Yamaha PW error 31: Torque sensor signal lost on Yamaha PW drive
The motor controller has lost the signal from the torque sensor in the bottom bracket, which measures how hard you pedal. As a result, motor assist switches off completely and the bike rides as an unpowered bicycle. A simple restart may clear it, otherwise the system stays in limp mode until the sensor or wiring is repaired.
| Drive system | Yamaha PW series (PW-X3, PW-S2, PW-ST, PWseries CE - also Giant SyncDrive) |
| Severity | Dealer needed |
| Keep riding? | Do not keep riding |
| Typical cost | Budget roughly €120 to €220 for a torque sensor replacement and €280 to €450 if the controller needs swapping, plus around €60 to €90 for diagnostic time and fitting at a Yamaha dealer. |
Likely causes
- Loose or corroded torque sensor connector at the bottom bracket
- Damaged wiring harness between the torque sensor and controller, often chafed against the frame or chainstay
- Water ingress into the bottom bracket area after washing or riding in heavy rain
- Internal failure of the torque sensor element itself
- Controller fault preventing it from reading the sensor signal correctly
- Impact damage to the crank or bottom bracket assembly after a crash
How to fix Yamaha PW error 31
- Switch the e-bike off using the display power button.
- Wait at least 10 seconds, then power on again and check whether the code clears on the next ride.
- If the code persists, remove the battery before any further inspection.
- Look at the wiring around the bottom bracket for obvious damage, kinks, crushed sections or green corrosion on the connector pins.
- Disconnect and reconnect the torque sensor plug at the bottom bracket to rule out a poor contact, then refit the battery and test.
- If the code returns immediately the fault is internal and the bike needs a dealer-level diagnosis.
- Book the bike in with an authorised Yamaha dealer to replace the torque sensor or controller assembly and run the system diagnostic.
Warranty: A genuine torque sensor or controller failure inside the two-year manufacturer warranty is normally covered, but crash damage, water ingress and corrosion from poor maintenance are treated as wear and excluded.
Typical cost: Budget roughly €120 to €220 for a torque sensor replacement and €280 to €450 if the controller needs swapping, plus around €60 to €90 for diagnostic time and fitting at a Yamaha dealer.
Frequently asked
Can I reset Yamaha error 31?
Yes, switch the display off, wait about ten seconds, then switch it back on. If the sensor signal returns to normal the code clears itself; if it reappears straight away the fault is real and needs repair.
Is it safe to keep riding with this error?
No. Motor assist cuts out completely so you are effectively riding an unpowered bike, and continuing to ride risks further damage to the wiring or sensor if the cause is a chafed cable.
How much does the repair cost and is it under warranty?
Expect €120 to €220 for a torque sensor and €280 to €450 for a controller, plus labour. Inside the two-year warranty a genuine component failure is usually covered, but water damage and crash damage are not.
Related Yamaha PW codes
Manuals and video
Official source: cdn2.yamaha-motor.eu
Not an official Yamaha PW document. Compiled from workshop experience and public service information; details can differ per system version and bike brand.