diff --git a/simulators/ethereum/engine/clmock.go b/simulators/ethereum/engine/clmock.go
index bbd8f574b8..0e53d2fc81 100644
--- a/simulators/ethereum/engine/clmock.go
+++ b/simulators/ethereum/engine/clmock.go
@@ -127,7 +127,6 @@ func (cl *CLMocker) setTTDBlockClient(ec *EngineClient) {
 	if td == nil {
 		cl.Fatalf("CLMocker: Returned TotalDifficultyHeader is invalid: %v", td)
 	}
-	cl.Logf("CLMocker: Returned TotalDifficultyHeader: %v", td)
 
 	if td.TotalDifficulty.ToInt().Cmp(ec.TerminalTotalDifficulty) < 0 {
 		cl.Fatalf("CLMocker: Attempted to set TTD Block when TTD had not been reached: %v > %v", ec.TerminalTotalDifficulty, td.TotalDifficulty.ToInt())
@@ -173,9 +172,9 @@ func (cl *CLMocker) setTTDBlockClient(ec *EngineClient) {
 // This method waits for TTD in at least one of the clients, then sends the
 // initial forkchoiceUpdated with the info obtained from the client.
 func (cl *CLMocker) waitForTTD() {
-	ec := cl.EngineClients.waitForTTD(cl.Timeout)
-	if ec == nil {
-		cl.Fatalf("CLMocker: Timeout while waiting for TTD")
+	ec, err := cl.EngineClients.waitForTTD(cl.Timeout)
+	if ec == nil || err != nil {
+		cl.Fatalf("CLMocker: Error while waiting for TTD: %v", err)
 	}
 	// One of the clients has reached TTD, send the initial fcU with this client as head
 	cl.setTTDBlockClient(ec)
diff --git a/simulators/ethereum/engine/engineclient.go b/simulators/ethereum/engine/engineclient.go
index 423144381b..204c965560 100644
--- a/simulators/ethereum/engine/engineclient.go
+++ b/simulators/ethereum/engine/engineclient.go
@@ -80,23 +80,35 @@ func (ec *EngineClient) Equals(ec2 *EngineClient) bool {
 	return ec.Container == ec2.Container
 }
 
-func (ec *EngineClient) checkTTD() bool {
+func (ec *EngineClient) checkTTD() (bool, error) {
 	var td *TotalDifficultyHeader
 	if err := ec.cEth.CallContext(ec.Ctx(), &td, "eth_getBlockByNumber", "latest", false); err != nil {
-		panic(err)
+		return false, err
 	}
-	return td.TotalDifficulty.ToInt().Cmp(ec.TerminalTotalDifficulty) >= 0
+	return td.TotalDifficulty.ToInt().Cmp(ec.TerminalTotalDifficulty) >= 0, nil
+}
+
+type WaitTTDResponse struct {
+	ec  *EngineClient
+	err error
 }
 
 // Wait until the TTD is reached by a single client.
-func (ec *EngineClient) waitForTTD(wg *sync.WaitGroup, done chan<- *EngineClient, cancel <-chan interface{}) {
+func (ec *EngineClient) waitForTTD(wg *sync.WaitGroup, done chan<- WaitTTDResponse, cancel <-chan interface{}) {
 	defer wg.Done()
 	for {
 		select {
 		case <-time.After(tTDCheckPeriod):
-			if ec.checkTTD() {
+			ttdReached, err := ec.checkTTD()
+			if err != nil {
+
+			}
+			if err != nil || ttdReached {
 				select {
-				case done <- ec:
+				case done <- WaitTTDResponse{
+					ec:  ec,
+					err: err,
+				}:
 				case <-cancel:
 				}
 				return
@@ -109,24 +121,28 @@ func (ec *EngineClient) waitForTTD(wg *sync.WaitGroup, done chan<- *EngineClient
 
 // Wait until the TTD is reached by a single client with a timeout.
 // Returns true if the TTD has been reached, false when timeout occurred.
-func (ec *EngineClient) waitForTTDWithTimeout(timeout <-chan time.Time) bool {
+func (ec *EngineClient) waitForTTDWithTimeout(timeout <-chan time.Time) error {
 	for {
 		select {
 		case <-time.After(tTDCheckPeriod):
-			if ec.checkTTD() {
-				return true
+			ttdReached, err := ec.checkTTD()
+			if err != nil {
+				return err
+			}
+			if ttdReached {
+				return nil
 			}
 		case <-timeout:
-			return false
+			return fmt.Errorf("Timeout")
 		}
 	}
 }
 
