diff --git a/packages/contracts-bedrock/test/L1/L1StandardBridge.t.sol b/packages/contracts-bedrock/test/L1/L1StandardBridge.t.sol
index a876ef795f7..abec06bf78b 100644
--- a/packages/contracts-bedrock/test/L1/L1StandardBridge.t.sol
+++ b/packages/contracts-bedrock/test/L1/L1StandardBridge.t.sol
@@ -376,6 +376,20 @@ contract L1StandardBridge_Receive_Test is CommonTest {
         (bool revertsAsExpected,) = address(l1StandardBridge).call{ value: 100 }(hex"");
         assertTrue(revertsAsExpected, "expectRevert: call did not revert");
     }
+
+    /// @notice Tests that receive reverts when custom gas token is enabled and value is sent.
+    function testFuzz_receive_withCustomGasToken_reverts(uint256 _value) external {
+        skipIfSysFeatureDisabled(Features.CUSTOM_GAS_TOKEN);
+
+        _value = bound(_value, 1, type(uint128).max);
+        vm.deal(alice, _value);
+
+        vm.prank(alice, alice);
+        vm.expectRevert(IOptimismPortal2.OptimismPortal_NotAllowedOnCGTMode.selector);
+
+        (bool revertsAsExpected,) = address(l1StandardBridge).call{ value: _value }(hex"");
+        assertTrue(revertsAsExpected, "expectRevert: call did not revert");
+    }
 }
 
 /// @title L1StandardBridge_DepositETH_Test
@@ -427,6 +441,32 @@ contract L1StandardBridge_DepositETH_Test is L1StandardBridge_TestInit {
         vm.prank(alice);
         l1StandardBridge.depositETH{ value: 1 }(300, hex"");
     }
+
+    /// @notice Tests that depositETH reverts when custom gas token is enabled and value is sent.
+    function testFuzz_depositETH_withCustomGasToken_reverts(uint256 _value, uint32 _minGasLimit) external {
+        skipIfSysFeatureDisabled(Features.CUSTOM_GAS_TOKEN);
+
+        _value = bound(_value, 1, type(uint128).max);
+        vm.deal(alice, _value);
+
+        vm.prank(alice, alice);
+        vm.expectRevert(IOptimismPortal2.OptimismPortal_NotAllowedOnCGTMode.selector);
+        l1StandardBridge.depositETH{ value: _value }(_minGasLimit, hex"dead");
+    }
+
+    /// @notice Tests that depositETH reverts when custom gas token is enabled for EOA with 7702 delegation.
+    function testFuzz_depositETH_fromEOA7702WithCustomGasToken_reverts(uint256 _value, uint32 _minGasLimit) external {
+        skipIfSysFeatureDisabled(Features.CUSTOM_GAS_TOKEN);
+        _value = bound(_value, 1, type(uint128).max);
+
+        // Set alice to have 7702 code.
+        vm.etch(alice, abi.encodePacked(hex"EF0100", address(0)));
+
+        vm.deal(alice, _value);
+        vm.prank(alice, alice);
+        vm.expectRevert(IOptimismPortal2.OptimismPortal_NotAllowedOnCGTMode.selector);
+        l1StandardBridge.depositETH{ value: _value }(_minGasLimit, hex"dead");
+    }
 }
 
 /// @title L1StandardBridge_DepositETHTo_Test
@@ -474,6 +514,23 @@ contract L1StandardBridge_DepositETHTo_Test is L1StandardBridge_TestInit {
             assertEq(address(optimismPortal2).balance, portalBalanceBefore + _amount);
         }
     }
+
+    /// @notice Tests that depositETHTo reverts when custom gas token is enabled and value is sent.
+    function testFuzz_depositETHTo_withCustomGasToken_reverts(
+        address _to,
+        uint256 _value,
+        uint32 _minGasLimit
+    )
+        external
+    {
+        skipIfSysFeatureDisabled(Features.CUSTOM_GAS_TOKEN);
+        vm.assume(_to != address(0));
+        _value = bound(_value, 1, type(uint128).max);
+        vm.deal(alice, _value);
+        vm.prank(alice);
+        vm.expectRevert(IOptimismPortal2.OptimismPortal_NotAllowedOnCGTMode.selector);
+        l1StandardBridge.depositETHTo{ value: _value }(_to, _minGasLimit, hex"dead");
+    }
 }
 
