diff --git a/yarn-project/aztec/src/cli/aztec_start_options.ts b/yarn-project/aztec/src/cli/aztec_start_options.ts
index 663734e3bbd..32c971638b1 100644
--- a/yarn-project/aztec/src/cli/aztec_start_options.ts
+++ b/yarn-project/aztec/src/cli/aztec_start_options.ts
@@ -8,6 +8,8 @@ import { proverNodeConfigMappings } from '@aztec/prover-node';
 import { allPxeConfigMappings } from '@aztec/pxe';
 import { telemetryClientConfigMappings } from '@aztec/telemetry-client/start';
 
+import { defaultMnemonic } from '../sandbox.js';
+
 // Define an interface for options
 export interface AztecStartOption {
   flag: string;
@@ -89,14 +91,14 @@ export const aztecStartOptions: { [key: string]: AztecStartOption[] } = {
     {
       flag: '--l1-chain-id <value>',
       description: 'The L1 chain ID',
-      defaultValue: 1337,
+      defaultValue: 31337,
       envVar: 'L1_CHAIN_ID',
       parseVal: val => parseInt(val, 10),
     },
     {
       flag: '--l1-mnemonic <value>',
       description: 'Mnemonic for L1 accounts. Will be used if no publisher private keys are provided',
-      defaultValue: undefined,
+      defaultValue: defaultMnemonic,
       envVar: 'MNEMONIC',
     },
   ],
diff --git a/yarn-project/aztec/src/cli/cmds/start_node.ts b/yarn-project/aztec/src/cli/cmds/start_node.ts
index a3666539abb..0f7693cb983 100644
--- a/yarn-project/aztec/src/cli/cmds/start_node.ts
+++ b/yarn-project/aztec/src/cli/cmds/start_node.ts
@@ -1,5 +1,6 @@
 import { aztecNodeConfigMappings, createAztecNodeRpcServer } from '@aztec/aztec-node';
 import { type PXE } from '@aztec/circuit-types';
+import { NULL_KEY } from '@aztec/ethereum';
 import { type ServerList } from '@aztec/foundation/json-rpc/server';
 import { type LogFn } from '@aztec/foundation/log';
 import { createProvingJobSourceServer } from '@aztec/prover-client/prover-agent';
@@ -40,7 +41,7 @@ export const startNode = async (
   }
 
   // Deploy contracts if needed
-  if (options.deployAztecContracts) {
+  if (nodeSpecificOptions.deployAztecContracts) {
     let account;
     if (nodeSpecificOptions.publisherPrivateKey) {
       account = privateKeyToAccount(nodeSpecificOptions.publisherPrivateKey);
@@ -68,7 +69,7 @@ export const startNode = async (
   } else {
     const sequencerConfig = extractNamespacedOptions(options, 'sequencer');
     let account;
-    if (!sequencerConfig.publisherPrivateKey) {
+    if (!sequencerConfig.publisherPrivateKey || sequencerConfig.publisherPrivateKey === NULL_KEY) {
       if (!options.l1Mnemonic) {
         userLog(
           '--sequencer.publisherPrivateKey or --l1-mnemonic is required to start Aztec Node with --sequencer option',