Can not modify header information - headers already sent ... in Codeigniter

How about, I'm inserting data and an image in Codeigniter by means of a form, all that works, but it sends me the following:     

Severity: Warning

Message: Can not modify header information - headers already sent by (output started at /xxx/xxx/xxxx/xxxx/application/controllers/MController.php:78)

Filename: helpers / url_helper.php

Line Number: 564

Backtrace:

File: /xxx/xxxx/xxxxx/xxxx/application/models/MModel.php Line: 124 Function: redirect

File: /xxx/xxx/xxx/xxxx/application/controllers/MController.php Line: 94 Function: insert Test

The error you flag is in MController on line 78 ,

public function add(){


         $config['upload_path'] = './imagenes/';
         $config['allowed_types'] = 'gif|jpg|png|jpeg';
         $config.... 
  {
  echo("<script>console.log('Error al subir la imagen');</script>");
  $error = array('error' => $this->upload->display_errors());
  }
  else
  {

   echo("<script>console.log('Imagen subida correctamente');</script>");// <---Aquí marca error, línea 78

  }

In MModel the line that marks error is the 124 :

public function insertPrueba($data){

                $this->db->insert(TABLE_PRODUCTO,$data);
              redirect('MController');// Aquí marca el error

        }

In index () of MController I load some data that I want to show and load static pages:

public function index()
 {




        $data['me'] = $this->MModel->getAll();
        $data['mB'] = $this->MModel->getAllB();
        $data['mP'] = $this->MModel->getAllP();
    $data['cat'] = $this->MModel->getAllCat();


        $this->load->view('estaticos/header');
        $this->load->view('dinamicos/menu/menus', $data);
        $this->load->view('estaticos/menu_izquierdo');
        $this->load->view('estaticos/footer');
        $this->load->view('estaticos/menu_derecho');
    }

I do not know if I have anything to do with using redirect('MController'); ...

I have reviewed these answers, but I do not have blank spaces starting <?php or at the end ... or anything of the possible causes .. How to fix "Headers already sent" error in PHP