Engine management light illuminated constantly

[JamesInLondon]

On Tuesday my main battery was down to 5% and the Range Extender started, I drove with the engine running for 2 or 3 miles. Then parked the car on the street whilst I moved my other car out of the driveway. I then got back in the i3 to pull it into my driveway and charge it, as I started the car, the amber engine management light lit up and has remained on since. I have driven the car on both the battery and the Range Extender since then with no problems, but the light remains on.

My BMW service centre has given me an appointment in 4 weeks time, which is the earliest that they can, so - in the meantime - does anyone have any ideas as to what might be wrong?

Thanks.

 

[mojo]

Probably the best thing to do if you want further insight into the problem is to have the diagnostic codes read - this is the first thing that the BMW service centre will do anyway.

An alternative would be to guess what the problem might be - but of course trying to take action based on guesses is risky, so it's generally not that helpful, in real terms.

 

[JamesInLondon]

My local BMW dealer had the car for 36 hours, couldn't find anything wrong, cleared the fault and told me to keep an eye on the dash to see if the EM light returns - if it does, then the engine will have to be dropped to be checked.

The balance of the time was having the BMW Advanced Car Eye dash cam fitted, let's see how that works.

 

[JamesInLondon]

And exactly one week after returning from the dealer, the problem has arisen again. I took the car yesterday on a 50 mile round trip, I thought that I would try the RX on the return leg. I turned it on and everything was fine until about 5 miles from home the dreaded "Only electric drive available" message appeared. And the engine management light came on and has remained lit.

We are going away for a month on Wednesday, so there is no time to get the dealer to re-examine the car; my question is - should I leave the car on charge whilst we are away or not? The powertrain battery is at about 70% charged. and the 12v battery is less than 6 months old.

 

[alohart]

We are going away for a month on Wednesday, so there is no time to get the dealer to re-examine the car; my question is - should I leave the car on charge whilst we are away or not? The powertrain battery is at about 70% charged. and the 12v battery is less than 6 months old.

Leaving your i3 plugged in would fully charge the battery pack. Leaving a battery pack at a full charge (~95% of its maximum charge due to an unusable 5%) results in a bit faster cell degradation than if it were left at a lower charge level. The self-discharge rate of the HV battery pack is very low, ~1% per month, so it would be fine at 70%.

Your 12 V battery shouldn't discharge in 1 month. Several of us with battery monitors installed have noticed that the DC-DC converter will turn on automatically for an hour when the 12 V battery's voltage drops below a certain level, even without an EVSE being plugged in. This happens repeatedly when the 12 V battery's voltage drops below a certain level. This will discharge your HV battery pack very slightly, but it shouldn't be noticeable. The full capacity of your 12 V battery is only 0.24 kWh compared with the remaining ~20 kWh of capacity of your 94 Ah HV battery pack at a 70% charge level.

 

[JamesInLondon]

Whilst we were away over the holidays I received one of those automated survey responses from BMW UK asking about my experience at my recent visit to the dealer.

I responded honestly and discussed my disappointment at having paid for a fault to be fixed and for it to reoccur within days, I clicked "Send" and the survey vanished into some black hole in the world wide web - or so I thought.

At around 11 this morning I got a phone call from the dealer, telling me that they had seen my survey response and that they were sorry that this had happened and that they wanted to get the car fixed. They asked me when it would be convenient to bring it in; on the two previous occasions that they have worked on the car, the earliest dates they could offer were between 30 to 45 days away. So I asked them when they had availability and the response was - "No, when is it convenient for YOU, can you bring it in this afternoon, perhaps?" so we settled on Wednesday morning, which is the earliest that I can make it.

I will let you know the results; but it has proved to me that those seemingly pointless online surveys actually DO have a use and obviously sometimes DO get read.

 

[JamesInLondon]

So, the dealer has informed me that the crankshaft sensor is most likely the root of the problem and that replacing it involves removing the REX, costing around £2,000 in labour alone.

Has anyone else had this problem and how was it solved?

 

[Ollie]

There is a post on here somewhere where this exact problem was spoken about. The post stated that his mechanic was able to contort himself and replace said part without having to drop the Rex. Not easy but apparently doable. At least I hope it was crank and not cam.

 

[JamesInLondon]

The BMW dealer gave me a quote of around £3,000 to drop the engine and replace the sensor; I called Wisely (who sold me the car 3 years ago) and they did the job for less than half of what the BMW folks wanted.