diff --git a/Core/Src/yunhorn_sts_process.c b/Core/Src/yunhorn_sts_process.c
index 6e5528a..05cbb7d 100644
--- a/Core/Src/yunhorn_sts_process.c
+++ b/Core/Src/yunhorn_sts_process.c
@@ -129,7 +129,7 @@ extern volatile uint8_t sensor_data_ready;
 
 void STS_YunhornAuthenticationCode_Process(void)
 {
-	if (sts_ac_code[0] == 0x00) {
+	if ((sts_ac_code[0] == 0x00) && (sts_ac_code[19] == 0x00)) {
 		APP_LOG(TS_OFF,VLEVEL_M, "Initial AC CODE blank... \r\n");
 		return;
 	}