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P0740 on a 2017 Honda Civic

Torque Converter Clutch Circuit Fault

P0740 on a 2017 Honda Civic indicates torque converter clutch circuit fault. It usually stays drivable short-term but should be diagnosed promptly. The most common cause is failed tcc solenoid (typically $300–$900). Confirm the root cause before replacing parts.

Severity: high Safe to drive (short term) Compact Sedan

Reviewed by MECH AI Editorial · Last verified · Includes 20 active NHTSA TSBs

What does P0740 mean on a 2017 Honda Civic?

P0740 is the general torque converter clutch (TCC) circuit code. Depending on the manufacturer it is set for an electrical fault in the TCC solenoid circuit — an open or a short — or for the clutch simply never engaging when the transmission controller commands it. The torque converter clutch is what mechanically locks the engine to the transmission at cruise, removing the slip that a fluid coupling always has. When it does not work, the engine turns faster than it should for a given road speed, fuel economy drops, and the transmission runs hotter than it was designed to.

The symptoms, causes, and diagnostic steps below describe P0740 itself, so they read the same on nearby Honda Civic model years. Powertrain and trim details vary year to year — confirm the specifics against your own vehicle before buying parts.

Is it safe to drive a 2017 Honda Civic with P0740?

In most cases a 2017 Honda Civic stays drivable for short trips with P0740 active, but diagnose and repair it promptly. This is a high-severity code — ignoring it can lead to further damage or a failed emissions test.

What are the symptoms of P0740 on a 2017 Honda Civic?

What causes P0740 on a 2017 Honda Civic?

Cause Likelihood Estimated repair (USD)
Failed TCC solenoid Most common $300–$900
Damaged wiring or fluid-contaminated external transmission connector Common $100–$500
Low transmission fluid level or contaminated fluid Common $100–$400
Stuck TCC control valve in the valve body Common $400–$1,500
Worn or burned torque converter clutch friction material Requires torque converter replacement — a major job. Occasional $1,800–$4,500
Failed TCM or PCM driver for the TCC circuit Rare $500–$1,500
Internal transmission damage allowing fluid bypass Rare $2,500–$6,500

Cost ranges are editorial estimates for parts and labor at an independent U.S. shop — not quotes. What you actually pay moves with your region, the shop's hourly rate, which engine you have, and how much diagnostic time the job takes. Dealer service departments typically sit above these ranges.

How to diagnose this on a 2017 Honda Civic

  1. Check transmission fluid level and condition

    This comes first every time. Many modern transmissions have no dipstick and require a specific procedure — fluid at a defined temperature, engine running, vehicle level — to check the level at all. Follow the procedure for this vehicle. Fluid that smells burnt or carries clutch material tells you the problem is internal and no solenoid will fix it.

    Tools: Vehicle-specific service procedure, Replacement fluid (if needed)

  2. Pull all transmission codes, not just the engine codes

    P0740 on its own is one repair scope. P0740 alongside gear-ratio codes or a pressure code means broader problems that a solenoid replacement will not resolve. Read the TCM directly rather than relying on a generic scan of engine codes only.

    Tools: Scan tool with TCM access

  3. Watch TCC command against actual lockup on the road

    At a steady highway cruise, graph commanded TCC state alongside engine RPM and vehicle speed. On a healthy system the RPM drops noticeably at the moment lockup engages. Command with no RPM drop confirms the clutch is not engaging mechanically — which is the condition, not yet the cause.

    Tools: Scan tool with TCC and live RPM PIDs

  4. Test the TCC solenoid circuit electrically

    Locate the TCC solenoid pin at the external transmission connector using the wiring diagram, and measure resistance. Compare against the specification for this transmission. Infinite resistance means an open coil or an open circuit; a near-zero reading means a shorted solenoid.

    Tools: Multimeter, Wiring diagram

  5. Inspect the external transmission connector for fluid

    A failed case seal lets transmission fluid wick up inside the wiring harness and into the connector. The result mimics a failed solenoid on a multimeter while the solenoid is perfectly fine. If you find fluid in the connector, the repair is the seal and often a section of harness.

    Tools: Connector unlock tool, Flashlight

Known Technical Service Bulletins for the 2015-2019 Honda Civic

Manufacturers publish Technical Service Bulletins (TSBs) when a known issue affects a specific vehicle. These bulletins come from the NHTSA database for your Honda Civic.

+14 more TSBs available in MECH AI's TSB explorer for this vehicle.

NHTSA complaints & recalls for the 2017 Honda Civic

Owner-reported safety complaints and official recalls filed with the U.S. National Highway Traffic Safety Administration for the 2017 Honda Civic. Use these to gauge how common a problem is on your specific vehicle before you start chasing Honda Civic diagnostics.

