P0748 on 2011-2014 Kia Sedona: Pressure Control Solenoid 'A' Electrical Fault Guide

What's Unique About the 2011-2014 Kia SEDONA

For this generation of Kia Sedona with the 6-speed automatic transmission (part of the Hyundai/Kia A6 family, likely the A6LF2 variant), a known issue is the failure of individual shift solenoids. Kia acknowledged this by issuing Technical Service Bulletin (TSB) #TSBTRA051R1, which specifically lists P0748. The bulletin advises technicians to replace the faulty solenoids rather than the entire, much more expensive, transmission assembly. This makes the diagnosis more direct and the repair more affordable than it might be on other vehicles where a full transmission replacement is the common recommendation.

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
• Harsh, erratic, or delayed shifting
• Vehicle enters "limp mode" (gets stuck in a single gear, often 3rd)
• Transmission slipping
• Engine stalling when stopped or at idle
• Decreased fuel economy
• Transmission overheating

Most Likely Causes

1. Failed Pressure Control Solenoid 'A' 🔴 High Probability → Shop Transmission Valve Body This is a known issue for Kia's 6-speed automatic transmissions, as documented in TSB TSBTRA051R1. The solenoids are subject to wear and failure from heat and contaminated fluid.
   How to confirm: A technician can perform an actuation test using a diagnostic scan tool (like Kia's GDS) to command the solenoid on and off. The solenoid's internal resistance can also be measured with a multimeter; an open or shorted reading confirms failure. The specified resistance is typically 5.0 to 5.6 Ω at 20°C (68°F). A reading outside this range indicates a faulty solenoid.
   Typical fix: Replace the faulty solenoid or the entire solenoid pack, which is located inside the transmission on the valve body. Many technicians recommend replacing the entire set of 8 solenoids as a preventative measure since they are of the same age and have been subjected to the same conditions.
   Est. part cost: $75-$150
2. Damaged Wiring or Connectors 🟡 Medium Probability The wiring harness leading to or inside the transmission can become damaged, corroded, or develop a loose connection over time. The internal harness, often a flexible ribbon-style connector, is a known weak point due to constant exposure to heat and fluid.
   How to confirm: Visually inspect the external transmission harness and connectors for damage. Check for continuity and shorts on the wiring circuit between the TCM and the transmission connector. Testing for continuity from the main connector pins to each solenoid's connector pin can identify an open circuit in the internal harness.
   Typical fix: Repair the damaged section of the external wiring harness or clean/replace the corroded connector. If the internal harness has failed, it must be replaced. This part is often replaced along with the solenoids.
   Est. part cost: $10-$100
3. Low or Contaminated 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, red in color, and free of debris or a burnt smell. Note: This transmission has no dipstick and must be checked via a fill plug when the vehicle is level and at a specific operating temperature.
   Typical fix: Perform a transmission fluid and filter change using Kia SP-IV compatible fluid. If the fluid is very dirty or contains metal shavings, it may indicate a more severe internal problem.
   Est. part cost: $50-$120

Rare But Worth Checking

• Faulty Transmission Control Module (TCM): → Shop Transmission Assembly A TCM failure is rare but possible. The output driver for the solenoid circuit can fail. In some Hyundai/Kia models, a specific power management IC chip (e.g., TLE6288R) on the control board has been known to fail, causing P0748. This should only be considered after all other possibilities (solenoid, wiring, fluid) have been thoroughly ruled out.

Diagnosis Steps

1. Check the transmission fluid level and condition. Ensure it is clean and full. This requires the vehicle to be level and at a specific temperature to check via the side fill plug.
2. Scan the TCM for any other related trouble codes. Note all codes present, especially if other solenoid codes are stored.
3. Visually inspect the external transmission wiring harness and the main round connector for any signs of damage, corrosion, or loose connections.
4. Using a professional scan tool, perform an actuation test on the Pressure Control Solenoid 'A' to see if it responds to commands.
5. If the solenoid does not respond, disconnect the transmission connector and use a multimeter to test the resistance of the solenoid's circuit. Compare the reading to the manufacturer's specification (typically around 5.0-5.6 Ω). An out-of-spec reading (open or short) indicates a faulty solenoid or internal wiring.
6. If the solenoid resistance is within spec from the external connector, the issue may be intermittent. The next step is to gain access to the solenoid itself by dropping the transmission pan and valve body to test the solenoid directly and inspect the internal wiring harness.
7. If wiring and the solenoid test good, the issue may be a more complex internal transmission problem or a faulty TCM, which requires advanced diagnostics.