 /// @title L1StandardBridge_DepositERC20_Test
@@ -877,4 +934,35 @@ contract L1StandardBridge_Uncategorized_Test is L1StandardBridge_TestInit {
         vm.expectRevert("StandardBridge: cannot send to messenger");
         l1StandardBridge.finalizeBridgeETH{ value: 100 }(alice, messenger, 100, hex"");
     }
+
+    /// @notice Tests that bridgeETH reverts when custom gas token is enabled and value is sent.
+    function testFuzz_bridgeETH_withCustomGasToken_reverts(uint256 _value, uint32 _minGasLimit) external {
+        skipIfSysFeatureDisabled(Features.CUSTOM_GAS_TOKEN);
+
+        _value = bound(_value, 1, type(uint128).max);
+        vm.deal(alice, _value);
+
+        vm.prank(alice, alice);
+        vm.expectRevert(IOptimismPortal2.OptimismPortal_NotAllowedOnCGTMode.selector);
+        l1StandardBridge.bridgeETH{ value: _value }(_minGasLimit, hex"dead");
+    }
+
+    /// @notice Tests that bridgeETHTo reverts when custom gas token is enabled and value is sent.
+    function testFuzz_bridgeETHTo_withCustomGasToken_reverts(
+        address _to,
+        uint256 _value,
+        uint32 _minGasLimit
+    )
+        external
+    {
+        skipIfSysFeatureDisabled(Features.CUSTOM_GAS_TOKEN);
+
+        vm.assume(_to != address(0));
+        _value = bound(_value, 1, type(uint128).max);
+        vm.deal(alice, _value);
+
+        vm.prank(alice);
+        vm.expectRevert(IOptimismPortal2.OptimismPortal_NotAllowedOnCGTMode.selector);
+        l1StandardBridge.bridgeETHTo{ value: _value }(_to, _minGasLimit, hex"dead");
+    }
 }
diff --git a/packages/contracts-bedrock/test/L2/FeeVault.t.sol b/packages/contracts-bedrock/test/L2/FeeVault.t.sol
index 56898a5a356..aa8a572335b 100644
--- a/packages/contracts-bedrock/test/L2/FeeVault.t.sol
+++ b/packages/contracts-bedrock/test/L2/FeeVault.t.sol
@@ -8,6 +8,7 @@ import { CommonTest } from "test/setup/CommonTest.sol";
 import { IProxyAdmin } from "interfaces/universal/IProxyAdmin.sol";
 import { IFeeVault } from "interfaces/L2/IFeeVault.sol";
 import { IL2ToL1MessagePasser } from "interfaces/L2/IL2ToL1MessagePasser.sol";
+import { IL2ToL1MessagePasserCGT } from "interfaces/L2/IL2ToL1MessagePasserCGT.sol";
 
 // Libraries
 import { Hashing } from "src/libraries/Hashing.sol";
@@ -145,6 +146,31 @@ abstract contract FeeVault_Uncategorized_Test is CommonTest {
         assertEq(Predeploys.L2_TO_L1_MESSAGE_PASSER.balance, amount);
     }
 
+    /// @notice Tests that withdraw to L1 reverts when custom gas token is enabled and value is sent.
+    function testFuzz_withdraw_toL1WithCustomGasToken_reverts(uint256 _amount) external {
+        skipIfSysFeatureDisabled(Features.CUSTOM_GAS_TOKEN);
+
+        // Setup L1 withdrawal
+        vm.prank(IProxyAdmin(Predeploys.PROXY_ADMIN).owner());
+        feeVault.setWithdrawalNetwork(Types.WithdrawalNetwork.L1);
+
+        // Set recipient
+        vm.prank(IProxyAdmin(Predeploys.PROXY_ADMIN).owner());
+        feeVault.setRecipient(recipient);
+
+        // Set minimum withdrawal amount
+        vm.prank(IProxyAdmin(Predeploys.PROXY_ADMIN).owner());
+        feeVault.setMinWithdrawalAmount(minWithdrawalAmount);
+
+        // Set the balance to be greater than the minimum withdrawal amount
+        _amount = bound(_amount, feeVault.minWithdrawalAmount() + 1, type(uint128).max);
+        vm.deal(address(feeVault), _amount);
+
+        // Withdrawal should revert due to CGT mode
+        vm.expectRevert(IL2ToL1MessagePasserCGT.L2ToL1MessagePasserCGT_NotAllowedOnCGTMode.selector);
+        feeVault.withdraw();
+    }
+
     /// @notice Tests that `withdraw` successfully initiates a withdrawal to L2.
     function test_withdraw_toL2_succeeds() public {
         _setupL2Withdrawal();
diff --git a/packages/contracts-bedrock/test/L2/L2StandardBridge.t.sol b/packages/contracts-bedrock/test/L2/L2StandardBridge.t.sol
index 8df5b33b4fa..a0f1c0aec8c 100644
--- a/packages/contracts-bedrock/test/L2/L2StandardBridge.t.sol
+++ b/packages/contracts-bedrock/test/L2/L2StandardBridge.t.sol
@@ -20,6 +20,7 @@ import { Features } from "src/libraries/Features.sol";
 import { ICrossDomainMessenger } from "interfaces/universal/ICrossDomainMessenger.sol";
 import { IStandardBridge } from "interfaces/universal/IStandardBridge.sol";
 import { IL2ToL1MessagePasser } from "interfaces/L2/IL2ToL1MessagePasser.sol";
+import { IL2ToL1MessagePasserCGT } from "interfaces/L2/IL2ToL1MessagePasserCGT.sol";
 import { IL2StandardBridge } from "interfaces/L2/IL2StandardBridge.sol";
 
