Yes you can check to see if the CSR you generate is valid before trying to activate the SSL certificate.
Please follow the appropriate link:
Comodo certificate users:
https://secure.comodo.net/utilities/decodeCSR.html
Rapid SSL,Quick SSL, Quick SSL Premium, TrueBusinessID with EV certificate users:
https://products.geotrust.com/orders/quickssl.do.
Click on 'Continue' button at the end of the page to verify your CSR