diff --git a/clash-cores/src/Clash/Cores/Sgmii/Common.hs b/clash-cores/src/Clash/Cores/Sgmii/Common.hs
index 27c12216f4..f4867f215a 100644
--- a/clash-cores/src/Clash/Cores/Sgmii/Common.hs
+++ b/clash-cores/src/Clash/Cores/Sgmii/Common.hs
@@ -5,24 +5,6 @@ import Clash.Prelude
 -- | Format of rxConfReg and txConfReg, size of two data words
 type ConfReg = BitVector 16
 
--- | Data type that contains a 'BitVector 10' with the corresponding error
---   condition of the encode function
-data CodeGroup
-  = Cg (BitVector 10)
-  | CgError (BitVector 10)
-  deriving (Generic, NFDataX, Eq, Show)
-
--- | Function to check whether a 'CodeGroup' results in a code group
-isCg :: CodeGroup -> Bool
-isCg (Cg _) = True
-isCg _ = False
-
--- | Function to convert a 'CodeGroup' to a plain 'BitVector 10'
-fromCg :: CodeGroup -> BitVector 10
-fromCg cg = case cg of
-  Cg _cg -> _cg
-  _ -> 0
-
 -- | Data type that contains a 'BitVector 8' with the corresponding error
 --   condition of the decode function
 data DataWord
diff --git a/clash-cores/src/Clash/Cores/Sgmii/EbTb.hs b/clash-cores/src/Clash/Cores/Sgmii/EbTb.hs
index 98d6362060..451a32018c 100644
--- a/clash-cores/src/Clash/Cores/Sgmii/EbTb.hs
+++ b/clash-cores/src/Clash/Cores/Sgmii/EbTb.hs
@@ -41,24 +41,17 @@ ebTbDecode rd cg = (rdNew, dw)
 {-# CLASH_OPAQUE ebTbDecode #-}
 
 -- | Take the running disparity and the current 'DataWord', and return a tuple
---   containing the new running disparity and a 'CodeGroup' containing the
+--   containing the new running disparity and a 'BitVector' containing the
 --   encoded value. This function uses a 'MemBlob' to store the encoder lookup
 --   table.
---
---   Remarks:
---   - I don't completely know yet if it is useful to have a specific type for
---     CodeGroup, as a codegroup is always connected to the outside world and
---     so it might be more relevant to have it a plain 'BitVector 10'.
---   - The same goes for whether it is relevant to return an error for an input
---     error, see the second case of 'ebTbEncode'.
 ebTbEncode ::
   -- | Running disparity
   Bool ->
   -- | Data word
   DataWord ->
-  -- | Tuple containing the new running disparity and the 'CodeGroup'
-  (Bool, CodeGroup)
-ebTbEncode rd (Dw dw) = (rdNew, Cg $ pack $ reverse cg)
+  -- | Tuple containing the new running disparity and the code group
+  (Bool, BitVector 10)
+ebTbEncode rd (Dw dw) = (rdNew, pack $ reverse cg)
  where
   (statusBits, cg) =
     splitAt d2
@@ -68,13 +61,9 @@ ebTbEncode rd (Dw dw) = (rdNew, Cg $ pack $ reverse cg)
       $ unpack (0 ++# bitCoerce rd ++# dw)
 
   rdNew = bitCoerce $ last statusBits
-ebTbEncode rd (Cw dw) = (rdNew, cg)
+ebTbEncode rd (Cw dw) = (rdNew, if cgEr then 0 else pack $ reverse cg)
  where
-  cg
-    | cgEr = CgError $ pack $ reverse _cg
-    | otherwise = Cg $ pack $ reverse _cg
-
-  (statusBits, _cg) =
+  (statusBits, cg) =
     splitAt d2
       $ bv2v
       $ asyncRomBlobPow2
@@ -83,6 +72,6 @@ ebTbEncode rd (Cw dw) = (rdNew, cg)
 
   cgEr = bitCoerce $ head statusBits
   rdNew = bitCoerce $ last statusBits
-ebTbEncode rd _ = (rd, CgError 0)
+ebTbEncode rd _ = (rd, 0)
 
 {-# CLASH_OPAQUE ebTbEncode #-}
diff --git a/clash-cores/src/Clash/Cores/Sgmii/PcsReceive.hs b/clash-cores/src/Clash/Cores/Sgmii/PcsReceive.hs
index 29324118af..c3de7d10ac 100644
--- a/clash-cores/src/Clash/Cores/Sgmii/PcsReceive.hs
+++ b/clash-cores/src/Clash/Cores/Sgmii/PcsReceive.hs
@@ -97,7 +97,7 @@ carrierDetect rd dw rxEven
   cgK28_5N = 0b0011111010
   cgK28_5P = 0b1100000101
   cgK28_5 = if rd then cgK28_5P else cgK28_5N
-  cg = fromCg $ snd $ ebTbEncode rd dw
+  cg = snd $ ebTbEncode rd dw
 
