P0742 on Chevrolet: How to Diagnose & Fix
Torque Converter Clutch Circuit Stuck On
13 Chevrolet models · 14 documented issues · 7 critical · $150-$4,500 repair
P0742 on Chevrolet by model: symptoms, diagnosis and fix
Both the 8-speed and 10-speed automatic transmissions can develop a shudder during light acceleration. This torque converter clutch issue is widespread across GM trucks. Multiple TSBs have been issued addressing this concern.
Common Symptoms
- Shudder during light acceleration
- Vibration at 25-50 mph
- Harsh shifts
- Hesitation when accelerating
- Shudder goes away under heavy throttle
How to Fix
Perform transmission fluid flush with GM-approved fluid and friction modifier additive. GM extended warranty coverage for some affected vehicles. Multiple fluid changes may be needed. Torque converter replacement in severe cases.
Sources for this issue (1)
The 8L45 8-speed automatic transmission can develop a shudder during light acceleration, typically between 25-50 mph. This is caused by torque converter clutch issues, similar to problems in other GM vehicles with this transmission family.
Common Symptoms
- Shudder during light acceleration
- Harsh or jerky shifts
- Vibration between 25-50 mph
- Transmission hesitation
- Clunk when shifting at low speeds
How to Fix
Perform transmission fluid flush with GM-approved fluid and friction modifier. Multiple fluid changes may help. GM has extended warranty coverage for some affected vehicles. In severe cases, torque converter replacement may be needed.
Sources for this issue (1)
The 8L90 and 8L45 8-speed automatic transmissions experience torque converter clutch shudder, causing vibration and shaking during gear changes. The issue is caused by the lock-up clutch slipping and chattering. This defect has been the subject of class action lawsuits against GM.
Common Symptoms
- Shuddering or shaking between 25-80 mph during gear shifts
- Vibration under light acceleration at 1000-1500 RPM
- Feeling like driving over rumble strips at highway speeds
- Sudden lurching or jerking during acceleration
How to Fix
Transmission fluid flush with updated Mobil 1 Synthetic LV ATF HP fluid. Torque converter replacement (may not permanently fix issue). TCM software reflash/update. Complete transmission replacement in severe cases.
Sources for this issue (1)
Transmission shuddering is common in Equinox models, typically caused by torque converter clutch issues or depleted transmission fluid additives. The shudder is most noticeable during light acceleration between 25-50 mph as the transmission shifts through 3rd-5th gears.
Common Symptoms
- Vibration or shudder during light acceleration
- Shaking between 25-50 mph
- Rough shifting between gears
- Transmission slipping sensation
- Check engine light with transmission codes
How to Fix
Transmission fluid flush and fill (3x flush procedure). Add transmission shudder fix additive (early intervention). Torque converter replacement. Complete transmission rebuild or replacement if severe.
Sources for this issue (1)
Express 2500 and 3500 vans built through roughly 2009 use the 4L80E. It is a genuinely strong unit, but the torque converter lockup clutch is its recognized failure point on high-mileage commercial vans. As the TCC lining wears, the transmission raises line pressure to compensate, so the first thing an owner notices is not slipping but hard, banging shifts - a symptom that gets misread as a valve body or solenoid problem. Shudder at lockup speeds, a bucking sensation around 45-55 mph and eventually a stall-on-stop follow. Related, heat and vibration kill the 2-3 shift solenoid, and GM bulletins for these vans document harsh shifts, a delayed 2-3 shift and slipping in third with solenoid replacement as the remedy. A separate quirk owners report on Express vans specifically is transmission fluid pushing out of the vent tube when the unit gets hot and the fluid expands, which then reads as a leak. Realistic service life is 120,000-180,000 miles; converters on 200,000-plus mile vans should be assumed suspect.
Common Symptoms
- Hard or banging upshifts
- Shudder or bucking at highway lockup speeds
- Engine stalls when coming to a stop
- Delayed 2-3 shift or slipping in third
- Transmission fluid found around the vent tube after hot operation
How to Fix
Scan for TCC codes and check line pressure before tearing into the valve body - rising pressure with hard shifts points at the converter clutch, not the solenoids. Repairing the lockup clutch requires removing the transmission, so it is done as a converter replacement paired with a rebuild if mileage warrants, plus a thorough cooler and line flush to clear the friction material. If the complaint is only a harsh or delayed 2-3 shift, replace the 2-3 shift solenoid per the GM bulletin first. For the vent-tube discharge, confirm fluid level is correct at operating temperature and add an auxiliary cooler rather than overfilling. No recall applies.
Sources for this issue (3)
- 4l80e of the Express Van Variety Questions - Grassroots Motorsports forumforum
- 4l80E shifting issue - Chevrolet Forum, Express/Savana G-Series Vans sectionforum
- Chevy Express 2500/3500 transmission problems and TSB summary (harsh shifts, delayed 2-3, slipping in third; 2-3 shift solenoid remedy)article
The first-generation Cruze with the 6T40 automatic transmission develops a shudder during torque converter lockup in the 25-45 mph range. The torque converter clutch friction material wears and generates debris that contaminates the fluid, worsening the shudder over time in a vicious cycle. The shudder feels like driving over a textured road surface and is most noticeable during gentle acceleration. The 6T40 in the Cruze sees more stress than in larger vehicles because the 1.4T engine produces torque at low RPM, keeping the converter locked more often.
Common Symptoms
- Vibration or shudder at 25-45 mph
- Shudder under light throttle application
- Rumble strip feeling during gentle acceleration
- Shudder disappears under heavy throttle
- Harsh or rough shifts between gears
How to Fix
Perform a complete transmission fluid exchange (not just a drain and fill) using ACDelco DEXRON VI ATF. Three drain-and-fill cycles with 500 miles of driving between each gives the best results. If the shudder persists after fresh fluid, the torque converter needs replacement ($800-$1,500 including labor). A TCM software update at the dealer can modify lockup behavior to reduce shudder. Change the 6T40 fluid every 30,000 miles to prevent the issue from developing.
Sources for this issue (1)
P0742 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0742 mean on a Chevrolet?
P0742 stands for "Torque Converter Clutch Circuit Stuck On." P0742 means the torque converter clutch (TCC) circuit is stuck on, meaning the lockup clutch that mechanically links the engine to the transmission stays engaged when it should release. The computer commands the clutch on and off, and when it detects the converter clutch remaining applied, it sets this code. The classic symptom is the engine stalling when coming to a stop, similar to driving a manual without pushing the clutch in, along with possible harsh shifts or poor fuel economy. It points to a hydraulic or solenoid problem inside the transmission rather than the engine. On Chevrolet it is documented across 13 models: Silverado 1500, Colorado, Camaro, Equinox, Express, Cruze, Corvette, Suburban, Impala, Tahoe, C/K 1500, Lumina, Malibu.
What are the most common causes of P0742?
The most common causes of P0742 are: Stuck or failed torque converter clutch solenoid, Stuck valve in the valve body (TCC apply valve), Contaminated or degraded transmission fluid, Internal transmission hydraulic leak holding the clutch on, Wiring or connector fault to the TCC solenoid, Faulty torque converter, Dirty or clogged transmission filter. The specific cause varies by vehicle.
How much does it cost to fix P0742 on a Chevrolet?
Published repair estimates on Chevrolet range from $150 to $4,500 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
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View P0742 across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.