C＃正则表达式搜索包含周围括号的文本字符串

I would like to search a string for '[E1010]' or '[E1011]' or '[E1012]'. Currently, I can only successfully search without using the brackets []. How can I adjust my regex to include the texting surrounded by the brackets as it is in my sClientError variable.I would like to search a string for '[E1010]' o