Error code P1503 : key or immobiliser issue ?

[Dark Diver]

Hello all,
Further to an engine replacement, my Corsa did not start and the engine light (EML) is now flashing. Here is the whole story: http://www.corsa-b.co.uk/forum/viewtopi ... 54&t=20720.
So I purchased an OP-COM and I do have a P1503 error code:

P1503 - Immobiliser Wrong Signal
(00) - Present

My question is to know whether the transponder (the chip in the key, I mean) is dead or de-progammed, or this is the immobiliser card which is dead or de-progammed.
BTW, what does the 2nd line mean: (00) - Present ? Does it mean that the immobiliser was found OK, or a transponder was found but not with the right code ?

So what can I do given that I don't have the security code to re-programm the transponder, and before paying Opel to get this code I'd know whether this code will be required or not ?

Thanks in advance for your help.

[johnny]

Have you changed ecu, loom, transponder?

[Dark Diver]

OK, problem solved! The car is running now.
In my previous post I was asking:

- What type of electronics is on the engine, behind the 2 big connectors near the plenum ? As I replaced the engine, maybe the new engine has electronics failure...?

This is the ECU, including the immobiliser. The engine I purchased was provided with an ECU which of course did not recognized my key/transponder.
I reinstalled my ECU and tadaaa: no more error and the engine started.
Too bad nobody replied to my question in my previous post.

And that's strange that Opel/Vauxhall put such a sensitive part in the engine bay where the temparature is high and water can enter. Usually ECUs are in the passenger compartment.