I'm afraid I have no knowledge of how the Blitz ECU behaves, hence I didn't answer.
The standard ECU detects the fault when the engine goes over 3,000 RPM but nothing is heard from the knock sensor. Once the engine light has come up, the ignition is retarded a fair bit (for safety) which reduced performance and also makes the exhaust run much hotter.
As for 'replacing the cable' - unless there is physical damage the cable itself is unlikely to be faulty - more likely a connector fault, and more likely at the knock sensor end. That's assuming, of course, you have already changed the sensor as that is the most likely thing to fail.
It is a screened cable, with the screen earthed at the ECU end. At the sensor end, the screen is cut short and not connected.
A common mistake is to 'strip' the wire further back to re-make the connector, without realising they have actually now connected the outer and inner strands together, effectively short circuiting the signal. I suspect this is what has lead to the myth of cable failures. To re-make the end properly, carefully remove the outer plastic covering to reveal the outer screen layer. Pull these strands to on side (and cut them off at engine end, connect to earth at ECU end) to reveal the inner plastic cable sleeve. This can then be stripped normally and connected.
screening is normally braid, individual strands right round or a single wire with foil screen. Sometimes, a combination.
Braid:
Foil:
Strands:
