bosch performance cX 4 th generation. ERROR 503

[Silpa]

Hi everyone, I am the owner of a Lombardo dc90 ebike
fitted with a 4th generation bosch performance cx. For some time (about 1 month) I mounted a modification to exceed 25 km / h. The modification is called eplus (Chip Bosch - Ebike Tuning).
One day the bike no longer gave assistance and I solved it by returning to its original state and removing the chip. The bike ran smoothly for about 2 months after disassembling the chip.
After about 2 months from the disassembly of the chip, I get the error message 503.
I took the bike to a bosch center and they replaced the battery first, then the charger. I thought I had solved it but again I get error 503.
I mount the slim speed sensor and the appropriate magnet.
I have had the electronic diagnosis done several times and the chip I had installed never resulted from the diagnosis. I have now ordered a new sensor and magnet and they must arrive.
Do you think it can solve or do you think it depends on the assembly of that chip that I removed? Thanks everyone for the answers.

 

[Rusty]

Stolen from somewhere when I got a 503 - mine was lined up with the bolt and not the sensor. Apparently this is pretty common.

 

[Silpa]

thank you. But I mount this type of sensor e magnets.

 

[RustyMTB]

A 503 error is a speed sensor error, usually around the magnet becoming misaligned with the sensor. Bosch recommend the magnet should be spaced between 8-14mm from the sensor. Your bike is the same as a Decathlon Stilus, so the magnet is mounted on the spokes. I would look there first.

I have also seen on here a guy who had ££££ of warranty work done chasing the same error only to discover the speed sensor wire wasn't fully pushed in to its connector at the motor.

 

[PenSki]

I had 503 error recently. It was a drop of water inside the speed sensor connector at the motor connection.

 

[Silpa]

Today I try to check the wire harness to the engine. For the sensor I mount a different one and the magnet is screwed onto the disc with 2 screws. It cannot move.

 

[simonwwfc]

Stolen from somewhere when I got a 503 - mine was lined up with the bolt and not the sensor. Apparently this is pretty common.
View attachment 93681

So the small magnet doesn’t need to be inline with the black round part ?

 

[Landy Andy]

So the small magnet doesn’t need to be inline with the black round part ?

No. It does not, well it isn’t on my wife’s Ebike that runs this system and hasn’t been touched.

 

[Rusty]

So the small magnet doesn’t need to be inline with the black round part ?

No - that is the bolt. If I run it there I see random 503 errors and occasionally it will just switch off.

 

[slomtbr]

So the small magnet doesn’t need to be inline with the black round part ?

Align the magnet with the line indicated by the arrows.

 

[All4Fun]

The line and distance are important, had some 503 errors here, distance was to big, lined it up with a 5mm gap, but after some months 503 again, changed the gap to 11mm and no more 503's.

 

[Oekaaaeir]

Hi, does that mean one could place the magnet too close? Just making sure I understand this correct.

 

[All4Fun]

Hi, does that mean one could place the magnet too close? Just making sure I understand this correct.

Yes, i can't explain, thought a strong magnetic field would be good, but in my case it didn't work 100% well.
Bosch says for my sensor 5-17 mm.