Fix the Bosch E-bike 503 Error and Speed Not Reading

[@MickAussieMoose]

Thanks Arleigh. I have previously had this problem. One extra tip on Tern (possibly Bosch) sensors is that the my first idea was that the magnet should align with the larger circular part at the back of the frame mounted sensor. This is however not correct. There is a line across the body of the sensor from top to bottom of the sensor (can be seen from the other side, looking through the spokes) that the magnet should align with.

[@louisemclennan223]

Thanks for such a clear and straightforward explanation - I was able to fix mine and have the speed registering again!

[@BikeShopGirl]

Glad it helped!

[@freysteinngjonsson3240]

Thanks. This fixed the problem but I had to take out the battery for 10-20 sec and replace it again. All went well.

[@guyfisher5791]

Thank you. Very clear video. Put some air in the tires of my Tern HSD P9 for the first time this morning. (I've only had it a month). I had to move the magnet to use the pump. Put it back on about 4cm too high on same spoke because I didn't know about the sensor. No 503 error reading, but the motor kept cutting in and out. I was able to coast down the hill to get my bus...

[@Gavin_Gbk]

I was getting the intermittent 503 error, but it usually appeared after riding 5 or 6 miles, then, if I turned the display on and off, and pressed a few buttons, it would get me going for a couple of more miles, but the 503 error reappeared. I moved the magnet, reset it with the line on the sensor, I even bought a pack of 10mm x 1mm magnets and stuck one of those on the spoke magnet to bring it closer to the sensor, but still the same. I had looked at the cable and I couldn't see any external damage, the cable then goes from the sensor and inside the motor casing, it was tightly coiled inside, and appeared to be trapped by one of the bolts holding a fixing plate. I freed up the cable and checked for damage but none was apparent. I then looked at the connector of the cable inside the motor casing, and although this appeared to look OK, I unplugged and reinserted the plug a couple of times, and then made sure it was fully inserted, (be careful if doing this as the 2 pins inside the socket are very delicate). I tested the bike by doing a 16 mile ride and everything seemed perfect, but the fault returned. Update 17th August 2023 - The fault has returned, I have now sent an email to Bosch about this problem, asking what is happening, and what can done about it, but Bosch has not replied to my email as of 23rd. August 2023. I have now purchased and replaced the actual speed sensor, and after doing a 25 mile ride yesterday, everything now seems OK, so if you have checked all the above, and are still having problems, replace the speed sensor, (others have also reported speed sensor problems). If I get any more problems, I will update this message, so you can assume that everything is still working OK if you don't see any further update.

[@jessesoneff3696]

Thanks for sharing! This sound like what I’m going throughout now too. Whats the process for replacing the speed sensor? Do I need to take apart the display monitor?

[@gavingillespie7266]

@@jessesoneff3696 On my bike, I did not have to touch the display at all as the cable from the speed sensor only goes to the motor in the crank housing, so about 10 inches, 25cm. I originally thought that the cable from the speed sensor went to the display, and I was going to have problems routing the cable through the frame, but when I took the cover off the motor housing I could clearly follow the cable from the sensor to the connector on the motor.

[@garyharty1902]

thanks Arleigh. I have moved my magnet to the opposite side of the wheel from the valve stem on the theory that the wheel would be better balanced with the weight of the magnet off setting the weight of the valve stem. In the olden days, we use to adjust wheel bearings to the point where a wheel could rotate back and forth like a pendulum just from the extra weight of the valve stem. I've always wondered why the magnet is right next to the valve stem making it difficult to get a pump head on and off the valve stem. I like your solution.

[@BikeShopGirl]

“Typically” the valve weight is about even to the pin/weld of the rim at the opposite side of the wheel. I think on larger/lighter wheels we may feel a difference but I haven’t noticed on the 20”. How about you?

[@garyharty1902]

@@BikeShopGirl I didn't even consider the weld weight. Good point. And, no, I haven't felt anything with these 20" wheels. It seems in the old days with ball bearing adjustable hubs getting the adjustment just right was more important than today with sealed bearings. I'm just glad someone else moves the magnet. The location so close to the valve stem really gets in the way. 🙂

[@battyobrien8264]

Hello from Ireland. Thank you for your quick fix. I'm back in business.

[@granolatx]

Thank you! Solved my issue quickly!

[@wazzaracing]

This was the issue. Thank you

[@rickw7523]

Hi, I have a bafang front wheel motor and sometimes randomly the speed shows 0km/h when cycling. I believe there's no magnet on the spokes for speed. Do you have any idea how to fix this? I was thinking maybe something with the wiring having poor connection?

[@speterson6292]

Thank you.

[@colmocinnseala88]

Again from Ireland. Many thanks, it worked for me.

[@falcon7554]

Thanks works perfect now

[@BikeShopGirl]

Good to hear

[@David-UK24]

How do you get rid of the spanner icon please!!! 👍

[@BikeShopGirl]

A bike shop will need to plug in to reset your service interval.

[@David-UK24]

@@BikeShopGirl thank you!!

[@adrianyueng3489]

​@@BikeShopGirlhi, how often or how many kms that I have to service the bike? I haven't seen the spanner on my display unit yet because I just got the bike from my sister, so far, it's only done 1200km. Thank you.

[@BikeShopGirl]

@@adrianyueng3489that is determined by the bike shop that built the bike. Some don’t put any interval in so it never shows

[@CarstenNoergaard-wb7qf]

Thank you for this video. You solved my problem 🙂

[@BikeShopGirl]

Glad it helped

[@およよ-y9f]

Thank you. very helpful.

[@hurontoikiy7036]

Hi Arleigh🙂can you please tell us how you did disappear 🔧🔧🔧of the screen????

[@BikeShopGirl]

Only a dealer can do that. It’s a reminder they set at a certain amount of miles/km for you to come back for service

[@hurontoikiy7036]

@@BikeShopGirl thank you ✌️

[@rumple-oz3vs]

Thank You kindly

[@Psander]

I have a Trek Allant+ 5. Does my bike even have one those magnets sitting on a spoke in wheel or does it have it somewhere else? I know it's a shot in the dark but i've tried to google and found nothing :(

[@BikeShopGirl]

There’s a chance you lost it. Which year is yours? The photos I find have a magnet on the spoke.

[@BikeShopGirl]

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[@Psander]

@@BikeShopGirl Thank you for your fast answer and sorry for my late reply. You were right about me losing the magnet. Managed to buy another one which solved the problem. Thank you so much! ✨

[@LuckyLife-zr9si]

Hello. I have error 550. Help me please. What is it?

[@ravikhi4955]

Hello dear i have bosch ebike purion display but the head light is not working i am trying like you guide line press and hold 2 to 5 Sec + button but still not on and not showing light icon on display can you help me for resolve this issue

[@BikeShopGirl]

Has the light ever worked?

[@ravikhi4955]

@@BikeShopGirl yes light is working on other ebike but my bosch light is not working i am trying many time and press the + button but not working and not showing the light icon on screen can you help me please what is the main issue That is board problem or display issue

[@BikeShopGirl]

@@ravikhi4955I think you’ll need to visit a Bosch dealer to ensure that the light is able to be turned on

[@ruthlarsen6591]

Cencer til mo tor

[@fewali131]

Poah you are a women??