King-Meter error 09: Motor phase line fault detected
The controller has detected a problem on one of the three phase wires that drive the motor. Assist switches off immediately, the speed reading drops to zero, and walk assist is disabled. The display holds the error until power is cycled, even if the fault clears momentarily.
| Drive system | King-Meter K5242 / KM5S LCD display |
| Severity | Dealer needed |
| Keep riding? | Do not keep riding |
| Typical cost | Phase cable and connector repair runs €20–80, a replacement controller €80–200, and a complete motor rebuild or swap €250–450 depending on the model. |
Likely causes
- Loose or unseated motor phase connector at the controller
- Chafed, pinched, or cut phase cable from frame flex or cable routing
- Water or corrosion inside the phase connector
- Burnt controller output stage (MOSFET failure)
- Internal short in the motor winding
- Poor aftermarket repair or replaced connector with wrong spec
How to fix King-Meter error 09
- Switch off the system and remove the battery before touching any wiring.
- Trace the phase cable from the motor housing to the controller and inspect the full length for cuts, chafe, or pinch points.
- Unplug the phase connector at the controller, check the pins for corrosion or bent contacts, and re-seat it firmly.
- Clean any green or white corrosion with electrical contact cleaner and dry fully before reconnecting.
- Inspect the controller housing for discolouration, melted plastic, or a burnt smell.
- Reinstall the battery, power on, and check whether the error clears during a short static test.
- Take the bike to a dealer if the fault persists: internal motor winding or controller output stage diagnosis is required with a meter and bench rig.
Warranty: Motor and controller are normally covered against manufacturing defects for two years from purchase, while water ingress, crash damage, and corroded connectors from poor maintenance are excluded.
Typical cost: Phase cable and connector repair runs €20–80, a replacement controller €80–200, and a complete motor rebuild or swap €250–450 depending on the model.
Frequently asked
Can I reset king-meter error 09?
Power cycling clears the code from the display, but it returns as soon as the controller sees the phase fault again. There is no hidden reset sequence; the underlying wiring or component must be repaired.
Is it safe to keep riding with error 09?
No. Motor assist cuts out and the bike behaves like an unpowered bicycle, so on hills or in traffic it becomes hard to handle. Continuing to ride can also drive more current into a shorted phase and damage the controller.
What does the repair typically cost, and is it under warranty?
If the bike is under two years old and the fault is a manufacturing defect, the motor or controller is usually replaced at no cost. Outside warranty, expect €20–80 for cable work, €80–200 for a controller, and €250–450 for a motor replacement.
Related King-Meter codes
Official source: King-Meter K5242 LCD manual, appendix 1 Error Code Definition
Not an official King-Meter document. Compiled from workshop experience and public service information; details can differ per system version and bike brand.