these models, sometimes causing multiple solenoid codes to appear at once. A technician on YouTube demonstrated how a break in the internal ribbon harness can cause an intermittent open circuit, triggering codes.

Mechanic-Grade Diagnostic Values

• TCC Solenoid (Variable Force Solenoid) Resistance — expected: 5.1 Ω. Failure: A reading that is significantly higher, lower, or shows an open/short circuit.
• On/Off Shift Solenoid (SSA/SSB) Resistance — expected: 10-11 Ω. Failure: A reading outside of this range. This is useful for comparison when testing the entire solenoid pack.
• Transmission Fluid Temperature Sensor Resistance — expected: Approximately 2.51k Ω at 68°F (20°C). Failure: A significantly different reading, which could cause incorrect shifting and TCC operation.
• Solenoid Supply Voltage at Connector — expected: Close to battery voltage (approx. 12.6V with key on, 13.5-14.5V with engine running). Failure: Low or no voltage indicates a problem with the external wiring or the TCM.

Scan Tool Commands That Help

• Kia GDS/KDS (or compatible advanced scanner like Autel): Resetting Auto T/A Values — This function must be performed after replacing the transmission, valve body, solenoids, or internal harness to clear the old learned shift parameters. Failure to do so can result in continued poor shifting even with new parts.
• Kia GDS/KDS (or compatible advanced scanner): Relearn Adaptive Values (Drive Cycle) — After resetting the adaptive values, a specific drive cycle is required to 'teach' the TCM the correct solenoid pressures for the new components. This involves accelerating gently from a stop with 10-20% throttle to allow shifts through all gears while ATF temperature is between 86°F and 203°F.

Wiring & Ground Locations

• Transmission Ground Cable — A ground cable is bolted directly to the top or side of the transaxle housing, connecting it to the chassis.. A corroded or loose transmission ground can cause a variety of electrical issues, including erratic solenoid behavior and incorrect sensor readings, potentially triggering a P0743 code.
• Main Transmission Harness Connector — The main 16-pin connector is located on the top or front of the transaxle case, where the external vehicle harness connects to the internal transmission components.. This is the primary point for testing voltage and continuity from the TCM to the TCC solenoid without opening the transmission. A damaged pin or corrosion here can cause an open or short in the circuit.

OEM Part Supersession History

• 46307-3B610, 46307-3B620 → 46307-3B650 — Updated design to improve durability and prevent common electrical failures in the internal transmission harness.
  Heads up: The updated harness may have an integrated temperature sensor, whereas older versions had a separate, disconnectable sensor. It is recommended to always update to the latest harness version when performing repairs.

Model Year Variations Within This Range

• 2011-2015: While the A6MF1 transmission is used throughout this period, there were running changes to the internal wiring harness and temperature sensor. Early models may have a separate temp sensor, while later versions integrate it into the harness. When replacing the harness, it is critical to use the updated part number (46307-3B650) which may require replacing the sensor as part of the assembly.