 -- | Take the running disparity, the current and next two input data words and
 --   check whether they correspond to one of the specified end conditions
diff --git a/clash-cores/src/Clash/Cores/Sgmii/PcsTransmit.hs b/clash-cores/src/Clash/Cores/Sgmii/PcsTransmit.hs
index 557b2c4b91..ab9cd2417e 100644
--- a/clash-cores/src/Clash/Cores/Sgmii/PcsTransmit.hs
+++ b/clash-cores/src/Clash/Cores/Sgmii/PcsTransmit.hs
@@ -12,11 +12,11 @@ pcsTransmit ::
   Signal dom (BitVector 8) ->
   Signal dom Xmit ->
   Signal dom ConfReg ->
-  Signal dom CodeGroup
+  Signal dom (BitVector 10)
 pcsTransmit txEn txEr dw xmit txConfReg = cg
  where
   (_, cg, txEven, cgSent) =
-    mealyB codeGroupT Init (txOSet, dw, txConfReg)
+    mealyB codeGroupT (SpecialGo False Even) (txOSet, dw, txConfReg)
 
   (_, txOSet) =
     mealyB
diff --git a/clash-cores/src/Clash/Cores/Sgmii/PcsTransmit/CodeGroup.hs b/clash-cores/src/Clash/Cores/Sgmii/PcsTransmit/CodeGroup.hs
index 36381ef699..7589de395e 100644
--- a/clash-cores/src/Clash/Cores/Sgmii/PcsTransmit/CodeGroup.hs
+++ b/clash-cores/src/Clash/Cores/Sgmii/PcsTransmit/CodeGroup.hs
@@ -7,8 +7,7 @@ import Clash.Cores.Sgmii.EbTb
 import Clash.Prelude
 
 data CodeGroupState
-  = Init
-  | SpecialGo {_rd :: Bool, _txEven :: Even}
+  = SpecialGo {_rd :: Bool, _txEven :: Even}
   | DataGo {_rd :: Bool, _txEven :: Even}
   | IdleDisparityWrong {_rd :: Bool}
   | IdleI1B {_rd :: Bool}
@@ -27,24 +26,7 @@ data CodeGroupState
 codeGroupT ::
   CodeGroupState ->
   (DataWord, BitVector 8, ConfReg) ->
-  (CodeGroupState, (CodeGroupState, CodeGroup, Even, Bool))
-codeGroupT self@Init (txOSet, _, _) = (nextState, out)
- where
-  nextState
-    | fromDw txOSet == dwV = SpecialGo rd txEven
-    | fromDw txOSet == dwS = SpecialGo rd txEven
-    | fromDw txOSet == dwT = SpecialGo rd txEven
-    | fromDw txOSet == dwR = SpecialGo rd txEven
-    | isDw txOSet = DataGo rd txEven
-    | fromDw txOSet == dwI && rd = IdleDisparityWrong rd
-    | fromDw txOSet == dwI && not rd = IdleDisparityOk rd
-    | fromDw txOSet == dwC = ConfigurationC1A rd
-    | otherwise = self
-
-  rd = False
-  txEven = Even
-
-  out = (self, Cg 0, txEven, False)
+  (CodeGroupState, (CodeGroupState, BitVector 10, Even, Bool))
 codeGroupT self@SpecialGo{..} (txOSet, _, _) = (nextState, out)
  where
   nextState
diff --git a/clash-cores/test/Test/Cores/Sgmii/EbTb.hs b/clash-cores/test/Test/Cores/Sgmii/EbTb.hs
index ba767d3680..ca72d7b3f0 100644
--- a/clash-cores/test/Test/Cores/Sgmii/EbTb.hs
+++ b/clash-cores/test/Test/Cores/Sgmii/EbTb.hs
@@ -18,8 +18,8 @@ prop_ebTbDecodeCheckNothing = H.property $ do
   inp <- H.forAll (Gen.filterT checkBitSequence genDefinedBitVector)
   let out = isValidDw dw1 && isValidDw dw2
        where
-        (_, dw1) = ebTbDecode False $ fromCg $ snd $ ebTbEncode False (Dw inp)
-        (_, dw2) = ebTbDecode True $ fromCg $ snd $ ebTbEncode True (Dw inp)
+        (_, dw1) = ebTbDecode False $ snd $ ebTbEncode False (Dw inp)
+        (_, dw2) = ebTbDecode True $ snd $ ebTbEncode True (Dw inp)
 
   H.assert out
 
@@ -28,7 +28,7 @@ prop_ebTbDecodeCheckNothing = H.property $ do
 prop_ebTbEncodeCheckNothing :: H.Property
 prop_ebTbEncodeCheckNothing = H.property $ do
   inp <- H.forAll genDefinedBitVector
-  let out = isCg $ snd $ ebTbEncode False (Dw inp)
+  let out = 0 /= snd (ebTbEncode False (Dw inp))
 
   H.assert out
 
@@ -42,11 +42,7 @@ prop_ebTbEncodeDecode = H.property $ do
   inp <- H.forAll genDefinedBitVector
   let out = if isValidDw dw then fromDw dw else inp
        where
-        cg = snd $ ebTbEncode False (Dw inp)
-
-        (_, dw) = case cg of
-          Cg _cg -> ebTbDecode False _cg
-          CgError _ -> (False, Dw inp)
+        dw = snd $ ebTbDecode False $ snd $ ebTbEncode False (Dw inp)
 
       expected = inp
 
@@ -67,10 +63,9 @@ prop_ebTbDecodeEncode = H.property $ do
        where
         o = g False inp
 
-        g rd i = fromCg cg
+        g rd i = if isValidDw dw then snd $ ebTbEncode rd dw else i
          where
           dw = snd $ ebTbDecode rd i
-          cg = if isValidDw dw then snd $ ebTbEncode rd dw else Cg i
 
       expected = inp