 // Wait until the TTD is reached by any of the engine clients
-func (ecs EngineClients) waitForTTD(timeout <-chan time.Time) *EngineClient {
+func (ecs EngineClients) waitForTTD(timeout <-chan time.Time) (*EngineClient, error) {
 	var wg sync.WaitGroup
 	defer wg.Wait()
-	done := make(chan *EngineClient)
+	done := make(chan WaitTTDResponse)
 	cancel := make(chan interface{})
 	defer close(cancel)
 	for _, ec := range ecs {
@@ -134,10 +150,10 @@ func (ecs EngineClients) waitForTTD(timeout <-chan time.Time) *EngineClient {
 		go ec.waitForTTD(&wg, done, cancel)
 	}
 	select {
-	case ec := <-done:
-		return ec
+	case r := <-done:
+		return r.ec, r.err
 	case <-timeout:
-		return nil
+		return nil, fmt.Errorf("Timeout")
 	}
 }
 
diff --git a/simulators/ethereum/engine/enginetests.go b/simulators/ethereum/engine/enginetests.go
index 80cd9d1bd9..c29f9b6471 100644
--- a/simulators/ethereum/engine/enginetests.go
+++ b/simulators/ethereum/engine/enginetests.go
@@ -259,12 +259,15 @@ var engineTests = []TestSpec{
 		SlotsToFinalized: big.NewInt(20),
 		Run:              invalidMissingAncestorReOrgGenSync(8, InvalidReceiptsRoot, false),
 	},
-	{
-		Name:             "Invalid Ancestor Chain Re-Org, Invalid Number, Invalid P9', Reveal using sync",
-		TimeoutSeconds:   30,
-		SlotsToFinalized: big.NewInt(20),
-		Run:              invalidMissingAncestorReOrgGenSync(9, InvalidNumber, false),
-	},
+	/*
+		TODO, RE-ENABLE: Test is causing a panic on the secondary node, disabling for now.
+		{
+			Name:             "Invalid Ancestor Chain Re-Org, Invalid Number, Invalid P9', Reveal using sync",
+			TimeoutSeconds:   30,
+			SlotsToFinalized: big.NewInt(20),
+			Run:              invalidMissingAncestorReOrgGenSync(9, InvalidNumber, false),
+		},
+	*/
 	{
 		Name:             "Invalid Ancestor Chain Re-Org, Invalid GasLimit, Invalid P9', Reveal using sync",
 		TimeoutSeconds:   30,
@@ -283,12 +286,15 @@ var engineTests = []TestSpec{
 		SlotsToFinalized: big.NewInt(20),
 		Run:              invalidMissingAncestorReOrgGenSync(8, InvalidTimestamp, false),
 	},
-	{
-		Name:             "Invalid Ancestor Chain Re-Org, Invalid PrevRandao, Invalid P9', Reveal using sync",
-		TimeoutSeconds:   30,
-		SlotsToFinalized: big.NewInt(20),
-		Run:              invalidMissingAncestorReOrgGenSync(8, InvalidPrevRandao, false),
-	},
+	/*
+		TODO, RE-ENABLE: Test consistently fails with Failed to set invalid block: missing trie node.
+		{
+			Name:             "Invalid Ancestor Chain Re-Org, Invalid PrevRandao, Invalid P9', Reveal using sync",
+			TimeoutSeconds:   30,
+			SlotsToFinalized: big.NewInt(20),
+			Run:              invalidMissingAncestorReOrgGenSync(8, InvalidPrevRandao, false),
+		},
+	*/
 	{
 		Name:             "Invalid Ancestor Chain Re-Org, Incomplete Transactions, Invalid P9', Reveal using sync",
 		TimeoutSeconds:   30,
@@ -1248,6 +1254,13 @@ func invalidMissingAncestorReOrgGenSync(invalid_index int, payloadField InvalidP
 		genesis := loadGenesis("init/genesis.json")
 		genesis.Config.TerminalTotalDifficulty = t.Engine.TerminalTotalDifficulty
 		secondaryClient, err := newNode(enode, &genesis)
+		defer func() {
+			if err := secondaryClient.Stop(); err != nil {
+				t.Logf("WARN (%s): Unable to stop secondary node: %v", t.TestName, err)
+			} else {
+				t.Logf("INFO (%s): Successfully stopped secondary node", t.TestName)
+			}
+		}()
 		if err != nil {
 			t.Fatalf("FAIL (%s): Unable to spawn a secondary client: %v", t.TestName, err)
 		}
@@ -1332,10 +1345,10 @@ func invalidMissingAncestorReOrgGenSync(invalid_index int, payloadField InvalidP
 					if i < invalid_index {
 						status, err := secondaryClient.sendNewPayload(altChainPayloads[i])
 						if err != nil {
-							t.Fatalf("FAIL (%s): Unable to send new payload: %v", t.TestName, err)
+							t.Fatalf("FAIL (%s): TEST ISSUE - Unable to send new payload: %v", t.TestName, err)
 						}
 						if status.Status != "VALID" && status.Status != "ACCEPTED" {
-							t.Fatalf("FAIL (%s): Invalid payload status, expected VALID, ACCEPTED: %v", t.TestName, status.Status)
+							t.Fatalf("FAIL (%s): TEST ISSUE - Invalid payload status, expected VALID, ACCEPTED: %v", t.TestName, status.Status)
 						}
 
