Crankshaft Position Sensor Error - what happens if I don't fix it?

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New member
Sep 18, 2023
Hello. 2017 BMW i3 Rex here.

So I recently got an error code that says I have a faulty crankshaft position sensor.

My REX will turn on like normal at around 6.5-7% and it works fine it seems. It charges the battery and I can hear it running. Nonetheless, I have that error and the check engine light comes on.

What does the crankshaft position sensor do anyways? What happens if I don't fix it and just use the rex like normal? It seems like its still working...
Wikipedia has a fairly good concise description of what a Crankshaft Position Sensor does:

As the article says, the consequences of failure of the sensor depend on the design of the ignition/injection system, but it's often used in combination with other sensors (e.g. camshaft), so with some designs it's more critical than others.

In the case of the REX, It's quite likely that the engine will run, but not optimally. If it were mine, I would have the sensor replaced. In my part if the world (the UK) the car won't pass an annual inspection with the Engine Management light on, so I would have no choice, longer term.