diff --git a/src/shared/key-management/aws/checker.ts b/src/shared/key-management/aws/checker.ts
index ff256d8..de22c64 100644
--- a/src/shared/key-management/aws/checker.ts
+++ b/src/shared/key-management/aws/checker.ts
@@ -57,25 +57,10 @@ export class AwsKeyChecker extends KeyCheckerBase<AwsBedrockKey> {
         this.invokeModel("anthropic.claude-3-sonnet-20240229-v1:0", key),
         this.invokeModel("anthropic.claude-3-haiku-20240307-v1:0", key),
         this.invokeModel("anthropic.claude-3-opus-20240229-v1:0", key),
+        this.invokeModel("anthropic.claude-3-5-sonnet-20240620-v1:0", key),
       ];
     }
 
-    // Sonnet 3.5 is being gradually rolled out and some AWS keys/regions throw
-    // a ResourceNotFoundException when trying to invoke it which will fail the
-    // entire key As a temporary measure we will trap thrown errors for this
-    // particular check and ignore them.
-    checks.push(
-      this.invokeModel("anthropic.claude-3-5-sonnet-20240620-v1:0", key).catch(
-        ({ response }) => {
-          this.log.debug(
-            { key: key.hash, error: response.data, status: response.status },
-            "AWS Sonnet 3.5 model is not accessible."
-          );
-          return false;
-        }
-      )
-    );
-
     checks.unshift(this.checkLoggingConfiguration(key));
 
     const [_logging, claudeV2, sonnet, haiku, opus, sonnet35] =
@@ -199,7 +184,7 @@ export class AwsKeyChecker extends KeyCheckerBase<AwsBedrockKey> {
       method: "POST",
       url: POST_INVOKE_MODEL_URL(creds.region, model),
       data: payload,
-      validateStatus: (status) => status === 400 || status === 403,
+      validateStatus: (status) => [400, 403, 404].includes(status),
     };
     config.headers = new AxiosHeaders({
       "content-type": "application/json",
@@ -218,6 +203,16 @@ export class AwsKeyChecker extends KeyCheckerBase<AwsBedrockKey> {
     ) {
       return false;
     }
+    
+    // ResourceNotFound typically indicates that the tested model cannot be used
+    // on the configured region for this set of credentials.
+    if (status === 404) {
+      this.log.debug(
+        { region: creds.region, model, key: key.hash },
+        "Model not supported in this AWS region."
+      );
+      return false;
+    }
 
     // We're looking for a specific error type and message here
     // "ValidationException"