An eCheck results when a payment is sent from an unverified account without sufficient balance in the PayPal account to cover the cost of the order.


PayPal must contact the bank and verify that the funds are present, thus the cause of 3 to 5 days delay.


To avoid sending an eCheck, first complete the verification process for your account, and then make sure the funds are present in PayPal before you place an order. 


To confirm your payment type, just before placing the order you will see a blue hyperlink that reads: “choose more funding options”. By clicking this link you may determine which option is currently selected for your payment and what payment options your account supports.



Reference

What is an eCheck