diff --git a/Inc/mmr_can.h b/Inc/mmr_can.h
index b1a0a79..d248046 100644
--- a/Inc/mmr_can.h
+++ b/Inc/mmr_can.h
@@ -165,6 +165,7 @@ CanFilterMask MMR_CAN_AlignStandardMask(CanFilterMask baseMask);
 MmrCanFilterSettings MMR_CAN_GetDefaultFilterSettings();
 
 HalStatus MMR_CAN_Send(CanHandle *hcan, MmrCanPacket packet);
+HalStatus MMR_CAN_SendNoTamper(CanHandle *hcan, MmrCanPacket packet);
 HalStatus MMR_CAN_Receive(CanHandle *hcan, MmrCanMessage *result);
 
 #endif /* INC_MMR_CAN_H_ */
diff --git a/Inc/mmr_can_header.h b/Inc/mmr_can_header.h
index 79d5d9f..c5bee49 100644
--- a/Inc/mmr_can_header.h
+++ b/Inc/mmr_can_header.h
@@ -18,6 +18,7 @@
  * Constants with lower values have an higher priority.
  */
 typedef enum {
+  MMR_CAN_MESSAGE_TYPE_SCS = B_(0000),
   MMR_CAN_MESSAGE_TYPE_ACK = B_(0001),
   MMR_CAN_MESSAGE_TYPE_MULTI_FRAME = B_(0010),
   MMR_CAN_MESSAGE_TYPE_MULTI_FRAME_END = B_(0011),
@@ -62,6 +63,12 @@ uint32_t *MMR_CAN_HeaderToBits(MmrCanHeader *header);
  */
 MmrCanHeader *MMR_CAN_HeaderFromBits(uint32_t *bits);
 
+
+/**
+ * @brief
+ * Tells wether the given header represents an SCS.
+ */
+bool MMR_CAN_IsHeaderScs(MmrCanHeader header);
 bool MMR_CAN_IsMultiFrame(MmrCanHeader *header);
 bool MMR_CAN_IsMultiFrameEnd(MmrCanHeader *header);
 
diff --git a/Inc/mmr_can_message_id.h b/Inc/mmr_can_message_id.h
index d917f8d..0f332f1 100644
--- a/Inc/mmr_can_message_id.h
+++ b/Inc/mmr_can_message_id.h
@@ -47,13 +47,6 @@ uint8_t MMR_CAN_GetMessageIdSubtype(MmrCanMessageId msgId);
  */
 bool MMR_CAN_IsMessageIdOfType(MmrCanMessageId msgId, MmrCanMessageIdType type);
 
-/**
- * @brief
- * Tells wether the given message id is
- * represents an SCS.
- */
-bool MMR_CAN_IsMessageIdSCS(MmrCanMessageId msgId);
-
 
 enum MmrCanMessageId {
 // SCS
diff --git a/Inc/mmr_can_scs_manager.h b/Inc/mmr_can_scs_manager.h
index 3e224cc..ee77d17 100644
--- a/Inc/mmr_can_scs_manager.h
+++ b/Inc/mmr_can_scs_manager.h
@@ -50,6 +50,12 @@ typedef enum {
 
 bool MMR_CAN_MaybeHandleAck(MmrCanHeader header);
 HalStatus MMR_CAN_HandleNextScs(CanHandle *hcan);
+
+HalStatus MMR_CAN_SendAck(
+  CanHandle *hcan,
+  MmrCanHeader originalHeader
+);
+
 HalStatus MMR_CAN_SendScs(
   CanHandle *hcan,
   MmrCanMessageId scsId,
diff --git a/Src/mmr_can_header.c b/Src/mmr_can_header.c
index 8ceb707..7298c45 100644
--- a/Src/mmr_can_header.c
+++ b/Src/mmr_can_header.c
@@ -11,6 +11,10 @@ MmrCanHeader *MMR_CAN_HeaderFromBits(uint32_t *bits) {
 }
 
