The original part number is A0185453232. The ECU from the E300 can also be reprogrammed for use on the G.

The problem can be resolved by replacing the memory before it fails (so that all of the secret numbers can be copied over) or with a new ECU and having the dealer re-authorize the keys. Since I lost the key information, I chose to remove the immobilizer. This allows the G to be started with a plain metal key.