Bosch error 0x550351: Rear light defective or not detected
The control unit cannot communicate with the rear light, sees a short or open circuit on the light line, or detects that the lamp is drawing too much or too little current. As a result the tail light is switched off and you have no brake light or running light at the rear. The motor assist itself is not affected by this fault, so the bike will still ride normally.
| Drive system | Bosch eBike (DiagnosticTool / eBike Flow hex code) |
| Severity | Fix at home |
| Keep riding? | Safe to keep riding |
| Typical cost | A replacement Bosch rear light typically runs 25 to 60 EUR, a full rear light with rack and plug assembly 60 to 120 EUR, and dealer labour for harness diagnosis is usually 40 to 80 EUR on top. |
Likely causes
- Loose or corroded rear light connector at the seatpost or rack mount
- Damaged cable between the main harness and the rear light, often chafed at the rack hinge
- Tail light itself failed, most often water ingress or a burnt LED board
- Plug not fully seated after wheel or rack removal for a puncture repair
- Aftermarket light with wrong wattage causing an overload report
- Cracked or pinched cable inside a folding seatpost or suspension seatpost
How to fix Bosch error 0x550351
- Switch the system off, remove the key or shut down via the display, and wait 30 seconds before powering on again to see if the code clears.
- Inspect the rear light connector: unplug it, check the pins for green corrosion or bent contacts, then refit firmly until it clicks.
- Trace the cable from the rear light to the main harness and look for chafing, pinched sections or a broken wire, especially where the cable enters the seatpost or passes the rack.
- Test with a known good Bosch-compatible rear light if one is available, swapping in a spare to confirm whether the lamp itself is the fault.
- Refit or replace the rear light and its plug as the official remedy states.
- Take the bike to a Bosch dealer if the code persists after the light and cable check, so the harness and control unit output can be measured with DiagnosticTool.
Warranty: A genuine rear light or wiring fault inside the two-year Bosch warranty period is normally covered as a component defect, whereas corrosion from water ingress, crash damage and worn connectors are treated as wear and not covered.
Typical cost: A replacement Bosch rear light typically runs 25 to 60 EUR, a full rear light with rack and plug assembly 60 to 120 EUR, and dealer labour for harness diagnosis is usually 40 to 80 EUR on top.
Frequently asked
Can I reset bosch error 0x550351?
There is no rider-level reset for this code. A power cycle will clear it if the fault has gone away, but if the rear light circuit is still open or shorted the code returns immediately on the next ignition.
Is it safe to keep riding with 0x550351?
Yes, the motor and brakes are unaffected, so the bike rides normally. You do lose the rear light and brake light, which is a legal and visibility problem after dark, so ride only in daylight and fit lights before night use.
How much does the repair cost and is it under warranty?
Expect 25 to 120 EUR for the part depending on whether you need just the lamp or the full rack light assembly, plus 40 to 80 EUR dealer labour if a harness fault is found. Inside the two-year warranty period a genuine Bosch rear light failure is normally replaced free of charge.
Related Bosch codes
Manuals and video
- Bosch eBike Help Center: official error-code index
- Bosch eBike downloads: quick start guides and battery guide
- Bosch eBike dealer search (DiagnosticTool readout)
Official source: www.ridewill.com
Not an official Bosch document. Compiled from workshop experience and public service information; details can differ per system version and bike brand.