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CAS4/CAS4+ ISN mismatch — BMW F/E-chassis CAS4 ISN doesn't match DME

BMW diagnostic code. Below: what it means, common causes, symptoms, and the exact bench-programming fix path.

Common causes

  • •Donor CAS4 installed
  • •Donor DME installed
  • •Failed coding rewrite
  • •Battery drop during ISN write

Symptoms you'll see

  • •Crank-no-start
  • •CAS-DME comm fault
  • •Existing keys rejected

The fix path

Ship CAS4 + DME together. BMW CAS Key Programming ($150) reads DME ISN, writes to CAS, pairs keys.

AML services that fix this

Mail in the affected module, we bench-program, typically ship back next business day. Flat pricing, flat-rate return shipping at checkout.

BMW CAS Module Key Programming (2006-2012)

$150

Lost every BMW key, or the car stopped recognizing the one you have? Ship your CAS module — we program a new working key. Covers CAS2, CAS3, CAS3+, CAS4, CAS4+ — on CAS3+ and CAS4+ ship the DME with the CAS, the new key's ISN is read from it.

Service details

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Related diagnostic codes

P1570Engine Start Blocked by ImmobilizerP0513Incorrect Immobilizer KeyFRM/FRM3 not detectedBMW FRM/FRM3 Footwell Module unresponsiveEWS-DME comm errorEWS module not authenticating with DMECAS-DME comm errorCAS module unable to authorize startBMW E46 cluster pixel lossBMW E38/E39/E46 instrument cluster pixel dropouts

Not sure which service applies?

Text us your year/make/model + which scanner caught the code — we'll tell you exactly which module to ship and which service to pick.

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