diff --git a/Marlin/Marlin_main.cpp b/Marlin/Marlin_main.cpp
index c9257c20c..e822acd8b 100644
--- a/Marlin/Marlin_main.cpp
+++ b/Marlin/Marlin_main.cpp
@@ -4465,6 +4465,9 @@ inline void gcode_M303() {
   int c = code_seen('C') ? code_value_short() : 5;
   float temp = code_seen('S') ? code_value() : (e < 0 ? 70.0 : 150.0);
   PID_autotune(temp, e, c);
+  // Suppress a line mismatch error
+  gcode_LastN += 1;
+  FlushSerialRequestResend();
 }
 
 #ifdef SCARA