[Nickyc25]

My ecu has failed on my 320d 2005 e90 I got ecu cas unit + key from another 320d 2005 fitted all parts car won't start took it to indecent BMW for coding they say it can't be coded to my car because already coded to the other car is this true

[Subzero2003]

My knowledge isn't great on things ECU - but replacing an ECU is not as simply as buying another and fitting it. I imagine it is hugely complicated and there are many other modules which are coded to this ECU. IIRC, replacing and coding a new ECU is extremely expensive, time consuming and complicated, with the added risk of damaging other parts of the system in the process.

Not being funny, but did you do any kind of research or talk to anyone "in the know" before undertaking this?

[doughboy]

Why did you replace the CAS unit too?

ECUs do fail from time to time and they're sure to be replaced with just a new ECU, some coding maybe.

Why mess with locks / keys / CAS?

[Nickyc25]

I spoke to a BMW breakers who said the immobiliser went through the key cas unit + ecu so by replacing all 3 of a 320d which were all coded together would work but it hasnt

[Subzero2003]

But the key, CAS unit and ECU aren't the only things that need coding. Everything on the car is coded to your old ECU etc. So now you have a number of components that are coded to your old ECU, but a ECU from a different car.

What a mess!

[doughboy]

Breakers are good with gas axes and crushers, but I wouldn't trust them with much else

[makkan00]

Start from scratch.
Get somebody with bmw equipment.
They need to write your car's VIN to ecu and then code it.
Same goes for CAS and later adding keys.

[Nickyc25]

Car has Ben put back to origanal key + cas unit just ecu changed now waiting to hear from the garage