OBD-II trouble code
P0740: Torque Converter Clutch Circuit Malfunction / Open
The PCM has found an electrical problem in the torque converter clutch solenoid circuit — an open or shorted winding, a bad connector, or damaged wiring. Where P0741 means the clutch isn't locking (a performance fault), P0740 means the circuit that commands it has an electrical fault.
Quick facts
- System
- Powertrain
- Category
- Transmission / Torque Converter
- Severity
- Medium severity
- Drivable
- Usually safe to drive short-term
- Repair cost range
- $300 – $900 (torque converter clutch solenoid replacement)
- DIY difficulty
- Shop recommended
Browse every code in P0700–P0799, or start from the full code library.
What does P0740 mean?
P0740 is the electrical-circuit member of the torque converter clutch family, and the comparison is with its sibling P0741. P0741 is a performance code: the clutch is commanded to lock and the RPM signature shows it's still slipping — a mechanical or hydraulic shortfall. P0740 is a circuit code: when the PCM electrically tests the TCC solenoid circuit, it finds a problem in the wiring itself — an open winding, a short, an out-of-range resistance, or a missing return signal. In other words, P0741 says 'the clutch didn't do its job'; P0740 says 'I can't drive the clutch's solenoid properly in the first place.'
The torque converter clutch is a small lockup clutch inside the converter that mechanically couples the engine to the transmission once you're cruising, eliminating the slip a converter normally has. That lockup is what lets the engine settle into low RPM on the highway and deliver the fuel economy on the window sticker. The PCM controls it by switching current through the TCC solenoid in the valve body. P0740 sets when the electrical path to that solenoid fails the PCM's self-check: the solenoid coil has gone open or shorted, the connector has corroded, a wire has chafed or broken, or the PCM's driver circuit has failed.
Because it's an electrical fault, the list is the wiring and the solenoid coil. Fluid condition is a separate check. An open or shorted TCC solenoid coil and a damaged connector or harness are both on the list. The connector is checked first because it is outside the pan. That order is not a published count of which one fails. Worn solenoids, internal valve-body wiring, and PCM driver faults round it out. Drivers may notice the same things as P0741 — no lockup, so slightly worse highway fuel economy, cruise RPM that sits higher than it used to, and sometimes no overdrive feel — because the end result is the same lost lockup, just reached through an electrical fault instead of a mechanical one. The transmission can still shift cleanly through the gears.
Common causes
- Corroded or damaged TCC solenoid connector — the check the page's own first test looks for
- Moisture or fluid intrusion into the solenoid connector
- Recent transmission service where the internal harness wasn't reconnected properly
- Broken, chafed, or shorted wiring to the solenoid
- Electrically open or shorted TCC solenoid coil, after the connector and the harness have been checked
- Worn TCC solenoid that's begun to fail electrically
- Internal valve-body wiring or harness fault
- Failed PCM driver circuit for the TCC solenoid, after the connector, harness, and coil have been checked
Symptoms
- Check engine light on with P0740 stored
- Torque converter clutch never locks up
- Highway fuel economy lower than before, with the converter not locking
- Engine RPM sits higher than usual at steady cruise speeds
- No noticeable shift into 'overdrive lockup' on the highway
- Possible harsher feel as the converter never couples
- Transmission otherwise shifts through all gears normally
Diagnostic steps
- 1.Scan and note whether P0740 is present alone or with P0741/P0742/P0743. P0740 specifically flags an electrical-circuit fault, which steers you toward wiring and the solenoid coil.
- 2.Inspect the TCC solenoid connector for corrosion, fluid intrusion, or backed-out pins — a frequent and cheap cause.
- 3.Resistance-check the TCC solenoid against the manufacturer's spec. The figure varies widely by transmission — a simple on/off solenoid reads considerably higher than a pulse-width-modulated one — so the manufacturer's number is the only one worth judging against, and an open or dead-short reading condemns the coil whichever type it is.
- 4.Check continuity of the wiring from the PCM to the solenoid to find an open or short in the harness.
- 5.Verify the PCM is actually commanding and driving the circuit in live data before condemning the solenoid.
- 6.Confirm transmission fluid level and condition while you're in there — clean fluid is needed after any valve-body work anyway. If reaching the solenoid means dropping the pan, let the transmission cool first and put the vehicle on stands or a lift: the fluid is hot enough to scald straight after a drive, and this is work done with your head underneath the car.
Repair cost
$300 – $900 (torque converter clutch solenoid replacement)
This pair is torque converter clutch solenoid replacement. AutoZone's published band for a simple solenoid replacement is $300–$900, parts and labor. A connector or harness repair is not in this pair. RepairPal's transmission fluid change average, updated 3 September 2026, is $294–$356, with vehicle examples from about $162 to about $463. Fresh fluid is part of a pan-off solenoid job. It is not, by itself, a repair for an open or shorted circuit.
Estimate your repair
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DIY vs shop
Leave this one to a qualified shop. The barrier here is internal hydraulic and mechanical work, fluid handling at temperature, and an adaptive relearn afterwards without which a correct repair still shifts badly. DIY attempts often produce a more expensive problem than the original code.