Engine fault notification

[Pondrew]

Wife got an "engine fault" notification on the i-Drive on her way to work this morning.

Car drove fine but no other information. I told her to phone the AA while at work; hopefully they can read the codes at least. This has spurred me into ordering a code reader (at last). I have ordered the Creator 410; no idea if they are any good.

One question; could an 'engine fault' code be associated with a dodgy battery? The battery hasn't been charged properly for a while as the car is outside and it keeps bloody raining. It has been stood for a few days (maybe a week). Hopefully it is battery related, as the car only has 24k miles on the clock! N20 20i BTW.

 

[Pondrew]

So a little update:

AA man read the codes (pretty good service from AA, only took 1/2 hour to get there).

It had:
3046 Knock sensor 2. Short circuit to earth.
2C58 Boost pressure control. Pressure build up incorrect.

Any ideas?

 

[bigwinn]

I don’t think a low battery will throw an eml… more likely to be abs or similar

But hey it’s a bmw so anything’s possible

 

[bigwinn]

Knock sensor looks like it’s gone south

Not sure about the boost one as I’m not very au fait with forced induction

 

[pvr]

The conversation in the Pondrew household tonight ...

"Why did you sell my old car, never had any issues with that one and nothing but trouble with this new one"

 

[Pondrew]

The conversation in the Pondrew household tonight ...

"Why did you sell my old car, never had any issues with that one and nothing but trouble with this new one"

More likely to be "how much is that going to f*cking cost, then?"

Looking online I'm not sure if the boost code is related to the first or not. Also don't know if either is historical at present. Obviously at least one is new!

 

[Pondrew]

I can't find any reference to the knock sensor code "3046" that came up anywhere. It seems it should be something like 2E68 for a knackered sensor.

Any suggestions with this would be appreciated.

 

[enuff_zed]

I can't find any reference to the knock sensor code "3046" that came up anywhere. It seems it should be something like 2E68 for a knackered sensor.

Any suggestions with this would be appreciated.

When I use the Scanner 1.4 to find faults it gives me the code you expect, with a 4-digit one in brackets after it.
ie. 2E68 (3046)
So possibly they mean the same thing?

 

[enuff_zed]

I found this website that you can plug either format into and it gives the diagnosis.
https://bmwfault.codes/

 

[Pondrew]

I found this website that you can plug either format into and it gives the diagnosis.
https://bmwfault.codes/

Thanks Martin. Very helpful. His scanner wasn't lying then!

So looking up the other 2C58 code on that site, indicates it is as a consequence of another fault; ie isn't a fault in itself (if I read it correctly).
Therefore it seems as though the 2C58 fault (turbo pressure associated) is because of the knock sensor fault.
How would a faulty knock sensor have any bearing (no pun) on turbo pressure, or be related to the turbo?

 

[Pondrew]

So codes cleared by Mr AA.
Car driven 19 miles home without anything out of the ordinary happening. According to the knock sensor code it was a short circuit, so I would expect that code to come straight back but it hasn't.

I have a potential theory which may explain why it has done this....
The car hasn't moved for a good few days. It has been extremely wet and fairly cold during that time. Yesterday the weather warmed up significantly which would cause a lot of condensation in the engine bay (cold damp car, sudden increase in air temp). Everything in my garage was dripping wet yesterday for the same reason.
If there is a slightly loose connection anywhere on that sensor wiring, it could easily have got moisture in there, either indicating a dead short or temporarily creating one.
The car was then fully warm when she arrived at work, left for any residual moisture to evaporate and 'un-short' the sensor/ circuit. The other code only seems a by-product from the sensor one.

Time will tell I suppose

 

[Reamesy]

Just a tip.

When fault finding on cars using code readers you can on some read live data. You can look at the values and compare this with the expected parameters.

However, if you are accessing data through the car ECU; the faulty sensor can be compensated by the car which can then look normal.

So it good practice if you want to see actual live data to access it through OBD11. That way the car does not process data before passing it to the reader. So in theory if the sensor is bad it can be quickly found and then tested to pin point with just random replacement.

 

[Pondrew]

Just a tip.

When fault finding on cars using code readers you can on some read live data. You can look at the values and compare this with the expected parameters.

However, if you are accessing data through the car ECU; the faulty sensor can be compensated by the car which can then look normal.

So it good practice if you want to see actual live data to access it through OBD11. That way the car does not process data before passing it to the reader. So in theory if the sensor is bad it can be quickly found and then tested to pin point with just random replacement.

Thanks matey but TBH none of that means anything to me. I do not 'do' electronics in any shape or form. I can find my way around a spanner but the 'tech' stuff is a no-no.

I am not going to use the car now until my scanner arrives and I can work out how to plug it in and read it. I don't know how good or bad a Creator 410 is TBH, but presume it's pretty basic for £40.

 

[pvr]

Agreed, she can walk to work

 

[Pondrew]

Agreed, she can walk to work

She will take my car, or if she breaks that aswell, the daughter's Mini (which has actually been behaving itself lately).

 

[Busterboo]

I have a potential theory which may explain why it has done this....
The car hasn't moved for a good few days. It has been extremely wet and fairly cold during that time.

The only time our Z isn't under cover overnight is when we're on holiday. Otherwise, it's in a car port under my wife's first-floor office.

It's broken down only twice in 80k miles. Once, a failed injector. The second, after being left outside for 2 nights at the end of January in Noah-esque rain (because SWMBO thought the car port ceiling already looked wet and might collapse on the car). Certainly, the rain was heavier & longer than I can remember seeing in the UK.

The car was then driven hard and left for a while.

So, I reckon you might well be right.