diff --git a/lambda/airgate.c b/lambda/airgate.c
index ae8ad59..dae35d7 100644
--- a/lambda/airgate.c
+++ b/lambda/airgate.c
@@ -90,7 +90,7 @@
 }
 
 void setAirgate(uint8_t const target) {
-	if (target == getAirgate() || isAirgateBusy()) {
+	if (target == getAirgate() || isAirgateBusy() || isDriverFault()) {
 		return;
 	}
 	if (bit_is_clear(PORT, PIN_SLEEP)) {
@@ -117,6 +117,10 @@
 	return steps_c > 0;
 }
 
+bool isDriverFault(void) {
+	return bit_is_clear(PORT, PIN_FAULT);
+}
+
 void setSleepMode(bool const on) {
 	if (on) {
 		PORT &= ~(1 << PIN_SLEEP);
diff --git a/lambda/airgate.h b/lambda/airgate.h
index 5067773..dabb1ea 100644
--- a/lambda/airgate.h
+++ b/lambda/airgate.h
@@ -53,6 +53,11 @@
 bool isAirgateBusy(void);
 
 /**
+ * Returns true if the driver signals fault condition, false otherwise.
+ */
+bool isDriverFault(void);
+
+/**
  * Wakes up the driver or puts it in sleep mode.
  */
 void setSleepMode(bool const on);
diff --git a/lambda/messages.h b/lambda/messages.h
index 33011af..00e34e2 100644
--- a/lambda/messages.h
+++ b/lambda/messages.h
@@ -40,6 +40,8 @@
 	#define MSG_HEATER_OFF_0 "Oxygen sensor"
 	#define MSG_HEATER_OFF_1 "off"
 	#define MSG_HEATER_CURRENT "Heater current"
+	#define MSG_DRIVER_FAULT_0 "Airgate motor"
+	#define MSG_DRIVER_FAULT_1 "driver fault!"
 	#define MSG_TIME_SINCE_START "Time since start"
 
 #elif LANG == 1
@@ -70,6 +72,8 @@
 	#define MSG_HEATER_OFF_0 "Lambdasonde"
 	#define MSG_HEATER_OFF_1 "aus"
 	#define MSG_HEATER_CURRENT "Heizstrom"
+	#define MSG_DRIVER_FAULT_0 "Luftschieber-"
+	#define MSG_DRIVER_FAULT_1 "antrieb Fehler!"
 	#define MSG_TIME_SINCE_START "Zeit seit Start"
 
 #endif
diff --git a/lambda/rules.c b/lambda/rules.c
index a019959..cb695ad 100644
--- a/lambda/rules.c
+++ b/lambda/rules.c
@@ -225,18 +225,29 @@
 }
 
 /**
- * Heater rules applied to each not averaged measured heater current value.
+ * Notifies that the stepper motor driver signals fault condition.
  */
-Rule heaterRules[] = {
+static void driverFault(bool* const fired, Measurement const meas) {
+	if (isDriverFault()) {
+		alert_P(BEEPS, LENGTH, TONE, PSTR(MSG_DRIVER_FAULT_0),
+				PSTR(MSG_DRIVER_FAULT_1), true);
+	}
+}
+
+/**
+ * Rules applied to each measurement.
+ */
+Rule fastRules[] = {
 		{false, heaterReady},
 		{false, heaterFault},
-		{false, heaterTimeout}
+		{false, heaterTimeout},
+		{false, driverFault}
 };
 
 /**
  * Rules applied to every nth averaged measurement.
  */
-Rule rules[] = {
+Rule slowRules[] = {
 		{false, airgate50},
 		{false, airgate25},
 		{false, airgateClose},
@@ -256,8 +267,8 @@
 	tempIMax = MAX(tempIMax, meas.tempI);
 
 	// rules applied at each measurement
-	for (size_t i = 0; i < ARRAY_LENGTH(heaterRules); i++) {
-		heaterRules[i].cond(&(heaterRules[i].fired), meas);
+	for (size_t i = 0; i < ARRAY_LENGTH(fastRules); i++) {
+		fastRules[i].cond(&(fastRules[i].fired), meas);
 	}
 
 	// evaluation of the fire state and rules applied
@@ -265,8 +276,8 @@
 	if (measCount == MEAS_INT) {
 		measCount = 0;
 
-		for (size_t i = 0; i < ARRAY_LENGTH(rules); i++) {
-			rules[i].cond(&(rules[i].fired), meas);
+		for (size_t i = 0; i < ARRAY_LENGTH(slowRules); i++) {
+			slowRules[i].cond(&(slowRules[i].fired), meas);
 		}
 
 		// difference between current and previous temperature
@@ -299,13 +310,13 @@
 		state = undefined;
 	}
 
-	for (size_t i = 0; i < ARRAY_LENGTH(rules); i++) {
-		rules[i].fired = false;
+	for (size_t i = 0; i < ARRAY_LENGTH(slowRules); i++) {
+		slowRules[i].fired = false;
 	}
 	// default for warmStart should be true
-	rules[6].fired = true;
+	slowRules[6].fired = true;
 
-	for (size_t i = 0; i < ARRAY_LENGTH(heaterRules); i++) {
-		heaterRules[i].fired = false;
+	for (size_t i = 0; i < ARRAY_LENGTH(fastRules); i++) {
+		fastRules[i].fired = false;
 	}
 }