How to send error http status code?

[eluser]Unknown[/eluser]
I'd like to return a non-200 status code to the client if an error occurs. The output class has a set_header and I tried it:

Code:

$this->output->set_header("HTTP/1.1 500 Internal Server Error");

but that doesn't work. Neither does the standard PHP

Code:

http_send_status($status)

method.

Any ideas?

Thanks!