P0742 — Torque Converter Clutch Circuit Stock On

powertrain (engine/transmission)

Is it safe to drive?

Drive with caution Drive only if the transmission still shifts predictably, and avoid highway speeds. Driving with slipping or limp mode accelerates internal wear — every kilometre can add to the final repair bill.

How to diagnose with an OBD scanner

Read the code and freeze frame Connect an OBD2 scanner, confirm P0742 is stored, and save the freeze frame data — it shows engine conditions when the fault was detected.
Check for companion codes and TSBs Related codes often reveal the real root cause. Also check manufacturer technical service bulletins (TSB) for your make and model — many P0xxx issues have factory fixes or software updates. Search by VIN on the manufacturer site or nhtsa.gov.
Inspect wiring and connectors Visually inspect the wiring harness and connectors related to the automatic transmission control for damage, corrosion, chafing or poor contact.
Subsystem check Check transmission fluid level and condition — dark, burnt fluid points to internal wear.
Subsystem check Read transmission-specific codes and live data (solenoid states, input/output speed) with a capable scanner.
Verify the repair Clear the code, complete a full drive cycle including the conditions from the freeze frame, and confirm P0742 does not return.

Approximate repair cost

Repair cost depends on which component actually failed. Typical scenarios for P0742 (parts and labor, USD, independent shop rates): Transmission fluid service: $150–$350; Replace a shift solenoid: $300–$800; Valve body repair or replacement: $700–$1,500; Transmission rebuild or replacement: $2,500–$5,500. Overall, fixing P0742 usually costs between $150 and $5,500. An accurate diagnosis before buying parts saves money — the most expensive scenario is rarely the first one to check.

Common questions

Is it safe to drive with P0742?

Drive only if the transmission still shifts predictably, and avoid highway speeds. Driving with slipping or limp mode accelerates internal wear — every kilometre can add to the final repair bill.

What are the symptoms of P0742?

Drivers most often notice: slipping between gears, Check Engine or transmission warning light on, transmission stuck in one gear (limp mode), harsh or delayed shifting.

How much does it cost to fix P0742?

Transmission fluid service — $150–$350; Replace a shift solenoid — $300–$800; Valve body repair or replacement — $700–$1,500; Transmission rebuild or replacement — $2,500–$5,500. Exact cost depends on the root cause, your vehicle and local labor rates — a proper diagnosis is the cheapest first step.

What does OBD2 code P0742 mean?

Torque Converter Clutch Circuit Stock On (P0742): a powertrain (engine/transmission) fault affecting the automatic transmission control. Short, gentle driving to a shop is usually possible. Most often caused by wiring or connector faults in the valve body harness, failed shift or pressure control solenoid, faulty transmission speed sensor.

Will P0742 clear itself?

Sometimes P0742 clears after a few drive cycles if the fault was intermittent — for example a loose connector or a tank of bad fuel. The underlying cause usually remains, so the code tends to return. Clear it once; if it comes back, diagnose rather than erase it repeatedly.

When your vehicle's computer detects a problem with the torque converter clutch control circuit, it logs trouble code P0742. This code specifically indicates that the circuit is stuck in the "on" position — meaning the torque converter clutch solenoid isn't cycling properly as it should during normal driving. The torque converter clutch is designed to lock up at cruising speed, which improves fuel efficiency and reduces heat. When the circuit stays engaged instead of releasing, it creates a continuous mechanical link between the engine and transmission that shouldn't always be there.

The transmission control module (TCM) or powertrain control module (PCM) continuously monitors the voltage and operation of the torque converter clutch solenoid circuit. P0742 triggers when the module sees that this circuit has been activated for longer than expected or shows electrical readings that don't match what the software expects. This causes the check engine light to illuminate and stores failure data so a technician can see exactly what was happening in the engine and transmission at the moment the fault occurred.

This is a powertrain-category code, meaning it affects both the engine and automatic transmission system. The stored freeze frame data is critical — it captures engine RPM, vehicle speed, transmission temperature, and load values when P0742 first set, giving you the best starting point for tracking down whether this is an electrical issue or something more serious inside the transmission.

Common Symptoms

Noticeable gear slipping or inconsistent gear engagement
Check Engine or transmission warning light illuminated on the dash
Transmission locked into a single gear (fail-safe or limp mode)
Harsh shifting or delayed gear changes
Vibrations or shuddering felt at highway speeds
In severe cases, complete loss of forward or reverse movement

What Causes P0742?

Failed or failing torque converter clutch solenoid
Damaged wiring or corroded connectors in the transmission harness
Faulty transmission input or output speed sensor
Worn or contaminated transmission valve body
Internal transmission wear including clutch packs or the torque converter itself
Failed TCM or PCM software issue

How to Diagnose P0742

Connect a quality OBD2 scanner and confirm P0742 is stored in the transmission or powertrain control module. Record the freeze frame data — this snapshot shows RPM, speed, temperature, and load when the fault occurred.
Pull all stored and pending codes from the TCM/PCM. Related transmission codes often point to the root cause rather than the symptom. Check manufacturer TSB databases and NHTSA for known issues affecting your specific make, model, and year — many P0742 cases have documented factory fixes or software updates.
Perform a thorough visual inspection of the transmission wiring harness and electrical connectors. Look for frayed wires, melted insulation, corrosion, bent pins, or loose connections that could interrupt the solenoid signal.
Check transmission fluid level and condition with the engine at operating temperature. Dark, burned-smelling, or foamy fluid indicates overheating or internal wear that could be contributing to the fault.
Use a transmission-capable scanner to read live solenoid operation data, input/output speed sensor values, and pressure readings. Compare these to factory specifications for your vehicle.
Clear the code and complete a full drive cycle that reproduces the freeze frame conditions. If P0742 returns, the fault is confirmed and requires physical repair rather than an intermittent electrical glitch.

Repair Options and Costs

Transmission fluid and filter service — $150–$350. In many cases, simply draining and replacing old fluid along with the filter resolves solenoid sticking caused by contaminated fluid.

Torque converter clutch solenoid replacement — $300–$800. The solenoid itself is often the direct cause of the circuit staying on. Labor involves dropping the transmission pan and accessing the valve body.

Valve body repair or replacement — $700–$1,500. If the solenoid is functional but the valve body passages are worn, clogged, or cracked, the entire valve body assembly may need repair by a specialist or full replacement.

Transmission rebuild or replacement — $2,500–$5,500. Internal failures including worn clutch packs, a failed torque converter, or extensive valve body damage require teardown repair or a complete transmission unit swap.

Total Cost Breakdown

Most P0742 repairs fall between $150 and $800 if addressed early through fluid service or solenoid replacement. Valve body work typically runs $700–$1,500, while a full transmission rebuild or replacement can reach $5,500. The wide range reflects how much disassembly is needed and whether the issue is electrical, mechanical, or both. An accurate diagnosis before purchasing parts prevents spending $1,500 on a valve body when the wiring harness simply needs a connector repair.

Can You Drive with P0742?

This fault carries a Caution severity rating. Short-distance driving on flat roads may be manageable if the transmission still shifts and no shuddering is present. However, continued operation with the torque converter clutch stuck on accelerates wear on internal transmission components and the converter itself. Highway speeds increase heat and stress significantly. If the vehicle enters limp mode or exhibits slipping or shuddering, have it towed rather than risk compounding the damage with every additional mile.