P0743 Torque converter clutch solenoid electrical fault

Torque converter clutch (TCC) solenoid circuit electrical

P0743 in short

P0743 means the computer sees an electrical fault in the torque converter clutch solenoid circuit. Damaged wiring or a failed solenoid are the usual causes; fluid problems and the control module are rarer. Some cars show only the light, while others shift harshly or slip, so get it checked soon.

The torque converter clutch solenoid lets the computer lock and unlock the clutch inside the torque converter. P0743 sets when the electrical side of that circuit is abnormal: an open, short or wrong voltage. It describes the electrical circuit, not a hydraulic or mechanical fault.

TroubleCodes.net lists wiring and connectors, the TCC solenoid, dirty or degraded fluid (rare) and the control module (uncommon) as causes, and suggests checking fluid condition, wiring and resistance, then commanding the solenoid with a scan tool. Hyundai and Kia bulletins treat P0743 as a solenoid code: Hyundai says incorrect solenoid operation may hold the transaxle in fail-safe, and Kia says to replace the solenoids when current or history codes are present rather than the transaxle.

An NHTSA complaint on a 2008 Ford Escape lists P0743 with P0732 and a wrench light after a loss of acceleration, and the owner was told it was an internal transmission problem. That is a single owner report.

Most likely causes

  1. Failed torque converter clutch solenoid

    Supported by vehicle data
    Why it ranks here
    TroubleCodes.net says that if the solenoid does not respond to a scan tool command with good wiring, the solenoid is likely defective. Hyundai TSB 09-AT-018 and Kia TSB TRA051R1 prescribe solenoid work for this code.
    What would change this
    Rises if the solenoid does not change state when commanded and its resistance is out of range. Falls if wiring faults are found.

  2. Damaged, corroded or disconnected wiring or connectors

    Common general cause
    Why it ranks here
    TroubleCodes.net lists damaged, corroded or disconnected wiring and connectors and suggests resistance and continuity tests.
    What would change this
    Rises if continuity or resistance tests fail or a wiggle test changes the reading. Falls if wiring tests good.

  3. Dirty or degraded transmission fluid

    Possible — needs testing
    Why it ranks here
    TroubleCodes.net lists degraded fluid as a rare cause and says to check fluid condition first; it also says to replace fluid and filter after a solenoid replacement.
    What would change this
    Rises if the fluid is burnt, dirty or contains debris. Falls if the fluid is clean at the right level.

  4. Failed transmission or engine control module (uncommon)

    Possible — needs testing
    Why it ranks here
    TroubleCodes.net lists the PCM or TCM as an uncommon cause.
    What would change this
    Rises if wiring and solenoid test good. Falls if either is faulty.
    How to test the transmission control module (tcm)

What to test first

Start at step 1. Each result tells you what it means and where to go next.

  1. Check the transmission fluid level and condition where your vehicle has a dipstick, and read the stored codes, noting any P0741, P0742 or P0744.

    Low riskTool: scan tool and dipstick (if fitted)

  2. Inspect the solenoid harness and connectors for damage, corrosion or a loose connection, and test continuity and resistance against specification.

    Use cautionTool: multimeter

    Warning:Transmission parts and fluid can be hot, and the vehicle must be safely supported to work underneath. Use jack stands, let it cool and disconnect the battery before unplugging connectors.

  3. Use a scan tool to command the solenoid on and off and see whether its status changes with the wiring known good.

    Best left to a shopTool: bidirectional scan tool

    Warning:Commanding transmission components on a running or moving vehicle can cause unexpected movement. Do it with the vehicle secured, in park, and leave solenoid replacement to a shop.

Symptoms

  • Check engine light on
  • Harsh gear shifts
  • Slipping during acceleration, or the engine stalling when stopping Gets more serious: stop and have it checked.
  • Transmission overheating Gets more serious: stop and have it checked.
  • Higher fuel use
  • Stuck in one gear (fail-safe) on some models Gets more serious: stop and have it checked.

Compare with: Check engine light with loss of power

How to fix

  1. Check the transmission fluid level and condition where the vehicle has a dipstick.

  2. Ask a dealer whether a bulletin applies to your VIN for P0743.

Parts and cost context

  • Transmission control module (TCM):The module is uncommon as a cause; TroubleCodes.net says to replace the solenoid, then the fluid and filter. Labour varies; get a quote.

Labor varies by vehicle and shop; get a quote before you approve a repair.

Compare used part prices on PartPriceGuide

On your vehicle

Hyundai

  • 1999–2010

    Supported by vehicle data

    Hyundai TSB 09-AT-018 says incorrect solenoid operation (including P0743) may hold the transaxle in third gear fail-safe on Sonata, Santa Fe, Elantra and Tucson. Whether the bulletin is still current is not verified.

  • TSB-09-AT-018Status unverified

    Automatic transaxle solenoid codes P0740 to P0770

    1999–2010sonata, santa-fe, elantra, tucson · issued · NHTSA 10032908

    Incorrect solenoid operation may light the check engine light and hold the transaxle in third gear fail-safe. Covers Sonata 1999-2010, Santa Fe 2001-2010, Elantra 2001-2006 and Tucson 2005-2009 in the NHTSA record.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

Kia

  • 2011–2015

    Supported by vehicle data

    Kia TSB TRA051R1 says to replace the solenoids rather than the transaxle when P0743 and related codes are present on 6-speed automatics. Whether the bulletin is still current is not verified.

  • TSBTRA051R1Status unverified

    6-speed automatic solenoid replacement, multiple DTCs

    2011–2015sedona, sportage, sorento, forte, optima · issued · NHTSA 10089761

    Replace the solenoids if current or history codes P0741, P0743, P0748 and others are present, and do not replace the transaxle. Can be done with the transaxle in the car.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

Ford

  • 2008 · Escape

    Possible — needs testing

    An NHTSA complaint on a 2008 Escape lists P0743 with P0732 and a wrench light after a loss of acceleration; the dealer called it an internal transmission problem. Owner report only.

  • P0741Torque converter clutch not engaging as commanded

    Same system Supported by vehicle data

    Hyundai and Kia solenoid bulletins list P0741 (performance or stuck off) with P0743.

  • P0742Torque converter clutch stuck on

    Same system Supported by vehicle data

    Hyundai TSB 09-AT-018 lists P0742 (stuck on) with P0743.

  • P0744Torque converter clutch control signal dropping in and out

    Same system Possible — needs testing

    The torque converter clutch circuit family includes P0744 (intermittent), listed beside P0743 in the Delaware code list.

All Transmission codes

P0743 questions

What does P0743 mean?

The torque converter clutch solenoid circuit has an electrical fault: an open, short or wrong voltage.

Do I need a new solenoid?

Check the wiring and fluid first. If wiring is good and the solenoid does not respond to a scan tool command, the solenoid is likely bad.

Can I drive with P0743?

Some cars show only the light. If the car slips, shifts harshly or overheats, get it checked soon.

Sources and review

  1. P0743 - Torque converter clutch solenoid - electrical — TroubleCodes.net
  2. Hyundai TSB 09-AT-018 (NHTSA 10032908) — Hyundai Motor America ,
  3. Kia TSB TRA051R1 (NHTSA 10089761) — Kia Motors America ,
  4. On-Board Diagnostic Trouble Codes (generic code title list) — Delaware Division of Motor Vehicles
  5. NHTSA complaint 10592613: 2008 Ford Escape — NHTSA Office of Defects Investigation
Last reviewed
Written by
Saurabh K.
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