Posts: 18
Joined: Sun Dec 17, 2017 2:34 am

Re: Engine check light

Wed Aug 05, 2020 4:06 am

When you mention they refuse to replace the "fuel pump sensor" - I hope you are not referring to the fuel pump relay that sits next to the fuses (under the glove box)?

To change that sucker is step numero uno whenever you have any REX issues.
People have swaped out complete engines to find the relay at fault in the end.

You can change it DIY and the part is approx. 15.- Euro! ... 1/61_3564/

How to:

Posts: 28
Joined: Sun Jul 09, 2017 11:07 am

Re: Engine check light

Sun Aug 09, 2020 5:41 am

Latest and hopefully final update. Car back from main dealer. In the end they replaced the fuel pump relay. They said there was pitting on the relay and suspected the pump was faulty and drawing too much current.

I even said to check the relay followingvthe forum's advice as mentioned that their I3 tech has never had to replace one?

Difficult to argue with main dealer, as they have the software and supposed knowledge.

Only saving grace is after £1k GDP the pump, relay and NOx sensor are all covered with 2 year parts and labour warranty should it reoccur.

Posts: 18
Joined: Sun Dec 17, 2017 2:34 am

Re: Engine check light

Tue Aug 11, 2020 5:32 am

Very smooth move by the dealership :-)

In order to justify the pump replacement (which didn't solve the problem and was probably comletely unecessary) , they diagnose that the "faulty" pump damaged the relais.

What a load of BS :-) :-) :-)

But I guess there is no way to prove that they are making this up as they go along !

Keep my fingers crossed for you that the car is back to normal .

Posts: 5036
Joined: Thu May 22, 2014 2:07 pm
Location: Nashua, NH USA

Re: Engine check light

Tue Aug 11, 2020 12:53 pm

A defective pump might pull more current than it should, but typically, that would blow the fuse before it would pit the relay. An intermittent, though, if that caused the relay to open/close frequently could do that. When in the military, on the relay coil, they always seemed to install a diode across the coil to prevent the relay from chattering when the coil was deenergized. Collapsing the magnetic field in the relay coil generates a (usually small) spike or oscillation that an sometimes mess with other electronics.
Jim DeBruycker
2011 535i x-drive GT, 2014 i3 BEV
Soon (hopefully!) A 2021 X5 45e will replace the above

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