 						status2, err := secondaryClient.sendFCU(&ForkchoiceStateV1{
@@ -1344,20 +1357,20 @@ func invalidMissingAncestorReOrgGenSync(invalid_index int, payloadField InvalidP
 							FinalizedBlockHash: cA.BlockHash,
 						}, nil)
 						if err != nil {
-							t.Fatalf("FAIL (%s): Unable to send new payload: %v", t.TestName, err)
+							t.Fatalf("FAIL (%s): TEST ISSUE - Unable to send new payload: %v", t.TestName, err)
 						}
 						if status2.PayloadStatus.Status != "VALID" && status2.PayloadStatus.Status != "SYNCING" {
-							t.Fatalf("FAIL (%s): Invalid payload status, expected VALID: %v", t.TestName, status2.PayloadStatus.Status)
+							t.Fatalf("FAIL (%s): TEST ISSUE - Invalid payload status, expected VALID: %v", t.TestName, status2.PayloadStatus.Status)
 						}
 
 					} else {
 						invalid_block, err := beacon.ExecutableDataToBlock(execData(altChainPayloads[i]))
 						if err != nil {
-							t.Fatalf("FAIL (%s): Failed to create block from payload: %v", t.TestName, err)
+							t.Fatalf("FAIL (%s): TEST ISSUE - Failed to create block from payload: %v", t.TestName, err)
 						}
 
 						if err := secondaryClient.setBlock(invalid_block, altChainPayloads[i-1].Number, altChainPayloads[i-1].StateRoot); err != nil {
-							t.Fatalf("FAIL (%s): Failed to set invalid block: %v", t.TestName, err)
+							t.Fatalf("FAIL (%s): TEST ISSUE - Failed to set invalid block: %v", t.TestName, err)
 						}
 						t.Logf("INFO (%s): Invalid block successfully set %d (%s): %v", t.TestName, i, payloadValidStr, altChainPayloads[i].BlockHash)
 					}
@@ -1365,9 +1378,9 @@ func invalidMissingAncestorReOrgGenSync(invalid_index int, payloadField InvalidP
 				// Check that the second node has the correct head
 				head := secondaryClient.eth.APIBackend.CurrentBlock()
 				if head.Hash() != altChainPayloads[n-1].BlockHash {
-					t.Fatalf("Secondary Node has invalid blockhash got %v want %v gotNum %v wantNum %v", head.Hash(), altChainPayloads[n-1].BlockHash, head.Number(), altChainPayloads[n].Number)
+					t.Fatalf("FAIL (%s): TEST ISSUE - Secondary Node has invalid blockhash got %v want %v gotNum %v wantNum %v", t.TestName, head.Hash(), altChainPayloads[n-1].BlockHash, head.Number(), altChainPayloads[n].Number)
 				} else {
-					t.Logf("Secondary Node has correct block")
+					t.Logf("INFO (%s): Secondary Node has correct block", t.TestName)
 				}
 
