Here are the steps to Increase Error Code Process property text lenght for Siebel Workflow :

1.    Login to Siebel tools using SADMIN/SADMIN.
2.    Navigate to object definition "Business Component".
3.    Search for the Name "Repository WF Step" which is based on Table "S_WFR_STP".
4.    Now go to Field definition and search for the field "Error Code" which is based on Column "ERROR_CD".
5.    The default "Text Length" Property for the "Error Code" field is 75 with Type "DTYPE_TEXT".
6.    Now go to Object definition "Table" and search for Table name "S_WFR_STP".
7.    Hit Keyboard shortcut "Alt +L" to Lock the Current selected Object definitions.
8.    Go to Sub Object definition "Column" for the table "S_WFR_STP" and create Copy Record of Column "ERROR_CD" and Make the Text Lenght Property as Required.
9.    Click on Apply/DDL button and then Click on Activate Button to Activate the Table definition.
10.  Go back to object definition "Business Component" and Search for the Name "Repository WF Step" which is based on Table "S_WFR_STP".
11.   Hit Keyboard shortcut "Alt +L" to Lock the Current selected Object definitions.
12.   Now go to Field definition and search for the field Name "Error Code".
13.   Change the "Text Length" Property for the "Error Code" field as Declared in above step (7).
14.   Compile all the Locked projects.