diff --git a/src/codes_util.cc b/src/codes_util.cc
index 1b73432f8..3ff4ac353 100644
--- a/src/codes_util.cc
+++ b/src/codes_util.cc
@@ -213,6 +213,38 @@ int is_date_valid(long year, long month, long day, long hour, long minute, doubl
     return 1;
 }
 
+// Return 1 if input date is valid. Otherwise 0
+// Note: In the 24-hour time notation, the day begins at midnight, 00:00 or 0:00,
+// and the last minute of the day begins at 23:59.
+// Where convenient, the notation 24:00 may also be used to refer to midnight
+// at the end of a given date — that is, 24:00 of one day is the same time
+// as 00:00 of the following day
+int is_time_valid(long number)
+{
+    // number should be 4 digits i.e., HHMM
+    // Check if the number is a four-digit integer
+    if (number < 0 || number > 9999) {
+        return 0;
+    }
+
+    // Extract hours and minutes
+    long hours   = number / 100;  // Get the first two digits as hours
+    long minutes = number % 100;  // Get the last two digits as minutes
+
+    // Check if hours are within the valid range (00-23)
+    if (hours < 0 || hours > 24) {
+        return 0;
+    }
+
+    // Check if minutes are within the valid range (00-59)
+    if (minutes < 0 || minutes > 59) {
+        return 0;
+    }
+
+    // All checks pass
+    return 1;
+}
+
 static float float_epsilon(void)
 {
     float floatEps = 1.0;
diff --git a/src/eccodes_prototypes.h b/src/eccodes_prototypes.h
index e26aace4e..db119f1ce 100644
--- a/src/eccodes_prototypes.h
+++ b/src/eccodes_prototypes.h
@@ -1328,6 +1328,7 @@ char* codes_getenv(const char* name);
 int codes_check_grib_ieee_packing_value(int value);
 int codes_flush_sync_close_file(FILE* f);
 int is_date_valid(long year, long month, long day, long hour, long minute, double second);
+int is_time_valid(long number); // number is HHMM
 int compute_scaled_value_and_scale_factor(double input, int64_t scaled_value_max, int64_t scale_factor_max, int64_t* ret_value, int64_t* ret_factor);
 
 /* grib_util.cc*/
diff --git a/src/grib_accessor_class_g2date.cc b/src/grib_accessor_class_g2date.cc
index 4ed01d99e..c85e86b9e 100644
--- a/src/grib_accessor_class_g2date.cc
+++ b/src/grib_accessor_class_g2date.cc
@@ -123,9 +123,9 @@ static void dump(grib_accessor* a, grib_dumper* dumper)
 
 static int unpack_long(grib_accessor* a, long* val, size_t* len)
 {
-    int ret                    = 0;
-    grib_accessor_g2date* self = (grib_accessor_g2date*)a;
+    const grib_accessor_g2date* self = (grib_accessor_g2date*)a;
 
+    int ret = 0;
     long year  = 0;
     long month = 0;
     long day   = 0;
@@ -145,13 +145,12 @@ static int unpack_long(grib_accessor* a, long* val, size_t* len)
     return GRIB_SUCCESS;
 }
 
-/* TODO: Check for a valid date */
 static int pack_long(grib_accessor* a, const long* val, size_t* len)
 {
-    int ret;
-    long v                     = val[0];
-    grib_accessor_g2date* self = (grib_accessor_g2date*)a;
+    const grib_accessor_g2date* self = (grib_accessor_g2date*)a;
 
+    int ret = GRIB_SUCCESS;
+    long v = val[0];
     long year  = 0;
     long month = 0;
     long day   = 0;
@@ -165,6 +164,12 @@ static int pack_long(grib_accessor* a, const long* val, size_t* len)
     v %= 100;
     day = v;
 