 				// If we are syncing through p2p, we need to keep polling until the client syncs the missing payloads
diff --git a/simulators/ethereum/engine/main.go b/simulators/ethereum/engine/main.go
index b1ed9035f1..6acb97bc18 100644
--- a/simulators/ethereum/engine/main.go
+++ b/simulators/ethereum/engine/main.go
@@ -137,6 +137,10 @@ have reached the Terminal Total Difficulty.`[1:],
 			Parameters:  newParams,
 			Files:       testFiles,
 			Run: func(t *hivesim.T, c *hivesim.Client) {
+				t.Logf("Start test: %s", currentTest.Name)
+				defer func() {
+					t.Logf("End test: %s", currentTest.Name)
+				}()
 				timeout := DefaultTestCaseTimeout
 				// If a TestSpec specifies a timeout, use that instead
 				if currentTest.TimeoutSeconds != 0 {
diff --git a/simulators/ethereum/engine/mergetests.go b/simulators/ethereum/engine/mergetests.go
index 1d5949360f..2471cb82d7 100644
--- a/simulators/ethereum/engine/mergetests.go
+++ b/simulators/ethereum/engine/mergetests.go
@@ -372,8 +372,8 @@ func GenerateMergeTestSpec(mergeTestSpec MergeTestSpec) TestSpec {
 	runFunc := func(t *TestEnv) {
 		// The first client waits for TTD, which ideally should be reached immediately using loaded chain
 		if !mergeTestSpec.SkipMainClientTTDWait {
-			if !t.Engine.waitForTTDWithTimeout(t.Timeout) {
-				t.Fatalf("FAIL (%s): Timeout waiting for EngineClient (%s) to reach TTD", t.TestName, t.Engine.Container)
+			if err := t.Engine.waitForTTDWithTimeout(t.Timeout); err != nil {
+				t.Fatalf("FAIL (%s): Error while waiting for EngineClient (%s) to reach TTD: %v", t.TestName, t.Engine.Container, err)
 			}
 
 			if !mergeTestSpec.SkipMainClientFcU {
@@ -411,8 +411,8 @@ func GenerateMergeTestSpec(mergeTestSpec MergeTestSpec) TestSpec {
 			t.CLMock.AddEngineClient(t.T, secondaryClient.Client, big.NewInt(secondaryClientSpec.TTD))
 
 			if secondaryClientSpec.BuildPoSChainOnTop {
-				if !secondaryClient.waitForTTDWithTimeout(t.Timeout) {
-					t.Fatalf("FAIL (%s): Timeout waiting for EngineClient (%s) to reach TTD", t.TestName, secondaryClient.Client.Container)
+				if err := secondaryClient.waitForTTDWithTimeout(t.Timeout); err != nil {
+					t.Fatalf("FAIL (%s): Error while waiting for EngineClient (%s) to reach TTD: %v", t.TestName, secondaryClient.Client.Container, err)
 				}
 				t.CLMock.setTTDBlockClient(secondaryClient)
 			}
diff --git a/simulators/ethereum/engine/node.go b/simulators/ethereum/engine/node.go
index 8b642fbf47..9e69bb727a 100644
--- a/simulators/ethereum/engine/node.go
+++ b/simulators/ethereum/engine/node.go
@@ -98,6 +98,10 @@ func restart(bootnode, datadir string, genesis *core.Genesis) (*gethNode, error)
 	}, err
 }
 
+func (n *gethNode) Stop() error {
+	return n.eth.Stop()
+}
+
 type validator struct{}
 
 func (v *validator) ValidateBody(block *types.Block) error {
diff --git a/simulators/ethereum/engine/testenv.go b/simulators/ethereum/engine/testenv.go
index f753e79f69..630d1d1f6b 100644
--- a/simulators/ethereum/engine/testenv.go
+++ b/simulators/ethereum/engine/testenv.go
@@ -143,21 +143,21 @@ func (t *TestEnv) StartClient(clientType string, params hivesim.Params, ttd *big
 func (t *TestEnv) makeNextTransaction(recipient common.Address, amount *big.Int, payload []byte) *types.Transaction {
 
 	gasLimit := uint64(75000)
-
 	tx := types.NewTransaction(t.nonce, recipient, amount, gasLimit, gasPrice, payload)
 	signer := types.NewEIP155Signer(chainID)
 	signedTx, err := types.SignTx(tx, signer, vaultKey)
 	if err != nil {
 		t.Fatal("FAIL (%s): could not sign new tx: %v", t.TestName, err)
 	}
+	t.Logf("INFO (%s): Built next transaction: hash=%s, nonce=%d, recipient=%s", t.TestName, signedTx.Hash(), t.nonce, recipient)
 	t.nonce++
 	return signedTx
 }
 
-func (t *TestEnv) sendNextTransaction(sender *EngineClient, recipient common.Address, amount *big.Int, payload []byte) *types.Transaction {
+func (t *TestEnv) sendNextTransaction(node *EngineClient, recipient common.Address, amount *big.Int, payload []byte) *types.Transaction {
 	tx := t.makeNextTransaction(recipient, amount, payload)
 	for {
-		err := sender.Eth.SendTransaction(sender.Ctx(), tx)
+		err := node.Eth.SendTransaction(node.Ctx(), tx)
 		if err == nil {
 			return tx
 		}