diff --git a/extended/code_update/host_multi_code_update.robot b/extended/code_update/host_multi_code_update.robot
new file mode 100644
index 0000000..5366265
--- /dev/null
+++ b/extended/code_update/host_multi_code_update.robot
@@ -0,0 +1,65 @@
+*** Settings ***
+Documentation    Verify that the host boots between code updates of different
+...              PNOR version. Verify with N, the current version, downgrade
+...              and verify with N-1, update and verify N again, and finally
+...              update and verify with N+1.
+
+Library           ../../lib/code_update_utils.py
+Variables         ../../data/variables.py
+Resource          ../../lib/boot_utils.robot
+Resource          ../../lib/code_update_utils.robot
+Resource          ../../lib/openbmc_ffdc.robot
+
+Suite Setup       Suite Setup Execution
+
+Test Teardown     FFDC On Test Case Fail
+
+*** Variables ***
+
+${QUIET}                        ${1}
+${IMAGE_FILE_PATH}              ${EMPTY}
+${N_MINUS_ONE_IMAGE_FILE_PATH}  ${EMPTY}
+${N_PLUS_ONE_IMAGE_FILE_PATH}   ${EMPTY}
+
+*** Test Cases ***
+
+Host_Multi Code Update
+    [Documentation]  Do four code updates in a row. Update to N, N-1, N, and
+    ...              then N+1.
+    [Tags]  Host_Mult_Code_Update
+    [Template]  Code Update And Power On Host
+
+    # Image File Path
+    ${IMAGE_FILE_PATH}
+    ${N_MINUS_ONE_IMAGE_FILE_PATH}
+    ${IMAGE_FILE_PATH}
+    ${N_PLUS_ONE_IMAGE_FILE_PATH}
+
+
+*** Keywords ***
+
+Suite Setup Execution
+    [Documentation]  Do test suite setup tasks.
+
+    Should Not Be Empty  ${IMAGE_FILE_PATH}  msg=Must set IMAGE_FILE_PATH.
+    Should Not Be Empty  ${N_MINUS_ONE_IMAGE_FILE_PATH}
+    ...  msg=Must set N_MINUS_ONE_IMAGE_FILE_PATH.
+    Should Not Be Empty  ${N_PLUS_ONE_IMAGE_FILE_PATH}
+    ...  msg=N_PLUS_ONE_IMAGE_FILE_PATH.
+    Should Not Be Empty  ${OS_HOST}  msg=Must set OS_HOST.
+    Should Not Be Empty  ${OS_USERNAME}  msg=Must set OS_USERNAME.
+    Should Not Be Empty  ${OS_PASSWORD}  msg=Must set OS_PASSWORD.
+
+
+Code Update And Power On Host
+    [Documentation]  Shutdown the host, update to the given image, and then
+    ...              verify that the host is able to power on.
+    [Arguments]  ${image_file_path}
+
+    # Description of argument(s):
+    # image_file_path   Path to the host image file.
+
+    REST Power Off  stack_mode=skip  quiet=${1}
+    Delete All PNOR Images
+    Upload And Activate Image  ${image_file_path}
+    REST Power On
diff --git a/lib/resource.txt b/lib/resource.txt
index 34db7a0..4dc06ea 100755
--- a/lib/resource.txt
+++ b/lib/resource.txt
@@ -58,6 +58,10 @@
 ${BAD_IMAGES_DIR_PATH}          ${EMPTY}
 ${SKIP_UPDATE_IF_ACTIVE}        false
 
+# Parameters for doing N-1 and N+1 code updates.
+${N_MINUS_ONE_IMAGE_FILE_PATH}    ${EMPTY}
+${N_PLUS_ONE_IMAGE_FILE_PATH}     ${EMPTY}
+
 # The caller must set this to the string "true" in order to delete images. The
 # code is picky.
 ${DELETE_OLD_PNOR_IMAGES}   false
diff --git a/tools/generate_argumentfile.sh b/tools/generate_argumentfile.sh
index 81ac987..9b1f02c 100755
--- a/tools/generate_argumentfile.sh
+++ b/tools/generate_argumentfile.sh
@@ -30,6 +30,8 @@
 echo "--variable PNOR_IMAGE_FILE_PATH:$PNOR_IMAGE_FILE_PATH" >> $ARG_FILE
 echo "--variable BMC_IMAGE_FILE_PATH:$BMC_IMAGE_FILE_PATH" >> $ARG_FILE
 echo "--variable BAD_IMAGES_DIR_PATH:$BAD_IMAGES_DIR_PATH" >> $ARG_FILE
+echo "--variable N_MINUS_ONE_IMAGE_FILE_PATH:$N_MINUS_ONE_IMAGE_FILE_PATH" >> $ARG_FILE
+echo "--variable N_PLUS_ONE_IMAGE_FILE_PATH:$N_PLUS_ONE_IMAGE_FILE_PATH" >> $ARG_FILE
 echo "--variable SKIP_UPDATE_IF_ACTIVE:$SKIP_UPDATE_IF_ACTIVE" >> $ARG_FILE
 echo "--variable DELETE_OLD_PNOR_IMAGES:$DELETE_OLD_PNOR_IMAGES" >> $ARG_FILE
 echo "--variable DELETE_OLD_GUARD_FILE:$DELETE_OLD_GUARD_FILE" >> $ARG_FILE