Husqvarna MC4 Shimano motor error code 299 — can it be reset?

[stephan.phaneuf]

My bike is a Husqvarna MC4.

I am getting error code 299 on the shimano motor system. Can this be resetted?

@Greg Watts

 

[Greg Watts]

Short answer: no, you can't reset it yourself. And I'm afraid that's not me being lazy — it's by design.

What E299 actually is

E299 is Shimano's anti-tamper flag. The EP8/EP801 firmware decided, rightly or wrongly, that something on the system looked like a derestriction attempt (a tuning dongle, a dodgy speed sensor reading, a wheel-size mismatch, electronic gearing miscalculating expected vs actual speed, etc.) and threw the tripwire. Once it's set, it's written to Non-Volatile Memory inside the drive unit.

Why disconnecting the battery won't save you

As @Astro66 has explained on here, NVM is exactly what it says on the tin — non-volatile. Pulling the battery for a weekend, a month, even a year won't clear it. The estimate floating around is 12+ months of full disconnection might wipe it, and by then you'd have lost the firmware too. Not a fix.

Only Shimano's internal service tool (not E-Tube, not the SM-PCE02 you can buy) can clear E299. Dealers don't have it. You don't have it. The bloke on YouTube doesn't have it.

What you're looking at

• Bike goes back to a Shimano-authorised service centre
• Motor typically gets replaced, not repaired — @Backflip has noted this is the standard outcome
• If the system thinks you tampered, warranty is likely void and you pay for the replacement motor
• If you genuinely didn't tamper, push hard for a goodwill claim — document everything

Before you send it in, sanity-check this

• Did you (or a previous owner) ever fit a SpeedBox, PearTune, MBIQ, BadAss, RedPad or Planet3? On EP801 those guarantee E295/E299 and flag the motor permanently
• Running electronic gearing (Di2/AXS) with an incorrect chainring or cassette config? The motor calculates expected speed from gear ratios — if reality doesn't match, it assumes derestriction
• Non-standard speed sensor magnet (e.g. swapped to Centerlock rotors without a proper magnet)? @Bndit found Galfer CL or Specialized CL lock magnets are the safe options

If none of those apply, you've got a leg to stand on with Shimano. If one does, brace yourself.

What bike is it on, and is there any tuning/dongle history you know of? That'll shape whether this is a warranty fight or a wallet event.

 

[Backflip]

My bike is a Husqvarna MC4.

I am getting error code 299 on the shimano motor system. Can this be resetted?

@Greg Watts

@Greg Watts already did bring things together in a very good way. Thanks Greg - you have done very well!

@stephan.phaneuf
Welcome to the forum!
So most probably you have used one of these "crappy dongles" (external electronic hardware box) Greg already have mentioned on your DU-EP801 based Husqvarna bike to speed up your bike instead of using a really error-free and hassle-free working and forever lasting tuning tool.
I had written many forum posts about this topic already.
I just wanted to mention that you never, ever should ignore the preceding 4 times E295 errors which finally will result in the fatal E299 error which will completely lock your drive unit and so makes the bike next to unuseable!
I know this is too late for you now and you have to send your bike or drive unit to a Shimano service centre.

However, for all other readers: Never, ever just ignore an E295 error on a Shimano STePS based bike (even if the bike will start again after a power on cycle) and check instantly what´s wrong, otherwise definitely the final fatal E299 will result and this will cause a lot of frustration then...

 

[Greg Watts]

@Greg Watts already did bring things together in a very good way. Thanks Greg - you have done very well! @stephan.phaneuf Welcome to the forum. So most probably you have used one of these "crappy dongles" (external electronic hardware box) Greg already have mentioned on your DU-EP801 based Husqv...

@Backflip - cheers, and well said on all counts. Good to have someone who actually knows the EP801's architecture inside out backing this up.

Good news for @stephan.phaneuf: the MC4 is confirmed as a DU-EP801-based bike - Husqvarna houses the EP801 in an upright position specifically to improve passive cooling, so everything we've said about the EP801's NVM flag behaviour applies directly to his situation. No ambiguity on the platform.

And @Backflip's point about E295 is the one I'd underline in red for anyone reading this thread later. The E295 → E299 escalation path is not a surprise - it's a four-strikes-and-you're-out system, and Shimano isn't subtle about it. As @MOG's post spells out from painful personal experience: "I had exactly the same experience... it is just a matter of when."

On the eMax-Tuning link @stephan.phaneuf dropped in - worth clarifying for the thread: that's eMax's product homepage, and it will not help with E299. eMax is a legitimate tuning tool for EP801/EP600 bikes on appropriate firmware, and @Backflip has covered its capabilities thoroughly elsewhere on the forum. But E299 is a motor-level lockout, not a firmware parameter - no tuning software of any flavour touches it. That fight is with Shimano directly, not a Windows app.