+    if (!is_date_valid(year, month, day, 0, 0, 0)) {
+        // ECC-1777: For now just a warning. Will later change to an error
+        fprintf(stderr, "ECCODES WARNING :  %s:%s: Date is not valid! year=%ld month=%ld day=%ld\n",
+                a->cclass->name, __func__, year, month, day);
+    }
+
     if ((ret = grib_set_long_internal(grib_handle_of_accessor(a), self->day, day)) != GRIB_SUCCESS)
         return ret;
     if ((ret = grib_set_long_internal(grib_handle_of_accessor(a), self->month, month)) != GRIB_SUCCESS)
diff --git a/src/grib_accessor_class_time.cc b/src/grib_accessor_class_time.cc
index d38a53b7c..36aa290c9 100644
--- a/src/grib_accessor_class_time.cc
+++ b/src/grib_accessor_class_time.cc
@@ -126,12 +126,11 @@ static void dump(grib_accessor* a, grib_dumper* dumper)
 
 static int unpack_long(grib_accessor* a, long* val, size_t* len)
 {
-    int ret                  = 0;
-    grib_accessor_time* self = (grib_accessor_time*)a;
-    long hour                = 0;
-    long minute              = 0;
-    long second              = 0;
-    grib_handle* hand        = grib_handle_of_accessor(a);
+    const grib_accessor_time* self = (grib_accessor_time*)a;
+
+    int ret = 0;
+    long hour = 0, minute = 0, second = 0;
+    grib_handle* hand = grib_handle_of_accessor(a);
 
     if ((ret = grib_get_long_internal(hand, self->hour, &hour)) != GRIB_SUCCESS)
         return ret;
@@ -160,54 +159,24 @@ static int unpack_long(grib_accessor* a, long* val, size_t* len)
     return GRIB_SUCCESS;
 }
 
-// In the 24-hour time notation, the day begins at midnight, 00:00 or 0:00,
-// and the last minute of the day begins at 23:59.
-// Where convenient, the notation 24:00 may also be used to refer to midnight
-// at the end of a given date — that is, 24:00 of one day is the same time
-// as 00:00 of the following day
-#if 0
-static bool isValidTime(long number)
-{
-    // Check if the number is a four-digit integer
-    if (number < 0 || number > 9999) {
-        return false;
-    }
-
-    // Extract hours and minutes
-    long hours   = number / 100;  // Get the first two digits as hours
-    long minutes = number % 100;  // Get the last two digits as minutes
-
-    // Check if hours are within the valid range (00-23)
-    if (hours < 0 || hours > 24) {
-        return false;
-    }
-
-    // Check if minutes are within the valid range (00-59)
-    if (minutes < 0 || minutes > 59) {
-        return false;
-    }
-
-    // All checks pass
-    return true;
-}
-#endif
-
 static int pack_long(grib_accessor* a, const long* val, size_t* len)
 {
-    int ret                  = 0;
-    long v                   = val[0];
-    grib_accessor_time* self = (grib_accessor_time*)a;
-    grib_handle* hand        = grib_handle_of_accessor(a);
-    long hour                = 0;
-    long minute              = 0;
-    long second              = 0;
+    const grib_accessor_time* self = (grib_accessor_time*)a;
+
+    int ret = 0;
+    long v = val[0];
+    grib_handle* hand = grib_handle_of_accessor(a);
+    long hour = 0, minute = 0, second = 0;
 
     if (*len != 1)
         return GRIB_WRONG_ARRAY_SIZE;
 
-    // if (!isValidTime(v)) {
-    //     return GRIB_ENCODING_ERROR;
-    // }
+    if (!is_time_valid(v)) {
+        // ECC-1777: For now just a warning. Will later change to an error
+        fprintf(stderr, "ECCODES WARNING :  %s:%s: Time is not valid! hour=%ld min=%ld sec=%ld\n",
+                a->cclass->name, __func__, hour, minute, second);
+        // return GRIB_ENCODING_ERROR;
+    }
 
     hour   = v / 100;
     minute = v % 100;
diff --git a/tests/grib_set_fail.sh b/tests/grib_set_fail.sh
index 1d850141e..d4c2a0b4e 100755
--- a/tests/grib_set_fail.sh
+++ b/tests/grib_set_fail.sh
@@ -95,6 +95,18 @@ status=$?
 set -e
 [ $status -ne 0 ]
 
+# Bad date
+# ---------
+input=$ECCODES_SAMPLES_PATH/GRIB2.tmpl
+${tools_dir}/grib_set -s dataDate=20180229 $input $outfile > $temp 2>&1
+cat $temp
+grep -q "Date is not valid" $temp
+
+${tools_dir}/grib_set -s dataTime=4261 $input $outfile > $temp 2>&1
+cat $temp
+grep -q "Time is not valid" $temp
+
+
 # ECC-1359: string that can be converted to an integer
 # ---------------------------------------------------
 ${tools_dir}/grib_set -s month:s=6 $ECCODES_SAMPLES_PATH/GRIB2.tmpl $outfile