569 owner complaints
22 involved a crash
6 involved a fire
11 reported injuries
  • ENGINE 65
  • STEERING 161
  • UNKNOWN OR OTHER 160
  • ELECTRICAL SYSTEM 99
  • SERVICE BRAKES 35

6 active recalls

  • STEERING:ELECTRIC POWER ASSIST SYSTEM Sep 2018

    Honda (American Honda Motor Co.) is recalling certain 2017-2018 Honda Civic and CR-V vehicles. The magnet that controls the torque sensor output signal for the electronic power steering system may not be properly secured, allowing the magnet to become dislodged. During a full…

    NHTSA campaign 18V663000
  • EQUIPMENT:OTHER:OWNERS/SERVICE/OTHER MANUAL Nov 2018

    Honda (American Honda Motor Co.) is recalling certain 2017-2018 Honda Civic Hatchback and Civic Type R vehicles. The owners guide in these vehicles may not have been included or if included, the owner's guide may not have been properly provided required information. As such, t…

    NHTSA campaign 18V817000
  • AIR BAGS Apr 2018

    Honda (American Honda Motor Co.) is recalling certain 2017 Honda Civic Hatchback and Civic Type R vehicles. Driver and front passenger seatback pads sold as replacement service parts were made without slit openings for the seat-mounted side air bags. In the event of a crash nece…

    NHTSA campaign 18V266000
  • POWER TRAIN:DRIVELINE:DRIVESHAFT Nov 2017

    Honda (American Honda Motor Co.) is recalling certain 2017 Honda Civic Sedan and Coupe vehicles. The right halfshaft may have been improperly heat treated, reducing its strength.…

    NHTSA campaign 17V706000

How do I fix P0740 on a 2017 Honda Civic?

Engines in the 2017 Honda Civic

The 2017 Honda Civic was offered with the 1.5L 4-cylinder and 2.0L 4-cylinder engines. Which one you have changes where P0740 is most likely to originate, so confirm your engine before ordering parts.

Engine data: EPA fueleconomy.gov.

P0740, P0741, P0743 — three codes, one system

The torque converter clutch codes describe different aspects of the same failure, and manufacturers are not perfectly consistent about which one they set:

CodeWhat it describes
P0740General TCC circuit fault — electrical or “never engages”
P0741TCC performance, or stuck off — commanded but slipping
P0742TCC stuck on — will not release, stalls at stops
P0743TCC circuit electrical fault specifically
P0744TCC circuit intermittent

Because P0740 is the broad one, the same physical fault might show up as P0740 on one vehicle and P0743 on another. Do not read too much into which number appeared; read the live data instead.

What no lockup feels like from the driver’s seat

The clearest tell is highway RPM. A vehicle that used to cruise at 2,000 RPM at 70 mph and now sits noticeably higher at the same speed is running without lockup. The engine is spinning the converter’s fluid rather than being bolted to the transmission through the clutch.

The second tell is that the familiar sensation of a final “shift” at around 45–55 mph is gone. That was never a gear change — it is the lockup clutch engaging. Its absence is P0740’s signature symptom.

The third is fuel economy. Converter slip at highway speed costs real miles per gallon, which is why this code often shows up as “my mileage suddenly got worse” before anyone notices the light.

Fluid first, always

Low or degraded fluid causes hydraulic problems that look exactly like electrical ones, and it is the cheapest thing on the list to correct. Check it before touching a solenoid.

One old piece of advice deserves updating: for decades the rule was never to change the fluid in a transmission that is already misbehaving, on the theory that fresh fluid washes out accumulated material and finishes the job. With modern fluids, a drain-and-fill using the correct OEM specification is generally safe and sometimes resolves the code outright. A high-pressure machine flush on a transmission that is already slipping is still a risk worth avoiding.

When to hand this to a transmission shop

Fluid level, connector inspection, and a resistance check at the external connector are all reasonable driveway jobs. Once the diagnosis points inside — a stuck valve in the valve body, or clutch material on the pan magnet — you are into a job that needs a lift, a fluid handling setup, and transmission-specific experience. That is a good moment to stop and get a quote rather than to keep going.

P0740 on a 2017 Honda Civic: frequently asked questions

What does diagnostic trouble code P0740 mean on a 2017 Honda Civic?

P0740 is the general torque converter clutch (TCC) circuit code. Depending on the manufacturer it is set for an electrical fault in the TCC solenoid circuit — an open or a short — or for the clutch simply never engaging when the transmission controller commands it. The torque converter clutch is what mechanically locks the engine to the transmission at cruise, removing the slip that a fluid coupling always has. When it does not work, the engine turns faster than it should for a given road speed, fuel economy drops, and the transmission runs hotter than it was designed to.

What are the symptoms of P0740 on a 2017 Honda Civic?

Check Engine Light is illuminated. Engine RPM at highway cruise is higher than normal for the same speed. Noticeable fuel economy drop, worst on the highway. No sensation of the transmission "shifting" into lockup at cruise. Transmission fluid running hot, especially when towing. Often paired with P0700 from the transmission controller

What causes P0740 on a 2017 Honda Civic?

Failed TCC solenoid (most-common). Damaged wiring or fluid-contaminated external transmission connector (common). Low transmission fluid level or contaminated fluid (common). Stuck TCC control valve in the valve body (common). Worn or burned torque converter clutch friction material (occasional). Failed TCM or PCM driver for the TCC circuit (rare). Internal transmission damage allowing fluid bypass (rare)

Is it safe to drive a 2017 Honda Civic with P0740?

In most cases a 2017 Honda Civic stays drivable for short trips with P0740 active, but it should be diagnosed and repaired promptly — this is a high-severity code. Ignoring it can lead to further damage or a failed emissions test.

Related diagnostic codes

P0740 on other Honda Civic model years