Parts You'll Likely Need

• Automatic Transmission Control Solenoid (OEM #46313-3B600) — This is the most common failure part for code P0748 on this vehicle, as identified by Kia's own service bulletin. This part number is widely used across many Kia/Hyundai 6-speed transmissions for various solenoid functions.
  Trusted brands: Kia (Genuine OEM), Standard Motor Products, Wells, Rostra
  OEM price range: $80-$120
  Aftermarket price range: $65-$150
• Internal Transmission Wiring Harness (OEM #46307-3B650 (example, verify with VIN)) — The internal ribbon-style harness is a known failure point and is often replaced preventatively with the solenoids.
  Trusted brands: Kia (Genuine OEM)
  OEM price range: $50-$100
  Aftermarket price range: $40-$80

Related Codes That Often Appear With This One

• P0700 — This is a general Transmission Control System Malfunction code. It is an informational code indicating that a specific fault code, like P0748, is stored in the TCM.
• P0741 — Relates to the Torque Converter Clutch (TCC) solenoid, which works in conjunction with pressure control solenoids.
• P0743 — Another TCC solenoid electrical fault code. A shared wiring, power, or TCM issue could trigger both P0748 and P0743.
• P0753, P0758, P0763, P0768, P0773 — These are electrical fault codes for other shift solenoids (A, B, C, D, E). The TSB groups all these codes together, suggesting a common failure pattern of the solenoids or their shared internal wiring harness.

Technical Service Bulletins (TSBs) & Recalls

• TSBTRA051R1: Provides information on replacing various shift solenoids for a list of DTCs including P0748 on 6-speed automatic transaxles, advising against transaxle replacement.

Platform-Specific Known Issues

• Kia issued Technical Service Bulletin TSBTRA051R1 for multiple models with the 6-speed automatic transmission, including the Sedona. It states that for DTC P0748 (and several other solenoid codes), the fix is to replace the solenoids, not the entire transaxle.
• The A6-family of transmissions (A6GF1, A6MF1/2, A6LF1/2/3) used across the Hyundai/Kia lineup from roughly 2009 onwards are known for solenoid and internal harness failures as they age. The 2011-2014 Sedona with the 3.5L V6 engine typically uses the A6LF2 transmission.

Mechanic-Grade Diagnostic Values

• Pressure Control Solenoid (PWM type) Coil Resistance — expected: 5.0 to 5.6 Ω at 20°C (68°F). Failure: An open circuit (infinite resistance) or a short circuit (near zero resistance).
• On/Off Type Shift Solenoid Coil Resistance — expected: 10 to 11 Ω. Failure: A reading significantly outside this range, open, or shorted. This helps differentiate between solenoid types during testing.
• Solenoid Circuit to Ground Resistance — expected: 1 MΩ or higher. Failure: A low resistance reading indicates a short to ground in the solenoid or wiring.
• Solenoid Supply Voltage — expected: 12 V ± 1 V when commanded ON by the TCM. Failure: Absence of voltage or significantly low voltage when the solenoid should be active points to a wiring or TCM driver issue.
• Valve Body Solenoid Bolt Torque — expected: 12 Nm (8.8 ft-lbs). Failure: N/A - This is a specification for reassembly.

Scan Tool Commands That Help

• Kia GDS (or compatible advanced scan tool like Autel): Resetting Auto T/A Values / Resetting Adaptive Values — This function is mandatory after replacing transmission solenoids, the valve body, or the entire transmission. It clears the learned values from the TCM.
• Kia GDS (or compatible advanced scan tool): Adaptive Value Relearn Procedure (Drive Cycle) — Immediately after resetting the adaptive values. The TCM must relearn the correct hydraulic pressures and shift timing. The procedure involves a specific drive cycle: warming the fluid, performing 3-5 gentle accelerations through 1st-3rd gears at ~30% throttle, followed by static shifts between P-R-N-D.

Wiring & Ground Locations

• External Transmission Connector — On the outside of the transmission case. It's a large, round connector.. This is the primary diagnostic point for testing all internal transmission electrical components (solenoids, sensors) from outside the transmission, helping to isolate a fault to the external harness, internal harness, or a component without removing the oil pan.
• Transmission Ground Strap — A braided metal strap connecting the transmission case to the vehicle's chassis or engine block.. A poor or corroded ground connection can cause erratic voltage readings and floating grounds for all transmission sensors and solenoids, potentially triggering false electrical fault codes like P0748.
• Solenoid SL1 Circuit Pins — Within the main external transmission connector. Some diagrams for this transmission family identify these as Pin 5 (SL1+) and Pin 10 (SL1-).. Knowing these specific pins allows a technician to directly measure the resistance of the Pressure Control Solenoid 'A' circuit from the external connector. Note: Pinouts should always be confirmed with a vehicle-specific wiring diagram.

Real Owner Repair Stories

• AliExpress User Review / Guide (Hyundai with related A6 family transmission) — Intermittent check engine light with P0748, slipping between 2nd and 3rd gear when cold.
  ❌ Tried (didn't work) Changing the ATF (twice), Replacing all external shift solenoids with known-good used parts
  ✅ What actually fixed it The owner diagnosed and replaced a faulty power management IC chip on the ECU/TCM circuit board. The board was removed from the vehicle and the chip was desoldered and replaced, which resolved the P0748 code and shifting issues.