 /// @title L2StandardBridge_TestInit
@@ -299,6 +300,20 @@ contract L2StandardBridge_Receive_Test is L2StandardBridge_TestInit {
         assertEq(success, true);
         assertEq(address(l2ToL1MessagePasser).balance, 100);
     }
+
+    /// @notice Tests that receive reverts when custom gas token is enabled and value is sent.
+    function testFuzz_receive_withCustomGasToken_reverts(uint256 _value) external {
+        skipIfSysFeatureDisabled(Features.CUSTOM_GAS_TOKEN);
+
+        _value = bound(_value, 1, type(uint128).max);
+        vm.deal(alice, _value);
+
+        vm.prank(alice, alice);
+        vm.expectRevert(IL2ToL1MessagePasserCGT.L2ToL1MessagePasserCGT_NotAllowedOnCGTMode.selector);
+
+        (bool revertsAsExpected,) = address(l2StandardBridge).call{ value: _value }(hex"");
+        assertTrue(revertsAsExpected, "expectRevert: call did not revert");
+    }
 }
 
 /// @title L2StandardBridge_Withdraw_Test
@@ -376,6 +391,18 @@ contract L2StandardBridge_Withdraw_Test is L2StandardBridge_TestInit {
         vm.expectRevert("StandardBridge: function can only be called from an EOA");
         l2StandardBridge.withdraw(address(L2Token), 100, 1000, hex"");
     }
+
+    /// @notice Tests that withdraw reverts when custom gas token is enabled and value is sent.
+    function testFuzz_withdraw_withCustomGasToken_reverts(uint256 _value, uint32 _minGasLimit) external {
+        skipIfSysFeatureDisabled(Features.CUSTOM_GAS_TOKEN);
+
+        _value = bound(_value, 1, type(uint128).max);
+        vm.deal(alice, _value);
+
+        vm.prank(alice, alice);
+        vm.expectRevert(IL2ToL1MessagePasserCGT.L2ToL1MessagePasserCGT_NotAllowedOnCGTMode.selector);
+        l2StandardBridge.withdraw{ value: _value }(Predeploys.LEGACY_ERC20_ETH, _value, _minGasLimit, hex"");
+    }
 }
 
 /// @title L2StandardBridge_WithdrawTo_Test
@@ -595,4 +622,42 @@ contract L2StandardBridge_Uncategorized_Test is L2StandardBridge_TestInit {
         vm.expectRevert("StandardBridge: wrong remote token for Optimism Mintable ERC20 local token");
         l2StandardBridge.finalizeBridgeERC20(localToken, remoteToken, alice, alice, 100, hex"");
     }
+
+    /// @notice Tests that bridgeETH reverts when custom gas token is enabled and value is sent.
+    function testFuzz_bridgeETH_withCustomGasToken_reverts(
+        uint256 _value,
+        uint32 _minGasLimit,
+        bytes calldata _extraData
+    )
+        external
+    {
+        skipIfSysFeatureDisabled(Features.CUSTOM_GAS_TOKEN);
+
+        _value = bound(_value, 1, type(uint128).max);
+        vm.deal(alice, _value);
+
+        vm.prank(alice, alice);
+        vm.expectRevert(IL2ToL1MessagePasserCGT.L2ToL1MessagePasserCGT_NotAllowedOnCGTMode.selector);
+        l2StandardBridge.bridgeETH{ value: _value }(_minGasLimit, _extraData);
+    }
+
+    /// @notice Tests that bridgeETHTo reverts when custom gas token is enabled and value is sent.
+    function testFuzz_bridgeETHTo_withCustomGasToken_reverts(
+        address _to,
+        uint256 _value,
+        uint32 _minGasLimit,
+        bytes calldata _extraData
+    )
+        external
+    {
+        skipIfSysFeatureDisabled(Features.CUSTOM_GAS_TOKEN);
+
+        vm.assume(_to != address(0));
+        _value = bound(_value, 1, type(uint128).max);
+        vm.deal(alice, _value);
+
+        vm.prank(alice, alice);
+        vm.expectRevert(IL2ToL1MessagePasserCGT.L2ToL1MessagePasserCGT_NotAllowedOnCGTMode.selector);
+        l2StandardBridge.bridgeETHTo{ value: _value }(_to, _minGasLimit, _extraData);
+    }
 }