Throttle Body Sensor

[Cruiser Craig]

After replacing the head on my Petrol 1FZFE engine the engine light stays on, I've had it cleared and the mechanic told me the fault was a faulty throttle body sensor, I've read different reports on similar sites and most people say changing it costs around $600 but is not garenteed to fix the fault. Anyone else have this problem or know how to fix it.