diff --git a/test/functional/tests/fault_injection/test_fault_injection_many_to_one.py b/test/functional/tests/fault_injection/test_fault_injection_many_to_one.py
new file mode 100644
index 0000000..8852ef6
--- /dev/null
+++ b/test/functional/tests/fault_injection/test_fault_injection_many_to_one.py
@@ -0,0 +1,87 @@
+#
+# Copyright(c) 2020 Intel Corporation
+# SPDX-License-Identifier: BSD-3-Clause-Clear
+#
+
+import pytest
+
+from api.cas import casadm, casadm_parser
+from api.cas.cache_config import CacheMode, SeqCutOffPolicy, CacheModeTrait
+from api.cas.core import Core
+from storage_devices.disk import DiskType, DiskTypeSet, DiskTypeLowerThan
+from core.test_run import TestRun
+from test_tools.dd import Dd
+from test_utils.os_utils import Udev
+from test_utils.size import Size, Unit
+
+block_size = Size(1, Unit.Blocks4096)
+
+
+@pytest.mark.parametrize("cache_mode", CacheMode.with_any_trait(CacheModeTrait.InsertRead
+                                                                | CacheModeTrait.InsertWrite))
+@pytest.mark.require_disk("cache", DiskTypeSet([DiskType.optane, DiskType.nand]))
+@pytest.mark.require_disk("core", DiskTypeLowerThan("cache"))
+def test_one_core_remove(cache_mode):
+    """
+        title: Test if OpenCAS correctly handles removal of one of multiple core devices.
+        description: |
+          When one core device is removed from a cache instance all blocks previously occupied
+          by the data from that core device should be removed. That means that the number of free
+          cache blocks should increase by the number of removed blocks.
+          Test is without pass through mode.
+        pass_criteria:
+          - No system crash.
+          - The remaining core is able to use cache.
+          - Removing core frees cache blocks occupied by this core.
+    """
+    with TestRun.step("Prepare one device for cache and two for core."):
+        cache_dev = TestRun.disks['cache']
+        cache_dev.create_partitions([Size(512, Unit.MebiByte)])
+        cache_dev = cache_dev.partitions[0]
+        core_dev = TestRun.disks['core']
+        core_dev.create_partitions([Size(1, Unit.GibiByte)] * 2)
+        core_part1 = core_dev.partitions[0]
+        core_part2 = core_dev.partitions[1]
+        Udev.disable()
+
+    with TestRun.step("Start cache"):
+        cache = casadm.start_cache(cache_dev, cache_mode, force=True)
+        caches_count = len(casadm_parser.get_caches())
+        if caches_count != 1:
+            TestRun.fail(f"Expected caches count: 1; Actual caches count: {caches_count}.")
+
+    with TestRun.step("Add both core devices to cache."):
+        core1 = cache.add_core(core_part1)
+        core2 = cache.add_core(core_part2)
+        cores_count = len(casadm_parser.get_cores(cache.cache_id))
+        if cores_count != 2:
+            TestRun.fail(f"Expected cores count: 2; Actual cores count: {cores_count}.")
+
+    with TestRun.step("Fill cache with pages from the first core."):
+        dd_builder(cache_mode, core1, cache.size).run()
+        core1_occupied_blocks = core1.get_occupancy()
+        occupied_blocks_before = cache.get_occupancy()
+
+    with TestRun.step("Remove the first core."):
+        cache.remove_core(core1.core_id, True)
+        caches_count = len(casadm_parser.get_caches())
+        if caches_count != 1:
+            TestRun.fail(f"Expected caches count: 1; Actual caches count: {caches_count}.")
+        cores_count = len(casadm_parser.get_cores(cache.cache_id))
+        if cores_count != 1:
+            TestRun.fail(f"Expected cores count: 1; Actual cores count: {cores_count}.")
+
+    with TestRun.step("Check if occupancy from the first core is removed from cache."):
+        # Blocks occupied by the first core should be completely released.
+        if cache.get_occupancy() != occupied_blocks_before - core1_occupied_blocks:
+            TestRun.LOGGER.error("Blocks previously occupied by the first core "
+                                 "aren't released by removing this core.")
+
+    with TestRun.step("Check if the remaining core is able to use cache."):
+        dd_builder(cache_mode, core2, Size(100, Unit.MebiByte)).run()
+        if not float(core2.get_occupancy().get_value()) > 0:
+            TestRun.fail("The remaining core is not able to use cache.")
+
+    with TestRun.step("Stop cache."):
+        casadm.stop_all_caches()
+