P0740 on 2012-2014 Acura TL: Torque Converter Clutch Circuit Malfunction Guide

What's Unique About the 2012-2014 Acura TL

While the P0740 code was a notorious sign of catastrophic transmission failure on older (1999-2003) Acura TL models, this is generally not the case for the fourth-generation (2009-2014) TL. On these later models, which use a more robust 6-speed automatic transmission (on most models), the issue is more commonly linked to serviceable components like the transmission fluid or the TCC solenoid itself, rather than widespread internal clutch failure. A full transmission replacement is a much less frequent outcome for this code on the 2012-2014 models compared to their predecessors. However, it's important to note that deteriorated fluid can cause torque converter judder, which Acura has addressed with TSBs involving fluid flushes and software updates.

Symptoms You May Notice

• Check Engine Light is on
• Vehicle fails to shift into the highest gear or seems to 'slip' at highway speeds
• Reduced fuel economy
• Engine RPM is higher than usual at highway speeds (e.g., above 2500 RPM at 65 mph)
• Vehicle may shudder or stall when coming to a stop (if the TCC is stuck engaged)
• Harsh or delayed shifts
• Flashing "D" indicator light on the dashboard

Most Likely Causes

1. Low or Dirty Transmission Fluid 🔴 High Probability → Shop Transmission Assembly Honda/Acura automatic transmissions are sensitive to fluid level and condition. Old, degraded fluid can cause solenoids to stick or passages to become restricted. Acura issued TSBs (16-046, 18-047, 18-048) for this generation TL specifically for torque converter judder caused by deteriorated ATF, which can be a precursor to other issues.
   How to confirm: Check the transmission fluid dipstick (engine off, on level ground) for level and color. The fluid should be red/pink and not smell burnt. If it is dark brown/black or low, it needs service.
   Typical fix: Perform three consecutive transmission drain-and-fills using only genuine Acura/Honda ATF DW-1 fluid. This method replaces a majority of the old fluid without using a pressurized flush machine, which can dislodge debris and cause more harm.
   Est. part cost: $40-$80 for fluid
2. Faulty Torque Converter Clutch (TCC) Solenoid 🟡 Medium Probability → Shop Automatic Transmission Torque Converter The solenoid can fail electrically over time or its internal screens can become clogged with normal clutch material, preventing proper operation. This is a very common failure point on Honda/Acura 5 and 6-speed automatics.
   How to confirm: A mechanic can test the solenoid's resistance with a multimeter to see if it's within the manufacturer's specifications (typically 12-25 ohms for this type of solenoid). They can also apply 12V power to it to check for a mechanical 'click'. 🎬 Watch: Easy way to test the TCC solenoid
   Typical fix: Replace the TCC solenoid assembly and the related gasket. On these transmissions, it is often part of a linear solenoid assembly located on the exterior of the transmission case, making it accessible after removing the battery and air intake components. 🎬 Watch: How to remove and clean the dual linear solenoid
   Est. part cost: $100-$350
3. Wiring or Connector Issues ⚪ Low Probability The wiring harness to the transmission can be exposed to heat and debris, potentially causing corrosion or damage over time, especially at the connector.
   How to confirm: Visually inspect the wiring harness and connectors leading to the TCC solenoid for any signs of damage, corrosion, or loose connections. A continuity test can be performed on the circuit from the PCM/TCM to the solenoid connector.
   Typical fix: Repair or replace the damaged section of the wiring harness or clean the connectors with electrical contact cleaner.
   Est. part cost: $10-$100

Rare But Worth Checking

• Failing Torque Converter: → Shop Automatic Transmission Torque Converter While less common on this generation, an internal failure of the torque converter's lock-up clutch can cause this code. This is often accompanied by significant shuddering or excessive metallic debris in the transmission fluid. Acura TSBs indicate that judder is often a fluid issue, not a hard part failure.
• Internal Transmission Failure: → Shop Transmission Assembly In rare cases, excessive debris from failing internal clutches can clog the TCC solenoid and fluid passages, leading to the code. This is a much more serious issue requiring a transmission rebuild or replacement and was the primary failure mode on older TLs. NHTSA ODI #10392049 describes a case where a dealer identified code P0740 as an internal transmission failure requiring a full replacement.
• Faulty Powertrain Control Module (PCM): → Shop Engine Control Module (ECM) It is very rare for the PCM itself to be the cause of the problem. All other possibilities, especially fluid, solenoid, and wiring, should be exhausted before considering PCM replacement.

