The transmission selects first gear, but the observed behaviour does not match what the controller expects. A P0731 entry can sit beside slipping, harsh engagement or a warning on the dashboard. The repair enquiry needs to describe that behaviour as carefully as the code.
What the reference supports
Ross-Tech lists P0731 / 17115 as an incorrect first-gear ratio. Its possible causes span wiring and connections, gear-position sensing, solenoids and mechanical failure. Read the P0731 entry. These are different diagnostic routes; the code alone does not select one of them.
The vehicle and transmission identification are essential. A conventional automatic, dual-clutch gearbox and other transmission designs should not be treated as interchangeable because the dashboard symptom sounds similar.
Describe the engagement, not just the warning
Tell the garage whether the fault occurs from a standstill, during a downshift or only when warm. Record whether reverse and other forward gears remain available. Include recent fluid, gearbox, clutch, valve-body and software work without assuming any one repair caused the problem.
Garages should preserve the full scan and relevant recorded input/output-speed information. Keep the conditions and the source of each value with the report. Do not repeatedly provoke slipping or loss of drive to obtain a better recording.
Where AXION fits
We can discuss transmission-electronics assessment when the evidence points towards that route. Mechanical and hydraulic findings may be needed before a removed TCU can answer the repair question. Send a TCU enquiry before dispatching parts.
For a DSG that unexpectedly disengages a selected gear, also see our P2711 guide. It describes a different fault finding and should not be used as a substitute for the exact report.
Reviewed September 2026. Use the complete manufacturer-specific fault description and vehicle repair information.