P0743 on 2012-2015 Kia Rio: Torque Converter Solenoid Causes and Fixes

What's Unique About the 2012-2015 Kia RIO

The 2012-2015 Kia Rio uses the A6GF1 6-speed automatic transmission, part of a family of transmissions where solenoid failure is a recognized issue. Kia issued a Technical Service Bulletin (TSB) #TSBTRA051R1 that specifically addresses this code, advising technicians to replace the individual solenoid 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 certain.

Diagnostic Flowchart

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

Symptoms You May Notice

• Check Engine Light is on
• Poor fuel economy
• Engine RPM is higher than usual at highway speeds
• Harsh or erratic shifting
• Transmission may feel like it's slipping
• Vehicle may enter 'limp mode', often getting stuck in 3rd gear. Some owners report it will shift up to 4th, then immediately jump back to 3rd and stay there.
• Engine may shudder or stall when coming to a stop.

Most Likely Causes

1. Failed Torque Converter Clutch (TCC) Solenoid 🔴 High Probability → Shop Automatic Transmission Torque Converter This is a known failure point on this platform's A6GF1 6-speed automatic transmission, as acknowledged by Kia's Technical Service Bulletin #TSBTRA051R1.
   How to confirm: A mechanic can use a professional scan tool to command the TCC solenoid on and off to check its response. The solenoid's internal resistance can also be tested with a multimeter after it's accessed. A user on Reddit reported success by testing the solenoids; the book value was 3.5 +/- 0.2 ohms, and their faulty TCC solenoid measured 3.0 ohms, confirming the failure.
   Typical fix: Replace the faulty TCC solenoid, which is located on the transmission's valve body.
   Est. part cost: $60-$150
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 wires can become brittle and break or short out over time due to heat and constant exposure to transmission fluid.
   How to confirm: After removing the transmission pan, visually inspect the harness for any signs of cracking, burnt plastic, or broken wires. Check for continuity from the solenoid connector back to the main transmission case connector plug.
   Typical fix: Replace the internal transmission wiring harness. This is often done at the same time as a solenoid replacement.
   Est. part cost: $70-$150
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, pinkish-red, and not smell burnt or contain debris. Note: This model does not have a traditional dipstick. The level must be checked via a fill plug on the side of the transmission case while the vehicle is running and at operating temperature.
   Typical fix: Perform a transmission fluid drain-and-fill using the correct Kia SP-IV specification fluid. If the fluid is very dirty or burnt, it may indicate more severe internal problems.
   Est. part cost: $50-$120
4. Damaged External Wiring or Connectors ⚪ Low Probability
   How to confirm: Visually inspect the external wiring harness leading to the transmission for any signs of damage, corrosion, or loose connections.
   Typical fix: Repair the damaged section of wiring or replace the faulty connector.
   Est. part cost: $20-$200

Rare But Worth Checking

• Faulty Transmission Control Module (TCM) or Powertrain Control Module (PCM): → Shop Engine Control Module (ECM) This is very rare and should only be considered after all other possibilities (solenoid, fluid, wiring) have been definitively ruled out. A replacement PCM for a 2013 Kia Rio can be very expensive, with parts alone costing over $1,500.

Diagnosis Steps

1. Scan the vehicle for any other transmission-related trouble codes to see if other solenoids are also reporting faults.
2. Check the transmission fluid level and condition. Ensure it is clean, at the proper level, and does not smell burnt. This requires raising the vehicle, getting it to operating temperature, and removing the fill plug.
3. Inspect the external transmission wiring harness and connectors for any visible damage, corrosion, or loose connections.
4. If fluid and external wiring are okay, the next step is to access the solenoids by draining the fluid and removing the transmission oil pan.
5. Once accessed, test the resistance of the TCC solenoid with a multimeter. According to a successful DIY repair, the specification is 3.5 ohms +/- 0.2 ohms. A reading outside this range confirms a bad solenoid. Other sources suggest a range of 4-7 ohms for similar transmissions, but the 3.5 ohm value is more specific to a user repair.
6. While the pan is off, inspect the internal wiring harness for brittleness, cracks, or signs of overheating.
7. If the solenoid and wiring test good, the issue may be with the Transmission Control Module (TCM), but this is highly unlikely.