Diagnosis Steps

1. Check the transmission fluid level and condition. If low, top it off with Acura ATF DW-1 and check for leaks. If dirty or burnt, perform a 3x drain-and-fill procedure.
2. Scan the computer for any other transmission-related codes that could provide more clues.
3. Inspect the wiring harness and connector for the TCC solenoid for any visible damage, corrosion, or loose connections.
4. If the fluid and wiring are good, test the TCC solenoid. This involves checking its electrical resistance with a multimeter (should be in the 12-25 ohm range) and listening for a click when applying 12V power.
5. If the solenoid tests bad, replace it along with its gasket/o-rings.
6. If the solenoid tests good, the issue may be a clogged passage in the valve body, a failing torque converter, or a rare internal transmission problem requiring professional diagnosis, which may include a line pressure test.

Parts You'll Likely Need

• Acura ATF DW-1 Automatic Transmission Fluid (OEM #08200-9008A) — Correct, clean fluid is the first and most critical step for resolving transmission issues on these vehicles. Using non-OEM fluid is not recommended.
  Trusted brands: Acura (Genuine OEM)
  OEM price range: $10-$15 per quart
• Torque Converter Clutch (TCC) Solenoid Assembly (OEM #28260-RDK-023 (This is a common part number for the linear solenoid assembly on this platform, but always verify with VIN)) — This solenoid is the most common component to fail within the TCC circuit, either electrically or by becoming clogged.
  Trusted brands: Acura (OEM), Rostra, Standard Motor Products (SMP)
  OEM price range: $250-$350
  Aftermarket price range: $100-$200

Related Codes That Often Appear With This One

• P0741 — This code indicates 'Torque Converter Clutch Circuit Performance or Stuck Off,' which is a closely related hydraulic/mechanical fault within the same system. P0740 is an electrical circuit fault, while P0741 points to the mechanical result of that fault (or a hydraulic blockage).

Technical Service Bulletins (TSBs) & Recalls

• TSB 16-046 / 18-047 / 18-048: Addresses a judder from the torque converter lock-up clutch between 20-60 mph. The cause is identified as deteriorated ATF, and the fix is a software update and a transmission fluid flush.

Platform-Specific Known Issues

• Torque Converter Judder/Shudder: → Shop Automatic Transmission Torque Converter Many 2012-2014 TLs experience a judder or shudder while driving between 20-60 mph. Acura TSB 16-046 (later replaced by 18-047 and 18-048) identified this as being caused by deteriorated transmission fluid, not a faulty torque converter. The fix involves a software update and flushing the transmission fluid three times. This condition is related to the TCC operation and can be a precursor to the P0740 code if the fluid condition worsens.

Mechanic-Grade Diagnostic Values

• Torque Converter Clutch (TCC) Solenoid Resistance — expected: 12 - 25 Ohms. Failure: A reading of infinite resistance (open circuit) or near-zero resistance (short circuit) indicates a failed solenoid.

Scan Tool Commands That Help

• Honda Diagnostic System (HDS) or equivalent professional bidirectional scanner: TCC Solenoid ON/OFF Test (Active Test) — This command is used after verifying fluid and wiring integrity. It directly commands the PCM/TCM to activate and deactivate the TCC solenoid. A technician can monitor live data (like TCC slip RPM) to see if the solenoid is responding to the command. This helps isolate a faulty solenoid from a hydraulic blockage or a bad PCM driver.
• Honda Diagnostic System (HDS): SHIFT SOL TEST in MISCELLANEOUS TEST MENU — This function can be used to run a diagnostic sequence on various transmission solenoids, including the TCC solenoid, to check for electrical integrity and response.