 
+bool MMR_CAN_IsHeaderScs(MmrCanHeader header) {
+  return header.messageType == MMR_CAN_MESSAGE_TYPE_SCS;
+}
+
 bool MMR_CAN_IsMultiFrame(MmrCanHeader *header) {
   return header->messageType == MMR_CAN_MESSAGE_TYPE_MULTI_FRAME;
 }
diff --git a/Src/mmr_can_message_id.c b/Src/mmr_can_message_id.c
index 61f1162..82c0cc7 100644
--- a/Src/mmr_can_message_id.c
+++ b/Src/mmr_can_message_id.c
@@ -1,12 +1,6 @@
 #include <stdint.h>
 #include "mmr_can_message_id.h"
 
-
-bool MMR_CAN_IsMessageIdSCS(MmrCanMessageId msgId) {
-  return MMR_CAN_IsMessageIdOfType(msgId, MMR_CAN_MESSAGE_ID_TYPE_SCS);
-}
-
-
 bool MMR_CAN_IsMessageIdOfType(
   MmrCanMessageId msgId,
   MmrCanMessageIdType type
diff --git a/Src/mmr_can_scs_manager.c b/Src/mmr_can_scs_manager.c
index f66df49..3f8c9bb 100644
--- a/Src/mmr_can_scs_manager.c
+++ b/Src/mmr_can_scs_manager.c
@@ -18,7 +18,7 @@ bool MMR_CAN_MaybeHandleAck(MmrCanHeader header) {
     return false;
   }
 
-  header.messageType = MMR_CAN_MESSAGE_TYPE_NORMAL;
+  header.messageType = MMR_CAN_MESSAGE_TYPE_SCS;
   MmrCanScsEntry *entry = findEntry(header);
   if (entry == NULL) {
     return false;
@@ -29,6 +29,15 @@ bool MMR_CAN_MaybeHandleAck(MmrCanHeader header) {
 }
 
 
+HalStatus MMR_CAN_SendAck(
+  CanHandle *hcan,
+  MmrCanHeader originalHeader
+) {
+  originalHeader.messageType = MMR_CAN_MESSAGE_TYPE_ACK;
+  return sendScs(hcan, originalHeader);
+}
+
+
 HalStatus MMR_CAN_SendScs(
   CanHandle *hcan,
   MmrCanMessageId scsId,
@@ -38,9 +47,13 @@ HalStatus MMR_CAN_SendScs(
     .senderId = senderId,
     .messageId = scsId,
     .priority = MMR_CAN_MESSAGE_PRIORITY_HIGH,
+	.messageType = MMR_CAN_MESSAGE_TYPE_SCS,
   };
 
-  putEntry(header);
+  if (putEntry(header) == NULL) {
+	return HAL_ERROR;
+  }
+
   return sendScs(hcan, header);
 }
 
@@ -68,7 +81,7 @@ HalStatus sendScs(CanHandle *hcan, MmrCanHeader header) {
     .length = 0,
   };
 
-  return MMR_CAN_Send(hcan, packet);
+  return MMR_CAN_SendNoTamper(hcan, packet);
 }
 
 
diff --git a/Src/mmr_can_send.c b/Src/mmr_can_send.c
index 2ff5374..d3ab377 100644
--- a/Src/mmr_can_send.c
+++ b/Src/mmr_can_send.c
@@ -36,14 +36,32 @@ HalStatus MMR_CAN_Send(CanHandle *hcan, MmrCanPacket packet) {
       .TransmitGlobalTime = DISABLE,
     },
   };
-  syncHeaders(&tp);
 
+  syncHeaders(&tp);
   return packet.length <= MMR_CAN_MAX_DATA_LENGTH
     ? sendNormal(&tp)
     : sendMulti(&tp);
 }
 
 
+HalStatus MMR_CAN_SendNoTamper(CanHandle *hcan, MmrCanPacket packet) {
+  TransmissionParams tp = {
+    .handle = hcan,
+    .packet = &packet,
+	.headers.mmr = packet.header,
+    .headers.tx = {
+      .IDE = CAN_ID_EXT,
+      .RTR = CAN_RTR_DATA,
+      .DLC = packet.length,
+      .TransmitGlobalTime = DISABLE,
+    },
+  };
+
+  syncHeaders(&tp);
+  return send(&tp);
+}
+
+
 static HalStatus sendNormal(TransmissionParams *tp) {
   setMessageType(tp, MMR_CAN_MESSAGE_TYPE_NORMAL);
   return send(tp);