4L60E P0742 TCC Stuck On: Causes and Fix

P0742 means TCC is engaging and won't release. Engine wants to stall at stops. Here's what causes it and how to fix.

What P0742 means

• Torque Converter Clutch stuck applied
• TCM commanded release, but TCC stays engaged
• Engine load doesn't decouple at idle
• Read our 4L60E common failure codes

Symptoms

• Engine wants to stall at stops
• Rough idle approaching red lights
• Sometimes won't shift out of TCC mode
• Code P0742 set

Common causes

1. TCC solenoid stuck open

• Most common
• Solenoid mechanically stuck on
• Replace solenoid
• Read our 4L60E TCC solenoid replacement

2. TCC apply piston seal failure

• Apply piston seals damaged
• Can't release pressure
• Requires rebuild or piston replacement
• Read our 4L60E TCC apply piston

3. Valve body checkball position

• Wrong checkball position after rebuild
• Read our transmission rebuild mistakes

4. Wiring issue

• Short keeping solenoid energized
• Less common but possible

Diagnosis

• Pull all codes (look for companion codes)
• Test TCC solenoid resistance
• Pan inspection
• Read our transmission pan inspection

Quick test

• Disconnect TCC solenoid electrical at trans
• If problem stops: solenoid stuck mechanically OR wiring issue
• If problem persists: apply piston / valve body issue

Repair cost

Solenoid only:

• Solenoid: $80-$200
• Pan drop fluid/filter: $80-$150
• DIY install: 4-6 hours
• Total: $200-$400

Apply piston rebuild:

• Full rebuild needed
• $1,500-$3,500
• Read our best 4L60E rebuild kit

Pair with HD upgrades

• HD TCC apply piston during rebuild
• Updated TCC PWM solenoid
• Read our 4L60E TCC apply piston

Don't ignore

• Stalling at stops = safety hazard
• Engine wear accelerated
• Read our transmission warning signs

Need 4L60E TCC parts? Shop our 4L60E catalog. TCC solenoids, apply pistons, rebuild kits. Free shipping over $70.

Related:

• 4L60E TCC solenoid replacement
• 4L60E TCC apply piston
• 4L60E common failure codes