Petrol engines of N series uses electric water pump. Older ones use pump with 480W power, for newer engines the power of it reaches 700W.

BMW electric waterpump

This knot also isn’t without oddities. Everything looks nice – communication via serial interface, control of all (temperature, load, self-diagnostics etc.) parameters, intelligent management, but…


Error messages, which applies to this water pump:

2E81 electrical cooling pump: speed deviation

2E82 electrical cooling pump: switch off

2E83 electrical cooling pump: low-power modem

2E84 electrical cooling pump: communication

2E85 electrical cooling pump: communication


When you read the documentation, you will come to an conclusion, that control module can stop responding, if there are rapid supply voltage fluctuations. The TIS documents gives an indirect hint – in case of error messages 2E81 and 2E85 it recommends to disconnect/connect battery and delete the error messages.

If you have only error message 2E85 – the situation is worse… If you read the full description of it, you will find out, that this error message points out also to problems of power supply to control module.

When we disarrange this Pierburg – produced item, we can draw conclusions, that electrolytic capacitor is used to stabilize the power supply of control module. This component, which costs roughly 10 cents per piece, has a resource of 3000 .. 5000 working hours at maximal temperature… And it is as long as it is able to perform… Formally, 3000 working hours are approximately 100’000 km – the end of warranty for a vehicle. Isn’t it wonderful???


If the Electric water-pump of your vehicle gives error messages:

2E84 electrical cooling pump, communication


2E85 electrical cooling pump, communication,

you can try to open the pump and replace power supply capacitor (it’s located on the backside, above PCB).