diff --git a/extended/code_update/bmc_code_update.robot b/extended/code_update/bmc_code_update.robot
index b462e1f..71395f7 100644
--- a/extended/code_update/bmc_code_update.robot
+++ b/extended/code_update/bmc_code_update.robot
@@ -42,6 +42,17 @@
     ${ALTERNATE_IMAGE_FILE_PATH}   ${VERSION_PURPOSE_BMC}
 
 
+BMC Set Priority To Invalid Values
+    [Documentation]  Attempt to set the priority of an image to an invalid
+    ...              value and expect an error.
+    [Tags]  BMC_Set_Priority_To_Invalid_Values
+    [Template]  Set Priority To Invalid Value And Expect Error
+
+    # Version Type              Priority
+    ${VERSION_PURPOSE_BMC}     ${-1}
+    ${VERSION_PURPOSE_BMC}     ${256}
+
+
 Delete BMC Image
     [Documentation]  Delete a BMC image from the BMC flash chip.
     [Tags]  Delete_BMC_Image
diff --git a/extended/code_update/host_code_update.robot b/extended/code_update/host_code_update.robot
index 6d250bd..df16823 100644
--- a/extended/code_update/host_code_update.robot
+++ b/extended/code_update/host_code_update.robot
@@ -75,6 +75,17 @@
     Priority          ${127}
 
 
+Host Set Priority To Invalid Values
+    [Documentation]  Attempt to set the priority of an image to an invalid
+    ...              value and expect an error.
+    [Tags]  Host_Set_Priority_To_Invalid_Values
+    [Template]  Set Priority To Invalid Value And Expect Error
+
+    # Version Type              Priority
+    ${VERSION_PURPOSE_HOST}    ${-1}
+    ${VERSION_PURPOSE_HOST}    ${256}
+
+
 Set RequestedActivation To None
     [Documentation]  Set the RequestedActivation of the image to None and
     ...              verify that it is in fact set to None.
diff --git a/lib/code_update_utils.robot b/lib/code_update_utils.robot
index 5286b6a..2346147 100644
--- a/lib/code_update_utils.robot
+++ b/lib/code_update_utils.robot
@@ -114,6 +114,26 @@
     ...  &{cur_properties}[${property}]
 
 
+Set Priority To Invalid Value And Expect Error
+    [Documentation]  Set the priority of an image to an invalid value and
+    ...              check that an error was returned.
+    [Arguments]  ${version_type}  ${priority}
+
+    # Description of argument(s):
+    # version_type  Either BMC or host version purpose.
+    #               (e.g. "xyz.openbmc_project.Software.Version.VersionPurpose.BMC"
+    #                     "xyz.openbmc_project.Software.Version.VersionPurpose.Host").
+    # priority      The priority value to set. Should be an integer outside of
+    #               the range of 0 through 255.
+
+    ${images}=  Get Software Objects  version_type=${version_type}
+    ${num_images}=  Get Length  ${images}
+    Should Be True  0 < ${num_images}
+
+    Run Keyword And Expect Error  403 != 200
+    ...  Set Host Software Property  @{images}[0]  Priority  ${priority}
+
+
 Upload And Activate Image
     [Documentation]  Upload an image to the BMC and activate it with REST.
     [Arguments]  ${image_file_path}