Powertrain, generic · Transmission
P0742 Torque Converter Clutch Circuit Stuck On
Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible
P0742 means the converter clutch stays applied although commanded off – there is almost no slip. GM's T43 flags −50 to +13 rpm for 1.5 s six times and the 6T70 −20 to +30 rpm for 2.5 s, both after one trip; Allison and Saab's Aisin AF40 after two trips, the AF40 also when the engine stalls without slip. Typical is the engine stalling when stopping or when selecting D or R, plus jerking at low speed. Note the different uses: Ford's P0742 is a short to ground in the clutch solenoid circuit (stuck on is P2758 there), and Saab's 9-3 of 2003 uses it for a mechanical lock-up fault.
Likely causes
Converter clutch control valve sticking in the applied position
Solenoid stuck open (or short to ground with low-side control)
Lock-up clutch seized in the converter
Wrong fluid level or contaminated fluid
Engine or turbine speed signal implausible
Symptoms
- Engine stalls when stopping or selecting D/R
- Jerking or bucking at low speed
- Check engine light or transmission warning
Repair estimate
DifficultyHardWorkshop job
Parts and labour€200–3,000
Time2–10 h
Typical range across vehicles; the real cost depends on what the testing finds.
Parts involved
torque converter clutch solenoidtorque convertertransmission valve bodytransmission control module
Related codes
References: gsi.ext.gm.com, saabwisonline.com, saabwisonline.com, gsi.ext.gm.com.