First gear slipping.
P0731 — also written PO731, P 0731, 0731 — is the OBD-II code for gear 1 incorrect ratio. Same code, same fix: this page covers every spelling of it.
Your gearbox is 'slipping' in first gear; the computer sees the engine spinning fast but the wheels aren't keeping up. Common on high-mileage BMW 3 Series (ZF boxes) and older Vauxhall Insignias.
P0731 is a transmission fault code, typically costing £250–£2500 to put right in a UK garage.
What P0731 actually feels like to drive
- The car revs up like it's in neutral when pulling away from traffic lights, then 'bangs' into gear.
- Limp mode (home safe) kicks in, usually locking the car in 3rd gear to protect the box.
- Feels like you've been rear-ended when the car finally finds first gear.
- 'Transmission Service Required' message on the dash during cold starts.
- Struggling to climb steep driveways or hills from a standstill.
What causes P0731?
- Worn clutch pack
- Solenoid fault
UK vehicles that throw P0731 most often
- Vauxhall Insignia 2.0 CDTi (AF40 Transmission) 2008-2015
- BMW 3 Series 320d (ZF 6HP/8HP) 2006-2016
- Ford Focus/Mondeo 2.0 TDCi (Powershift DCT450) 2010-2015
- Volvo V70/XC70 2.4 D5 (Aisin Warner) 2007-2014
- Volkswagen Golf/Passat 2.0 TDI (DSG DQ250) 2005-2012
How P0731 is fixed
- Solenoid replacement
- Rebuild
The P0731 misdiagnosis that wastes money
I see folks panic and immediately buy a second-hand gearbox from a breaker's yard for £400, only to find the 'new' one has the same P0731 fault or worse. Others throw a cheap set of solenoids off eBay at it, which usually leak or have the wrong resistance. Nine times out of ten on the older Aisin boxes found in Volvos and Vauxhalls, it’s actually internal seal wear or a cracked piston, not the electronics. You're wasting your time swapping sensors if the internal clutch packs can't hold hydraulic pressure.
What a UK garage should charge for P0731
A basic diagnostic and fluid level check will run you £60-£90. If it's just a solenoid block (like on the VW DSG), you're looking at £350-£600 for parts plus £200 labour. However, if the clutch packs are burnt out, a proper UK specialist rebuild starts at £1,800 and can easily hit £2,500 including a new torque converter and genuine ZF or Febi fluid. A main dealer will simply tell you 'new gearbox required' and hand you a bill for £5,000+.
P0731 repair cost in the UK
Most P0731 repairs land between £250–£2500 including parts and labour. The spread is wide because the cheap fix (a sensor, a hose, a leak) and the expensive fix (a major component) throw the same code — which is why a proper diagnosis before parts are bought saves the most money.
Bob's tip on P0731
Before you let a garage quote you £2k for a rebuild, ask them to perform a 'Stall Test' and check the colour and smell of the ATF (Automatic Transmission Fluid). If it smells like burnt toast and looks like black coffee, the clutches are toast. Also, insist they check for software updates; on the Ford Powershift boxes, sometimes a TCM recalibration can mask ratio issues temporarily, but if the 'Incorrect Ratio' persists, it's mechanical. If they don't know what a 'live data pressure test' is, take your car elsewhere.
Can you drive with P0731?
Book in.
Urgency: high.