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 confirmed by Kia's TSB. It is often described as the '2-6 Brake and Torque Converter Clutch' solenoid.
  Trusted brands: Kia/Hyundai (OEM), Dorman, Rostra
  OEM price range: $75-$150
  Aftermarket price range: $50-$100
• Automatic Transmission Fluid (OEM #Kia SP-IV) — The fluid must be drained to access the solenoid and should be replaced with the correct type to ensure proper transmission function. You will need 4-5 quarts for a drain and fill.
  Trusted brands: Kia (OEM), Idemitsu TLS-LV (SP-IV equivalent), Valvoline MaxLife Multi-Vehicle ATF
  OEM price range: $15-$25 per quart
  Aftermarket price range: $8-$15 per quart
• Automatic Transmission Pan Gasket (OEM #45283-3B010) — A new gasket is required to prevent leaks after reinstalling the transmission pan. Some technicians prefer using a high-quality RTV sealant designed for transmission fluid.
  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 a performance issue (stuck off) with the TCC, which can be caused by the same failing solenoid that triggers the P0743 electrical code. A real-world repair showed both codes present, which were resolved by replacing the TCC solenoid.
• P0748, P0753, P0758, P0763, P0768, P0773 — These are all electrical fault codes for other shift solenoids in the same transmission. The TSB #TSBTRA051R1 groups them together, suggesting a common failure pattern for the solenoids in this transmission.

Technical Service Bulletins (TSBs) & Recalls

• TSBTRA051R1: Provides information for replacing various shift solenoids, including the one related to P0743, on 6-speed automatic transaxles, advising against transaxle replacement. It covers a range of DTCs including P0743.

Platform-Specific Known Issues

• Kia issued Technical Service Bulletin #TSBTRA051R1 for multiple models including the Rio with the A6GF1 6-speed automatic transmission. It states that for DTCs like P0743, the corrective action is to replace the specific solenoid, not the entire transaxle.

Mechanic-Grade Diagnostic Values

• TCC Solenoid (VFS Type) Resistance — expected: 5.1 - 5.3 ohms. Failure: A reading significantly outside this range, especially an open circuit (infinite resistance) or short (near zero).
• Shift Solenoids (On/Off Type) Resistance — expected: 10 - 11 ohms. Failure: A reading outside this range. This is useful for confirming you are testing the correct solenoid type.
• TCC Solenoid (VFS Type) Current Draw (Live Data) — expected: Changes from ~50 mA at rest to ~850 mA when commanded ON by a scan tool.. Failure: Current does not change when commanded, or stays at zero, indicating an open circuit or faulty driver.
• Battery & Charging System Voltage — expected: 12.6-12.8V at rest, 13.8-14.6V while running.. Failure: Low voltage can cause the TCM to misinterpret sensor and solenoid signals, potentially setting electrical fault codes.

Scan Tool Commands That Help

• Kia GDS or equivalent professional scanner: Actuation Test / Output Test — To command the TCC solenoid on and off while monitoring live data (solenoid current, TCC slip RPM) to verify if the solenoid is responding electrically to commands from the TCM.
• Kia GDS or equivalent professional scanner: Resetting Adaptive Values — After replacing a solenoid or performing other transmission repairs, this function should be used to clear the learned shift adaptations and allow the TCM to relearn with the new components.

Wiring & Ground Locations

• Transmission Main Connector (TCC Solenoid Pins) — On the external case of the A6GF1 transmission.. To test the TCC solenoid and its wiring externally without removing the oil pan, you can check resistance across pins 10 (Solenoid Power) and 2 (TCC Solenoid Control). This quickly determines if the fault is internal (solenoid, internal harness) or external.
• Engine/Transmission Ground Strap — Typically a braided metal strap connecting the engine block or transmission case directly to the vehicle's chassis/frame.. A corroded, loose, or broken main ground strap can cause a variety of electrical issues, including erratic solenoid operation and fault codes like P0743, by creating an unstable ground reference for the control modules.

OEM Part Supersession History

• 46313-3B770 →
  Heads up: The OEM part 46313-3B770 is often described as the '2-6 Brake and Torque Converter Clutch' solenoid. This can be confusing, as other solenoids like 46313-3B075 are listed for the '2-6' brake function alone. It is critical to ensure the replacement part is specified for the TCC function for the A6GF1 transmission, as several solenoids in the valve body are physically similar but have different functions and pressure characteristics (Normally High vs. Normally Low).

Model Year Variations Within This Range

• 2012-2015: No significant variations affecting the P0743 code were found within this model year range for the Kia Rio with the A6GF1 transmission. The transmission and its common failure points appear consistent across this generation.