diff --git a/firmware/controllers/system_fsio.h b/firmware/controllers/system_fsio.h
index d316277fc0..006a7cc9aa 100644
--- a/firmware/controllers/system_fsio.h
+++ b/firmware/controllers/system_fsio.h
@@ -1,4 +1,4 @@
-// this https://en.wikipedia.org/wiki/Reverse_Polish_notation is generated automatically
+// this https://en.wikipedia.org/wiki/Reverse_Polish_notation SHOULD BE generated automatically
 // from controllers/system_fsio.txt
 // on 2019-09-08_16_41_20_788
 //
@@ -25,9 +25,9 @@
 // Human-readable: coolant > 120
 #define TOO_HOT_LOGIC "coolant 120 >"
 
-// Human-readable: ac_on_switch & rpm > 850 & time_since_ac_on_switch > 0.3
-// ac_on_switch rpm & 850 time_since_ac_on_switch & > 0.3 >
-#define AC_RELAY_LOGIC "ac_on_switch rpm & 850 >"
+// Human-readable: ac_on_switch & (rpm > 850) & (time_since_ac_on_switch > 0.3)
+// ac_on_switch rpm 850 > & time_since_ac_on_switch 0.3 > &
+#define AC_RELAY_LOGIC "ac_on_switch rpm 850 > &"
 // Combined RPM, CLT and VBATT warning light
 
 // Human-readable: (rpm > fsio_setting(2)) | ((coolant > fsio_setting(3)) | (vbatt < fsio_setting(4)))
diff --git a/firmware/controllers/system_fsio.txt b/firmware/controllers/system_fsio.txt
index 8a6148ca9f..1ad5a4e5c1 100644
--- a/firmware/controllers/system_fsio.txt
+++ b/firmware/controllers/system_fsio.txt
@@ -17,7 +17,7 @@ ALTERNATOR_LOGIC=vbatt < 14.5
 
 TOO_HOT_LOGIC=coolant > 120
 
-AC_RELAY_LOGIC=ac_on_switch & rpm > 850
+AC_RELAY_LOGIC=ac_on_switch & (rpm > 850)
 
 # Combined RPM, CLT and VBATT warning light
 COMBINED_WARNING_LIGHT=(rpm > fsio_setting(2)) | ((coolant > fsio_setting(3)) | (vbatt < fsio_setting(4)))
diff --git a/java_console/ui/src/main/java/com/rusefi/ui/widgets/AnyCommand.java b/java_console/ui/src/main/java/com/rusefi/ui/widgets/AnyCommand.java
index 7b7b8e4a13..124d05da4d 100644
--- a/java_console/ui/src/main/java/com/rusefi/ui/widgets/AnyCommand.java
+++ b/java_console/ui/src/main/java/com/rusefi/ui/widgets/AnyCommand.java
@@ -133,7 +133,14 @@ public class AnyCommand {
     public static String prepareCommand(String rawCommand, LinkManager linkManager) {
         try {
             if (rawCommand.startsWith("eval" + " ")) {
-                return prepareEvalCommand(rawCommand);
+                String result = prepareEvalCommand(rawCommand);
+                if (result.equals(rawCommand)) {
+                    // result was not translated
+                    MessagesCentral.getInstance().postMessage(AnyCommand.class, "Not valid expression");
+                    MessagesCentral.getInstance().postMessage(AnyCommand.class, "Please try eval \"2 + 2\"");
+                    MessagesCentral.getInstance().postMessage(AnyCommand.class, "For RPN use rpn_eval \"2 2 +\"");
+                }
+                return result;
             } else if (rawCommand.toLowerCase().startsWith("stim_check" + " ")) {
                 handleStimulationSelfCheck(rawCommand, linkManager);
                 return null;
@@ -202,12 +209,16 @@ public class AnyCommand {
         MessagesCentral.getInstance().postMessage(AnyCommand.class, "Human form is \"" + humanForm + "\"");
     }
 
-    private static String prepareEvalCommand(String rawCommand) {
+    public static String prepareEvalCommand(String rawCommand) {
         String[] parts = rawCommand.split(" ", 2);
         if (parts.length != 2)
             return rawCommand; // let's ignore invalid command
 
-        return "rpn_eval" + " " + quote(infix2postfix(unquote(parts[1])));
+        try {
+            return "rpn_eval" + " " + quote(infix2postfix(unquote(parts[1])));
+        } catch (IllegalArgumentException e) {
+            return rawCommand;
+        }
     }
 
     private static String quote(String s) {
diff --git a/java_console/ui/src/main/java/com/rusefi/ui/widgets/test/AnyCommandTest.java b/java_console/ui/src/main/java/com/rusefi/ui/widgets/test/AnyCommandTest.java
index 54c6bed599..9a154ccfd4 100644
--- a/java_console/ui/src/main/java/com/rusefi/ui/widgets/test/AnyCommandTest.java
+++ b/java_console/ui/src/main/java/com/rusefi/ui/widgets/test/AnyCommandTest.java
@@ -14,6 +14,11 @@ public class AnyCommandTest {
         return AnyCommand.prepareCommand(rawCommand, null);
     }
 
+    @Test
+    public void testNoExceptionIsThrown() {
+        assertEquals("eval \"2 2 +\"", AnyCommand.prepareEvalCommand("eval \"2 2 +\""));
+    }
+
     @Test
     public void testUnquote() {
         assertEquals("1 2 3", AnyCommand.unquote("  \"1 2 3\"  "));