Yamaha PW error 34: Torque sensor voltage too high while riding
The motor controller has detected an abnormally high constant voltage from the torque sensor while you were pedalling under load. Because the reading is outside the expected range, the drive unit shuts motor assist down to protect the system. On most PW models the display shows the code, the assist lamp goes out, and walk assist is also disabled until the fault is cleared.
| 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 | A dealer torque sensor reference voltage adjustment typically runs €40 to €80 in labour; a replacement torque sensor adds roughly €90 to €180 for the part, and a full controller assembly €220 to €400 plus the same labour. |
Likely causes
- Faulty or failing torque sensor (most common) producing an out-of-range output voltage
- Damaged, chafed or pinched wiring harness between the torque sensor and the controller
- Corroded or unseated connector at the crank-based torque sensor or at the controller
- Water or contamination inside the torque sensor housing after washing or wet-weather riding
- Internal controller fault misreading a healthy sensor signal
How to fix Yamaha PW error 34
- Stop riding and switch the system off; do not keep using the bike with assist cut out.
- Inspect the crank-area torque sensor connector for moisture, dirt or corrosion and unplug-replug it if accessible.
- Trace the visible harness from the sensor into the frame for chafing, pinching or signs of impact damage.
- Dry any damp connectors with compressed air or a hair dryer on low heat, then leave the bike powered off for 30 minutes.
- Perform a full power cycle: remove the battery, wait two minutes, refit and switch on to see if the code clears.
- If the code returns, the bike must go to an authorised Yamaha or Giant dealer for a torque sensor reference voltage adjustment with the diagnostic tool, and replacement of the sensor or controller assembly if the adjustment does not bring the voltage back into spec.
Warranty: A genuine torque sensor or controller failure inside the usual two-year warranty period is normally covered, while damage caused by water ingress, crashes or aftermarket electrical work is treated as wear and excluded.
Typical cost: A dealer torque sensor reference voltage adjustment typically runs €40 to €80 in labour; a replacement torque sensor adds roughly €90 to €180 for the part, and a full controller assembly €220 to €400 plus the same labour.
Frequently asked
Can I reset yamaha error 34?
Power cycling the bike (battery out for two minutes, then back in) will clear the display if the fault was transient, but if the sensor is genuinely out of spec the code returns on the first pedal stroke. Only the dealer diagnostic tool can perform the reference voltage reset that this code actually needs.
Is it safe to keep riding with error 34?
No. Motor assist is shut off by the controller, so you are riding an unpowered heavy bike, and the underlying sensor fault can mask itself as intermittent loss of power. Walk the bike or transport it to a dealer instead.
How much will the repair cost and is it under warranty?
Plan on €130 to €280 for a sensor replacement including labour, or €260 to €480 if the controller is involved. Bikes under two years old with no crash or water damage history are usually covered by the manufacturer warranty.
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.