Yamaha PW error E42: Light / accessory circuit error
Yamaha PW series (PW-X3, PW-X2, PW-X, PW-ST, PW-TE, PW-SE, PW-CE) and Giant/Liv SyncDriveFix at homeSafe to keep riding
E42 points at the lighting or accessory output of the drive unit: a short circuit, overload or a broken wire on the light circuit. The motor keeps working but the lights do not, and the code stays until the wiring fault is removed. Also shown on Giant/Liv (SyncDrive) bikes, sometimes with a leading zero (E01) or as 'Er' followed by the number on older Yamaha displays.
Likely causes
- Damaged front or rear light cable
- Aftermarket light drawing too much current
- Water in a light connector
- Blown light unit
How to fix Yamaha PW error E42
- Disconnect the front and rear lights one at a time and power-cycle to find the faulty one
- Inspect light cables for chafing where they enter the frame or mudguard
- Dry the connectors
- Replace the faulty light or cable; dealer if the drive unit output itself is dead
Go to a dealer if: Dealer only if the lights and cables are proven good and the drive unit's light output still faults.
Warranty: A shorted aftermarket light is not warranty; a failed original light or drive unit output is.
Typical cost: Usually free / DIY; a light or cable is cheap.
Warranty: A shorted aftermarket light is not warranty; a failed original light or drive unit output is.
Typical cost: Usually free / DIY; a light or cable is cheap.
Still stuck? Take a photo of the display and show it to a local e-bike workshop. Bring the bike's system name (e.g. Bosch Performance Line CX) and the exact code; that saves diagnostic time and money.
Frequently asked
Can I reset E42 myself?
Yes, remove the short and power-cycle.
Can I keep riding with E42?
Yes, the motor is unaffected; ride in daylight until the lights are fixed.
Is E42 covered by warranty?
Only for original components.
Related Yamaha PW codes
Not an official Yamaha PW document. Compiled from workshop experience and public service information; details can differ per system version and bike brand.