[sam-able]

I'm really hoping someone can give me some guidance as to where I check next - I know I'm new here (save posts about this same issue ages ago I'd imagine) but any help would be much appreciated.

2006 e91 330d M57D30TÜ2

For a couple of years now I've had an intermittent problem where the car would start fine first time, but then when I next turned off the engine it might not recognise the key and so wouldn't start. The key light would sometimes come on while I was driving but wouldn't cause any issues until I turned it off and tried to start it again.

It happened occasionally so I didn't think much of it once I realised I'd usually be fine (and ADHD means these things rarely stick in my head longer than they're in front of me if they're not causing grief!). The problem got more regular but then I took it for an MOT, the issue was gone. Garage said they'd cleared some codes, said they'd tell me which ones but never did. Anyway, issue gone for now.

I realised over time that the issue would return during the summer - in higher temperatures, and would get better in the winter. It was still very intermittent though so - to the back of my mind.

Over the last few months though, the issue has gotten worse, to the point that it likely won't start even first time and I won't risk driving it if I can't get stuck somewhere (I also had a battery issue, so battery was running flat while trying to start it, and jump pack was dying in the time it might or might not recognise the key).

SO... so far I've replaced:

• The battery - seems the last one someone put in was only an 80ah battery. I hoped that might fix the issues, but no.
• The key fob slot.
• The battery in my (non CA) key fob.
• The alternator is relatively new.
• The main battery cable has been replaced.

Current codes via Bimmerlink are as follows:

Junction Box electronics
2 errors
A6D1: ADDITIONAL WATER PUMP
A6CF: AUC_SENSOR

Digital Diesel Electronics
9 errors
4212: 4212 glow plug cylinder 1, control
4252: 4252 Gluehkerze cylinder 5, control
4262: 4262 Gluehkerze cylinder 6, control
4271: 4271 Gluehkerze cylinder 7, control
4281: 4281 Gluehkerze cylinder 8, control
4A27: 4A27 Intelligent Battery Sensor (Layer_DIBS1)
3EFC: 3EFC Thermal Oil Level Sensor (Layer_TOENS)
4232: 4232 glow plug cylinder 3, control
4B37: 4B37 Oil Quality Sensor (Layer_QLT)

Gateway
2 errors
E18D: Awakening device has 3 times unsuccessfully tried to wake up the network.
(Error_WakeUp_Failed).
E190: Ring fracture diagnosis was performed (Error_Ring_Diagnose).

Points to note: I don't seem to have the IBS fitted, my bluetooth unit died ages ago which might explain the E18D fault. ANd yes, I know I finally need to get the glowplugs done, but when it recognises the key it still starts fine even in the cold (please don't tell me this is glowplug related!)

I'm going to check fuses today which I perhaps should have done before now, and when I get the time I'm going to check that the ribbon cable to the key fob slot is good and in-tact.

The intermittent with decline to more permanent nature of the problem suggests something deteriorating rather than electronics going bad, so maybe the cable is the one.

Otherwise, what should I be looking at?

I have INPA, tool32 and ntsexpert, but not sure the install is good as I don't seem to have the profiles I keep seeing suggested, so have downloaded a new copy of those plus Rheingold.

How can I more thoroughly check the CAS unit? No codes necessarily suggest a problem there.

Anyway, for anyone that made it this far, TIA.