This time – a short review of the Bosch ignition coil.
Code of the ignition coil: 0 986 221 124

The ignition coil is delivered in a nice Bosch box:

Electrical parameters of the primary winding. BMW vs Bosch.
Inductance: 1.10/1.15mH (+5%)
The active resistance: 410/330mOhm (-20%)


This ignition coil has good potential for the electric parameters. Both basic parameters – respectable. Of course, the performance of the ignition coil is described with a range of other electric (including the magnetic parameters of the core) and other parameters (the durability of the high-voltage part to the voltage, humidity, temperature, oil, etc.). To evaluate all these parameters, I would need a very specific laboratory. But these basic parameters allow us to quickly evaluate – it or it is not to test the ignition coil in real working conditions.
Anyway, the ignition coils of modern cars are technologically MUCH more complicated than would seem. So, I am completely sure that some cheap alternatives or “sport/tuning” ignition coils in colored bodies are not even worth installing in the engine. These ignition coils will not ensure anything else than the damage of the exhaust (and, maybe, even DME).


To make this entry more interesting, let’s look closer at this ignition coil:

Here, we see a nice Bosch label, but… wait, what’s that?

There are some other inscriptions below this Bosch label!

Let’s remove the label!

Let’s see what this code – R1705S00100 – means.
Wait, this is the ELDOR code!
The ignition coil was manufactured in the Year 2023, but it has the “old design” body.


What can we conclude? Bosch is simply repacking ELDOR ignition coils! Bosch has not even ordered the ignition coils without an inscription. What is even more interesting is that these ignition coils have other codes (as ones that ELDOR installs as OEM/BMW ignition coils).
ELDOR is an average-sized private company with 3400 employees and several factories, including in Turkey. Treu thou, everything is relative, because, for example, Bosch has 100(!) times more employees!