diff --git a/icu4c/source/common/ucnv_err.c b/icu4c/source/common/ucnv_err.c
index f88af72fea..75659fb571 100644
--- a/icu4c/source/common/ucnv_err.c
+++ b/icu4c/source/common/ucnv_err.c
@@ -245,11 +245,7 @@ UCNV_FROM_U_CALLBACK_ESCAPE (
 
       case UCNV_PRV_ESCAPE_CSS2:
           valueString[valueStringLength++] = (UChar) UNICODE_RS_CODEPOINT;    /* adding \ */
-          if (length == 2) {
-              valueStringLength += uprv_itou (valueString + valueStringLength, VALUE_STRING_LENGTH - valueStringLength, codePoint, 16, 0);
-          } else {
-              valueStringLength += uprv_itou (valueString + valueStringLength, VALUE_STRING_LENGTH - valueStringLength, (uint16_t)codeUnits[0], 16, 0);
-          }
+          valueStringLength += uprv_itou (valueString + valueStringLength, VALUE_STRING_LENGTH - valueStringLength, codePoint, 16, 0);
           /* Always add space character, becase the next character might be whitespace,
              which would erroneously be considered the termination of the escape sequence. */
           valueString[valueStringLength++] = (UChar) UNICODE_SPACE_CODEPOINT;
diff --git a/icu4c/source/common/unicode/ucnv_err.h b/icu4c/source/common/unicode/ucnv_err.h
index e52a39303f..6fde6966cd 100644
--- a/icu4c/source/common/unicode/ucnv_err.h
+++ b/icu4c/source/common/unicode/ucnv_err.h
@@ -140,9 +140,9 @@ typedef struct UConverter UConverter;
 #define UCNV_ESCAPE_UNICODE   "U"
 
 /**
- * FROM_U_CALLBACK_ESCAPE context option to escape the code unit according to CSS2 conventions (\\X{XXXXX} followed by
- * a space.
- * @stable ICU 4.0
+ * FROM_U_CALLBACK_ESCAPE context option to escape the code unit according to CSS2 conventions (\\HH..H<space>, that is,
+ * a backslash, 1..6 hex digits, and a space)
+ * @draft ICU 4.0
  */
 #define UCNV_ESCAPE_CSS2   "S"
 
diff --git a/icu4c/source/test/testdata/conversion.txt b/icu4c/source/test/testdata/conversion.txt
index f7691bccf5..9702dfba9e 100644
--- a/icu4c/source/test/testdata/conversion.txt
+++ b/icu4c/source/test/testdata/conversion.txt
@@ -917,6 +917,14 @@ conversion:table(nofallback) {
           :intvector{ -1,-1,-1,-1,0,1,2,2,2,3,3,5,5,5 },
           :int{1}, :int{1}, "", "?\x00\x2f\x7e", ""
         }
+        // ISO-2022-KR
+        {
+          "ibm-25546",
+          "AB\uc88b\U00050005\uacccC",
+          :bin{           1b24294341420e41410f5c3530303035200e306a0f43 },
+          :intvector{ -1,-1,-1,-1,0,1,2,2,2,3,3,3,3,3,3,3,3,5,5,5,6,6 },
+          :int{1}, :int{1}, "", "&S", ""
+        }
 
         // ISO-2022-JP-2 with G2 designator & SS2 shift
         {