ABS Errors in my 335i

[Ooonst 4]

So I have been getting these ABS and related errors (DBC, FTM, Start assistance) intermittently for the last few days. I have had them in the past, usually on a road trip they will pop up once and hang about until the car is next restarted then disappear and not come back for weeks. They seem to be getting more frequent (or perhaps I'm just driving the car more frequently over summer holidays!?) and as well as these I have a Transmission light that has started showing up now and again. The transmission light is less frequent but more weird and doesn's seem to be related, as in it will show up at different times. I noted today when it was coming on whilst I was stationary with the engine running, the steering wheel seemed to be trying to recalibrate itself, moving small increments left and right but itself (active steering) and the error is mostly showing up when the car is stationary though my wife claimed it hit her whilst she was driving and that the car "shuddered"... Will come back to this one later. 

With the ABS lights, when I've had them in the past, as I had a mechanical breakdown Insurance policy that came with the car, I took the car to the local garage who diagnosed the problem as a rear wheel speed sensor. Assuming that this is the same cause but simply the other wheel, I've ordered a couple (1 for now and one spare) of BOSCH "0986594572" which are apparently a good fit for OE Part 34526870077 https://www.realoem.com/bmw/enUS/partsearch?id=UV72-EUR-01-2009-E91N-BMW-335i&mg=&q=34+52+6+870+077. There appear to be broadly 3 classes of these sensors, the cheap-as-chips Chinese ones that can be had for as little as $18 AUD which I gather are to be avoided, the middle of the road ones from Bosch or ATE for about $70-80 each and the OEM ones which seem to run about $200. I've gone for the "one up from the bottom" on the wine list. Anyone have thoughts on the relative merits of each type of ABS sensor?

I've also been having electrical issues for some time with my battery progressively dying on me due to all manor of additional electrical crap that has been tacked onto the car (android auto/carplay retrofit, Dash cam hardwired). I purchased a Varta E39 70aH AGM replacement for $500 and fitted and coded this myself yesterday (following the PDF instructions from https://www.e90post.com/forums/showpost.php?p=11379622&postcount=48). I was hoping that this might be the remedy for all of the above and was smugly driving around yesterday thinking exactly that until... all the errors came back today. Corelation is not necessarily causation!

I'll have a go at swapping out the ABS sensor when they arrive and report back.

Edited January 18 by Ooonst

[F10er 62]

Sounds like a possible voltage issue. What is the alternator charge rate when engine is running? 

Also it's probably worth noting that your battery is too small. It should be a 90ah.

[Ooonst 4]

Thanks for the advice! There are mixed messages about what sort of battery to stick in. I found this - https://www.autopadre.com/battery-size/bmw-335i which claims that an H6 was the battery it came with. The one I pulled out was an H6 but possible underspec'd at 63AH, 580CCA. I would have thought that AH is roughly how long you can run things and the CCA (Cold crank amps / ability to start the engine) would have been more important?

I got the Varta E39 (AGM) which is H6 size but 70AH and 760CCA so an upgrade in terms of CCA (and AH). The previous battery never seemed to have a problem starting the car unless, on the odd occasion (twice?) it was heading towards flat. I measured the voltage on the old battery after having it out of the car for 3-4 days and it was coming up as 12.43v which is about 75% charge so that battery looks like it's fine but perhaps not really big enough. 

The new battery measures 12.52-12.63v at rest (95% charged) and I'm getting 14.22-14.28v when the Alternator is charging. 

On the DTC side of things, I find it odd that there are mostly none when the dash cluster is lit up! I would have thought that if a DTC is triggered then it's stored in memory until it's manually cleared? That's certainly the way my VAG car computers operate. Is it different for Bimmers?

After driving around this morning and having the intermittent same 4 messages as above I had a couple of instances of the transmission warning light. At one point, the traffic lights went green, I tried to accelerate but pretty sure nothing happened. No rev's going to the engine and no movement / engagement of 1st gear from the car. 5 seconds later it was fine, driving normally. When I got back home I checked the DTC's again and had a long list. The first time I have seen most of these - 

2F4E
2F4F (I've had this one several times before, recently and in isolation which is the Right Rear ABS sensor. I've previously had the same symptoms and had the Left Rear ABS sensor replaced so figure it's time to replace the other one now...)
CD95
CD98
CD9C
CDA1
CDA5
CDA8
CDAD
CDB3
 

Looking at https://www.1addicts.com/forums/showthread.php?t=1990156 and https://www.e90post.com/forums/showthread.php?t=1934018 - Both of these guys, their cars died completely. Thinking about grounding straps and DME relays might be next to check in parallel with sorting out the Rear right ABS sensor. 

 

[F10er 62]

I think those are all CAN bus faults.

If you put your VIN into mdecoder.com you can see what battery your car had from factory. As far as i know all E90s with a CCC or CIC came with a 90ah battery. I could be wrong though.

Edited January 20 by F10er

[F10er 62]

Yes, they are all CAN communication errors for the DSC control unit. I would be checking the power and earth supplies to the DSC and also checking the PT CAN wiring between the DSC and DME, including unplugging them and visually checking the pins for corrosion. Have you got ISTA? 

Edited January 20 by F10er