The transmission module divides input (turbine) speed by output speed and compares the result with the ratio of the commanded gear; a deviation means slip – a clutch or brake not holding, too little pressure – or a wrong gear. Thresholds: Ford more than 30 rpm off for 1.8 s three times (diesel 2023: over 20 % for 12 s), GM's 2006 tables and the Allison 1000 converter slip of 200–230 rpm for 2.25 s after one trip, Saab's Aisin boxes over 20 % twelve times without MIL. P0731 concerns first gear. A 2006 GM table uses a tighter 4 % limit here and caps output speed at 1260 rpm; Saab's 2002 9-5 flags 3 % with the brake released. With a one-way clutch in first, slip shows as slipping when pulling away. On GM manual transmissions it checks the gear position sensor instead.
Medium severity. Can I keep driving?Drive gently to a repair shop. If it slips, you hear clunks, or it loses its gears, do not keep driving.
Symptoms
- Slipping or flare in first gear, engine speed higher than expected
- Harsh or delayed shifts
- Limp mode (Aisin: second gear and reverse only), transmission warning
- Check engine light depending on manufacturer
Most likely causes
- Fluid level too low or fluid worn or contaminated
- Clutch or brake for first gear worn (linings, piston seal)
- Sticking shift or pressure valve, leaking valve body gasket, blocked passages
- GM manual transmissions only: gear position sensor faulty or not learned
What to check, in order
Start with the simplest. You can tick off each step.
Good to know
- Repair difficulty: hard
- It can trigger limp mode.
- It affects emissions.
What each character of P0731 means
- P: Powertrain: engine and transmission
- 0: Generic code: same on every make
- 7: Transmission
- 31: Specific fault in that system
Frequently asked questions
Can I keep driving with code P0731?
Drive gently to a repair shop. If it slips, you hear clunks, or it loses its gears, do not keep driving.
What causes code P0731?
The most common causes are: fluid level too low or fluid worn or contaminated; clutch or brake for first gear worn (linings, piston seal); sticking shift or pressure valve, leaking valve body gasket, blocked passages.
Related codes
- P0730Incorrect Gear Ratio
- P0732Gear 2 Incorrect Ratio
- P072CStuck in Gear 1
- P0751Shift Solenoid A Performance/Stuck Off
- P0716Input/Turbine Shaft Speed Sensor A Circuit Range/Performance
- P0721Output Shaft Speed Sensor Circuit Range/Performance
Sources
- saabwisonline.com: dtc p0731
- saabwisonline.com: p0731 00
- saabwisonline.com: p0731
- gsi.ext.gm.com: 2006trans7
Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.