Yamaha PW error 73: Internal battery system fault
The battery management system has flagged an internal fault that affects the pack's own electronics rather than the motor or display. The drive unit typically cuts motor assist as a protective response, leaving the bike riding as an unpowered bicycle with the display and lights still drawing from the main pack where the layout allows it. The capacity indicator on the display may flash, freeze, or read a wrong percentage because the cell monitoring circuit is not reporting normally. Continued use risks deepening any cell imbalance or stressing the BMS further.
| 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 | Dealer bench diagnostics typically run €60 to €120, a complete replacement battery pack ranges from €500 to €900 depending on capacity and frame, and a specialist cell or BMS board repair on an existing pack sits between €180 and €450. |
Likely causes
- Water ingress into the battery housing through damaged or compressed rubber seals
- Loose, oxidised or bent contact pins between the battery and frame harness
- Cell imbalance from a single aged, swollen or damaged 18650 or 21700 cell inside the pack
- BMS firmware corruption after a deep discharge below the cut-off voltage
- Impact damage to the pack casing from a crash, drop or transport accident
- Manufacturing defect in the cell monitoring or balancing board
How to fix Yamaha PW error 73
- Stop riding, switch the system off and remove the key to prevent further stress on the cells.
- Take the battery off the frame and visually inspect the contact rail for dirt, moisture, burn marks or bent pins.
- Clean the contacts with isopropyl alcohol and a lint-free cloth, then refit the battery and make sure it clicks into the mount.
- Inspect the battery housing, mounting rails and rubber seal lip for cracks, deformation or water staining.
- Reinsert the battery, switch the bike on and watch the display for at least one full minute to see whether the code clears.
- If the code returns, the pack needs bench diagnostics with a Yamaha or Giant compatible service tool that the owner does not have.
- Have the battery pack inspected by a dealer; refer to the battery service manual for the approved test and replacement procedure.
Warranty: A genuine internal battery or BMS fault within the two-year statutory warranty period is normally replaced at no cost, while water ingress, crash damage, modifications, or a pack left fully discharged for weeks are treated as misuse and excluded.
Typical cost: Dealer bench diagnostics typically run €60 to €120, a complete replacement battery pack ranges from €500 to €900 depending on capacity and frame, and a specialist cell or BMS board repair on an existing pack sits between €180 and €450.
Frequently asked
Can I reset Yamaha error 73?
Switch the system off, remove the battery for about 60 seconds, then refit it firmly and power the bike back on. If the code reappears within one minute the fault is still active and cannot be cleared by the rider.
Is it safe to keep riding with error 73?
No. Motor assist will cut out without warning and the pack's own electronics are reporting a real internal fault, so pedalling home unpowered is the limit of what is reasonable. Pushing on risks deeper cell damage and a more expensive repair.
Will the repair be covered under warranty and what will it cost?
If the bike is under two years old and there is no visible water ingress, impact damage or tampering, Yamaha or Giant usually replaces the battery or BMS free of charge, although diagnostic labour is sometimes billed. Out of warranty a dealer replacement pack typically runs €500 to €900 including fitting.
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.