2003 2.5 Z4 wont start

TcS Trippin

TcS Trippin

Member
 Bristol
Hope everyone is well, i got locked out of my car this morning luckily the boot was accidently slightly open and I got my small friend to climb inside to turn the key, as the mechanical insert on the door just spins, has done since I got the car, anyways the car didn't start atall when turning the key in ignition so brought a new battery and the car has life again all lights on the dash etc but when I go to crank it, nothing happens no noise, im now getting a code 27A4 interface EWS 3.3-DME any help would be awesome, as starting to loose my patience with this car after constant every week fixing.
 
That sounds like the DME and EWS have had a disagreement!
First thing I would do is disconnect the battery for ten minutes just in case it all got a bit confused.
Especially if your friend was turning the key in the ignition before he'd unlocked the car.

I've had the spinning key issue before. A small locking tab had fallen out of the door barrel. You'd need to remove it from the car to repair it.
 
enuff_zed said:
That sounds like the DME and EWS have had a disagreement!
First thing I would do is disconnect the battery for ten minutes just in case it all got a bit confused.
Especially if your friend was turning the key in the ignition before he'd unlocked the car.

I've had the spinning key issue before. A small locking tab had fallen out of the door barrel. You'd need to remove it from the car to repair it.
Click to expand...
Thank you ill try the disconnecting the battery for a while, i just did a successful key pair but that still hasn't fixed it!
 
Key pairing is to the GM5 for locking and unlocking.
Inside the key is a transponder that replies to a check signal from the EWS for starting the car. That is a completely different system.
 
Update, removed seats checked under trim for any wetness didn't find any and checked under trim in boot for wetness could find anything, unplugged battery for 15mins but still nothing aha
 
OK, well we can always assume that the code was already there and irrelevant I suppose.
In which case it could be either the starter motor or the ignition switch.

Have you cleared that code? If so, has it come back?
 
enuff_zed said:
OK, well we can always assume that the code was already there and irrelevant I suppose.
In which case it could be either the starter motor or the ignition switch.

Have you cleared that code? If so, has it come back?
Click to expand...
Yeah cleared it but comes back everytime!
 
Does anybody know anyone who could map out my EWS on my ms43 ECU, as I think thats the last thing to check, just check all the fuses aswell there all good!
 
A search on that code reveals this
The 27A4 fault code indicates a loss of synchronization between the EWS 3.3 (immobilizer) and the DME (engine management) modules, or a communication failure between them. This issue typically prevents the engine from starting or cranking because the DME does not receive the correct rolling security code from the EWS to allow ignition.

Common causes and solutions include:

  • Synchronization Loss: The most frequent cause is a desync of the rolling security codes, often triggered by battery disconnection, diagnostic tool errors, or power interruptions.
  • Diagnostic Tools: Standard OBD scanners (like Foxwell) often cannot clear this code or may even cause the desync. ISTA+ or INPA software with a compatible K+DCAN cable is required to properly reset or re-synchronize the DME and EWS modules.
  • Hardware Issues: If synchronization fails, the problem may stem from cold solder joints on the DME circuit board (common in MS45 variants), a faulty EWS module, or damaged wiring/connectors between the ignition barrel antenna ring and the EWS unit.
  • Key Problems: A dead key battery or a damaged transponder chip can also prevent the EWS from reading the key, resulting in this interface error.

  • It sounds like your EWS and DME have lost their sycnc hence no starting. You need to Re-sync them using software or a Scanner that can do it, I think BMw Scanner1.4 can do it as well as BMW INPA on a Laptop.
 
colb said:
A search on that code reveals this
The 27A4 fault code indicates a loss of synchronization between the EWS 3.3 (immobilizer) and the DME (engine management) modules, or a communication failure between them. This issue typically prevents the engine from starting or cranking because the DME does not receive the correct rolling security code from the EWS to allow ignition.

Common causes and solutions include:

  • Synchronization Loss: The most frequent cause is a desync of the rolling security codes, often triggered by battery disconnection, diagnostic tool errors, or power interruptions.
  • Diagnostic Tools: Standard OBD scanners (like Foxwell) often cannot clear this code or may even cause the desync. ISTA+ or INPA software with a compatible K+DCAN cable is required to properly reset or re-synchronize the DME and EWS modules.
  • Hardware Issues: If synchronization fails, the problem may stem from cold solder joints on the DME circuit board (common in MS45 variants), a faulty EWS module, or damaged wiring/connectors between the ignition barrel antenna ring and the EWS unit.
  • Key Problems: A dead key battery or a damaged transponder chip can also prevent the EWS from reading the key, resulting in this interface error.

  • It sounds like your EWS and DME have lost their sycnc hence no starting. You need to Re-sync them using software or a Scanner that can do it, I think BMw Scanner1.4 can do it as well as BMW INPA on a Laptop.
Click to expand...
Thank you for your detailed help ill look into it!!!
 
Zedshed Cymru enthusiasts What's App Group based in Newport South Wales is a group catering for Z3 and Z4 cars. My home garage with a lift is used to do jobs on our cars owners supply parts oils etc and jobs get done for a donation towards shed running costs, full diagnostics software available. DZm me your phone number if you would like to join us, quite a few Bristol based members already members. I am away over the next 10 days so not available to make a house call to see if I can get your car re-synced.
 
Final Update to help anyone else having the same issue, managed to get the car started and now all is good, I did something very stupid when initially the battery died and I couldn't get into the car I started by replacing the battery in the key and changing the cars battery whilst I was in the key which Is not a real bmw one there was a tiny bit of plastic that fell out and I thought it was a tiny bit of plastic turns out to be the transponder chip, I only figured this out after taking up most of the interior checking wires, checking all the fuses, replacing the ignition switch, having a BMW diagnostic man come out who wasn't to sure of the issue and chewing Colbs ear off about this issue. Only then I realised after researching the issue I payed a nice man to put a new chip in and code the EWS and now all is good!!
 
How refreshing for someone to own up to a genuine mistake and publicise it for future reference to the whole group.
Thank you.
Glad it’s all sorted.
 
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