Car warning light came on, the one with a car and a spanner, then power died, car now only revs to 4k and no boost at all?

Crank shaft sensor maybe?

I did get an ECU light few days ago, took it to a chap who read the ECU faults was the Lambda sensor, cleared the fault and no ECU light back since then.

Not sure the Lambda would kill the engine to limp mode though?

Any ideas