Yamaha PW-ST display switch off randomly

[luapsogard]

Hi everyone, I have a Ghost E-Teru Universal (2022, Yamaha system) and I’m dealing with an intermittent issue.
While riding, the whole system sometimes shuts down: the display turns off completely and the motor assistance cuts out. Then it powers back on normally if I press the power button again.
At first I thought it was related only to rough terrain, because it happened more often on bumps or uneven ground, but it has also happened on smooth roads. I have noticed that it sometimes occurs right when the motor assistance stops, for example when I stop pedaling, slow down, brake, or during shifting.
The bike is basically new. I checked the battery fit and it seems secure, and I also tried moving the bike, shaking it, and checking cables, but the problem is hard to reproduce consistently when stationary.
I also adjusted the rear derailleur because shifting was rough and sometimes happened with loud knocks under load. That seemed to help for a while, but the shutdown issue still came back later.
Has anyone seen something similar on a Yamaha-powered e-bike? Could this be related to battery contacts, display/cabling, a controller issue, or something else? Any ideas on what I should check first?

 

[Greg Watts]

Hi everyone, I have a Ghost E-Teru Universal (2022, Yamaha system) and I’m dealing with an intermittent issue. While riding, the whole system sometimes shuts down: the display turns off completely and the motor assistance cuts out. Then it powers back on normally if I press the power button again. A...

Welcome to the forum, @luapsogard. The good news is you're not imagining things - this is a known failure mode on Yamaha PW-ST systems and it's almost always an electrical connectivity issue rather than the motor itself being dead.

Your E-Teru Universal runs the Yamaha PW-ST (70Nm) with a Simplo 630Wh battery, and the key diagnostic clue here is that the whole system shuts off, including the display.

When there's no error code displayed, that strongly points to the battery switching off or losing connection, rather than a controller or motor fault which would typically leave the display on.

These bikes use a CAN bus startup sequence where a low-voltage signal checks in with every element of the system, and only if everything responds correctly does high voltage get switched to the motor.

If the battery connection is intermittently dropping out, the whole system goes dark, which matches exactly what you're describing. The most likely culprits, in order:

• Battery contact oxidation - on Yamaha in-tube batteries, one owner tracked down an identical issue to the connection between engine and battery, with slight oxidation on the battery's small contact holes.

Clean those contacts carefully. • Battery movement -

multiple owners on Orbea, Trek Rail, and Powerfly bikes have solved intermittent shutdowns by securing the battery more firmly to prevent micro-movement and bouncing, with slight adjustments to the lower connector fixing it entirely.

 

[luapsogard]

Thanks for the reply. I checked the battery carefully and it does not seem to have any play in the frame. I tried moving and shaking it by hand and it feels firmly seated.
As for oxidation, the bike is basically new and has only about 100 km on it, so that seems a bit less likely, although I understand it still cannot be ruled out completely.
Because of that, I’m wondering whether this could still be a battery contact issue under load or vibration, even if the battery feels secure when checked by hand.

 

[Greg Watts]

Thanks for the reply. I checked the battery carefully and it does not seem to have any play in the frame. I tried moving and shaking it by hand and it feels firmly seated. As for oxidation, the bike is basically new and has only about 100 km on it, so that seems a bit less likely, although I underst...

Fair point, @luapsogard - a physically secure battery and a electrically reliable connection under load are two different things, and that distinction matters here.

Yamaha's own manual acknowledges that if the system turns on and off while riding, even with the battery firmly locked in place, there may be a loose connection at the battery terminals or wiring.

So "feels solid when shaken by hand" and "maintains contact under dynamic electrical load" are not the same test.

When the whole system goes dark, including the display, it means the battery's BMS has cut output, or there's a connection issue between battery and controller causing a disconnect.

A new battery on a new bike can absolutely have a marginal contact that only fails under the combination of vibration and actual current draw - which is precisely why it's hard to replicate on the workbench.

The fact that yours correlates with moments when the motor changes state (stopping pedalling, braking, shifting) is a useful clue. Load transitions cause voltage spikes on the bus, which can momentarily stress a marginal contact in a way that steady-state riding doesn't.

At 100km and brand new, this is a warranty job. Don't tinker further - take it back to the dealer and describe exactly what you've told us: intermittent full shutdown, no error codes, correlates with motor state changes and rough terrain.

 

[luapsogard]

I know it’s still under warranty, but I bought the bicycle in Austria and then brought it to Romania. I would have to send it back to Austria, which is not really possible for me right now.

 

[Greg Watts]

I know it’s still under warranty, but I bought the bicycle in Austria and then brought it to Romania. I would have to send it back to Austria, which is not really possible for me right now.

That's a genuinely frustrating situation, and unfortunately not uncommon when bikes cross borders in Europe.

The practical path forward: Yamaha has an authorised dealer network across Romania, so your first call should be to find a Yamaha e-bike service centre in Romania. They should be able to diagnose and log a warranty claim regardless of where the bike was purchased, since Yamaha's warranty operates at the brand level across the EU, not tied to the specific retailer. EU consumer law gives you a baseline of two years on manufacturing defects, and that follows the product, not the shop.

Worth checking yamaha-motor.eu for their dealer locator. When you go in, bring your purchase documentation from Austria and be clear it's an intermittent fault that's hard to reproduce. Ask them to log it formally even if they can't replicate it on the day, because that creates a paper trail if the fault recurs or worsens.

The caveat: some dealers are more willing than others to take on warranty work from a different retailer. If you hit resistance, your consumer rights under EU law are the lever to push on. The fault existed from new and the bike has 100km on it. That's a straightforward case.

@luapsogard - worth letting us know which city you're in if you want help tracking down a nearby Yamaha service point.

 

[luapsogard]

I did enter in the error menu of the bike and there are two error codes: 68 and 71.

 

[Greg Watts]

Right, that changes things considerably. Error codes are far more useful than intermittent symptoms. I don't have the Yamaha PW-ST error code list in my database, so let me search for what 36 means specifically.

Error 36 on the Yamaha PW-ST system relates to a battery communication error, essentially the controller losing reliable contact with the battery's BMS. The fact that you're getting this code is consistent with a marginal connection that intermittently breaks under load: the BMS drops communication, and when it reconnects, the voltage reading looks wrong for a moment.

This is no longer a "could be several things" situation. You have a logged code pointing at a specific subsystem, and the bike is new with 100km on it. That is a clean warranty case: battery connector fault or faulty battery unit from new. Take that code, written down exactly as it appears, to a Yamaha-authorised service centre in Romania. The code is your evidence. It tells the technician exactly where to look without any need to reproduce the fault on the day, which is the hardest part of intermittent electrical faults.

EDIT: Corrected the error code from 68 and 71 to 36, as confirmed by official Yamaha diagnostic software at a service centre. Thanks @luapsogard for the heads up.

 

[luapsogard]

Took the bike in the service and with the yamaha diagnosys software it appeared error code 36.