🔍 Diagnostic Case: BMW 3 Series (E90) – No Ignition / No Start
Called out to a 2009 BMW E90 with a complete ignition failure following a flat battery and recharge.
⚠️ Reported Symptoms:
- Key inserts, but no dash lights at all
- No ignition, no crank
- Hazards and alarm still operational
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🔧 Diagnostic Process:
Using the Autel IM508S, we accessed CAS (Car Access System) live data and immediately identified critical issues:
- ❌ “Key not detected” despite key being inserted
- ❌ Clutch input not recognised
- ❌ Terminal 15 (ignition power) not activating (0V confirmed by multimeter)
Despite this, the key transponder was independently verified as fully functional using the Xhorse Key Tool Mini.
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🧠Diagnosis:
This was not a key fault.
Findings pointed to a failure within the ignition activation system, most likely:
- CAS module fault following low voltage event
- OR a fault within the Terminal 15 power circuit (wiring / fuse / relay)
The vehicle showed classic signs of a CAS wake-up failure, including brief system activity (tacho flick) before immediate shutdown.
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âś… Outcome:
Customer was provided with a clear, evidence-based diagnosis and advised to consult an auto electrician for further investigation into CAS or power distribution faults.
No unnecessary parts replaced. No guesswork.
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đź’ˇ Takeaway:
Modern vehicles require proper diagnostics, not assumptions.
Throwing parts at a problem wastes time and money—accurate fault finding saves both.