OEM Part Supersession History

• 28260-RDK-013 → 28260-RDK-023 — Standard part revision and update by the manufacturer.
  Heads up: The parts are generally interchangeable.
• 28260-RDK-023 → 28260-R97-003 — Part update and consolidation across multiple Honda/Acura models.
  Heads up: This is listed as a valid supersession by some suppliers, but it is always critical to verify the correct part number with the vehicle's VIN before ordering.

Model Year Variations Within This Range

• 2012-2014: For the 2012 model year, Acura replaced the previous 5-speed automatic transmission with a new, more robust 6-speed automatic. This is a key reason why P0740 is less likely to indicate catastrophic failure on these specific years compared to earlier 2009-2011 models.
• 2012-2014: As part of the 2012 update, all TL models received an external transmission fluid cooler, a feature previously reserved for SH-AWD models. This helps with thermal management and may contribute to the increased longevity of the 6-speed transmission.

Diagnostic Flowchart

Other Known Issues on This Vehicle

Issues unrelated to this code that are worth knowing about as an owner of this generation:

• Excessive Oil Consumption (3.7L V6) 🔴 High — Common on the 3.7L J37 engine. Acura acknowledged the issue and extended the powertrain warranty (TSB 19-006) due to carbon buildup on oil control rings. Owners report needing to add oil between changes. (Ref: TSB 19-006)
• Torque Converter Judder/Shudder 🟠 Medium → Shop Automatic Transmission Torque Converter — Widespread enough to warrant multiple TSBs. A shudder is felt between 20-60 mph. It is caused by deteriorated ATF, not a failed torque converter. (Ref: TSB 16-046, 18-047, 18-048)
• Propeller Shaft Whine (SH-AWD models) 🟠 Medium — A common complaint on SH-AWD models where a whining or whistling noise that changes with road speed emanates from the center of the car. It's caused by a failing center support bearing on the propeller (drive) shaft, which requires replacing the entire shaft assembly.

Used vs. New Parts: Buying Guide for This Vehicle

When a used part is the smart pick: A used wiring harness pigtail or a complete transmission harness can be a good value if the part is visually inspected for corrosion, brittle wires, or damaged connector locks. For major electronic components like the TCC solenoid, used parts are not recommended due to their unknown history and high failure rate.

Donor-vehicle mileage cap: roughly under 80000 miles for the part to have meaningful remaining life.

What to inspect on the donor part:

• For wiring, check for any signs of cracking, melting, or previous repairs (e.g., tape, butt connectors).
• Ensure all connector pins are straight and free of green or white corrosion.
• Verify the donor vehicle is from a dry climate to minimize the risk of corrosion.

OEM-only on this vehicle (don't cheap out):

• Torque Converter Clutch (TCC) Solenoid Assembly: While some aftermarket options exist, the general consensus for Honda/Acura transmissions is that OEM solenoids offer the highest reliability and are worth the extra cost to avoid repeat repairs.
• Automatic Transmission Fluid (ATF): Strictly use Honda/Acura ATF DW-1. Using universal or incorrect fluid is a leading cause of shifting problems and component failure.

Aftermarket brands forum-validated for this vehicle:

• Standard Motor Products (SMP)
• Rostra

Brands owners have reported issues with on this vehicle:

• Unbranded, low-cost solenoids from online marketplaces are a significant gamble and have a high rate of premature failure.

Real Owner Stories

Aggregated from forums and TSBs cited above. Mileages and costs reflect what owners reported in those sources.

Documented NHTSA Reports

Related OBD-II Codes

• P0700 — A general transmission control system malfunction code that often accompanies P0740 to trigger the Check Engine Light.
• P0741 — Related to torque converter clutch performance or being stuck off, often sharing the same root causes like degraded ATF DW-1 or a faulty linear solenoid.
• P1750 — A Honda/Acura specific code for mechanical problems in the hydraulic control system, often related to the same solenoid or fluid passage issues mentioned in the context.
• P1751 — Often appears alongside P0740 when there are shift solenoid performance issues or hydraulic circuit restrictions.

Frequently Asked Questions