diff --git a/packages/mongodb-memory-server-core/src/util/MongoInstance.ts b/packages/mongodb-memory-server-core/src/util/MongoInstance.ts
index 1d159b7a5..272f9c5d2 100644
--- a/packages/mongodb-memory-server-core/src/util/MongoInstance.ts
+++ b/packages/mongodb-memory-server-core/src/util/MongoInstance.ts
@@ -13,7 +13,12 @@ import {
 import { lt } from 'semver';
 import { EventEmitter } from 'events';
 import { MongoClient, MongoClientOptions, MongoNetworkError } from 'mongodb';
-import { KeyFileMissingError, StartBinaryFailedError, StdoutInstanceError } from './errors';
+import {
+  GenericMMSError,
+  KeyFileMissingError,
+  StartBinaryFailedError,
+  StdoutInstanceError,
+} from './errors';
 
 // ignore the nodejs warning for coverage
 /* istanbul ignore next */
@@ -327,6 +332,13 @@ export class MongoInstance extends EventEmitter implements ManagerBase {
    */
   async start(): Promise<void> {
     this.debug('start');
+
+    if (!isNullOrUndefined(this.mongodProcess?.pid)) {
+      throw new GenericMMSError(
+        `Cannot run "MongoInstance.start" because "mongodProcess.pid" is still defined (pid: ${this.mongodProcess?.pid})`
+      );
+    }
+
     this.isInstancePrimary = false;
     this.isInstanceReady = false;
     this.isReplSet = false;
diff --git a/packages/mongodb-memory-server-core/src/util/__tests__/MongoInstance.test.ts b/packages/mongodb-memory-server-core/src/util/__tests__/MongoInstance.test.ts
index 3a30e0bef..5be65f2e6 100644
--- a/packages/mongodb-memory-server-core/src/util/__tests__/MongoInstance.test.ts
+++ b/packages/mongodb-memory-server-core/src/util/__tests__/MongoInstance.test.ts
@@ -4,7 +4,7 @@ import * as dbUtil from '../utils';
 import MongodbInstance, { MongoInstanceEvents } from '../MongoInstance';
 import resolveConfig, { ResolveConfigVariables } from '../resolveConfig';
 import getPort from 'get-port';
-import { StartBinaryFailedError, StdoutInstanceError } from '../errors';
+import { GenericMMSError, StartBinaryFailedError, StdoutInstanceError } from '../errors';
 import { assertIsError } from '../../__tests__/testUtils/test_utils';
 
 jest.setTimeout(100000); // 10s
@@ -506,4 +506,28 @@ describe('MongodbInstance', () => {
       });
     });
   });
+
+  it('should throw error if instance is already started (#662)', async () => {
+    const gotPort = await getPort();
+    const mongod = await MongodbInstance.create({
+      instance: { port: gotPort, dbPath: tmpDir.name },
+      binary: { version },
+    });
+
+    try {
+      await mongod.start();
+
+      fail('Expected to Fail');
+    } catch (err) {
+      expect(err).toBeInstanceOf(GenericMMSError);
+      assertIsError(err); // has to be used, because there is not typeguard from "expect(variable).toBeInstanceOf"
+      expect(
+        err.message.includes(
+          'Cannot run "MongoInstance.start" because "mongodProcess.pid" is still defined'
+        )
+      ).toBeTruthy();
+    } finally {
+      await mongod.stop();
+    }
+  });
 });