diff --git a/lambda-test/alert-test.c b/lambda-test/alert-test.c
index e6a621e..5a91f8c 100644
--- a/lambda-test/alert-test.c
+++ b/lambda-test/alert-test.c
@@ -14,10 +14,11 @@
 
 /* Module alert */
 
-static bool testOscillateBeep(void) {
-	extern uint8_t beepCount;
-	extern uint8_t oscCount;
+extern uint8_t beepCount;
+extern uint16_t beepLength;
+extern uint8_t oscCount;
 
+static bool testOscillateBeep(void) {
 	beepCount = 0;
 	oscCount = 0;
 
@@ -64,10 +65,6 @@
 }
 
 static bool testBeep(void) {
-	extern uint8_t beepCount;
-	extern uint16_t beepLength;
-	extern uint8_t oscCount;
-
 	beepCount = 0;
 	beepLength = 0;
 	oscCount = 0;
@@ -83,10 +80,6 @@
 }
 
 static bool testAlert(void) {
-	extern uint8_t beepCount;
-	extern uint16_t beepLength;
-	extern uint8_t oscCount;
-
 	beepCount = 0;
 	beepLength = 0;
 	oscCount = 0;
@@ -103,10 +96,6 @@
 }
 
 static bool testCancelAlert(void) {
-	extern uint8_t beepCount;
-	extern uint16_t beepLength;
-	extern uint8_t oscCount;
-
 	beepCount = 0;
 	beepLength = 0;
 	oscCount = 0;
diff --git a/lambda-test/command-test.c b/lambda-test/command-test.c
index afa4b7a..8474463 100644
--- a/lambda-test/command-test.c
+++ b/lambda-test/command-test.c
@@ -17,6 +17,8 @@
 
 /* Module command */
 
+extern uint8_t position;
+
 static bool testIsSimulation(void) {
 	setupPorts();
 	setHeatingOn(false);
@@ -58,8 +60,6 @@
 }
 
 static bool testCycleDisplay(void) {
-	extern uint8_t position;
-
 	cancelAlert(true);
 	assertTrue(position == 0);
 
diff --git a/lambda-test/display-test.c b/lambda-test/display-test.c
index 3535d74..24fe5d2 100644
--- a/lambda-test/display-test.c
+++ b/lambda-test/display-test.c
@@ -16,13 +16,16 @@
 
 /* Module display */
 
+extern uint8_t position;
+extern bool updatePending;
+
+extern uint8_t beepCount;
+extern uint16_t beepLength;
+
+extern Measurement measLatest;
+extern Measurement measMax; // = {0, 0, 2000};
+
 static bool testCycle(void) {
-	extern uint8_t position;
-	extern bool updatePending;
-
-	extern uint8_t beepCount;
-	extern uint16_t beepLength;
-
 	cancelAlert(true);
 	position = 0;
 	updatePending = false;
@@ -49,9 +52,6 @@
 }
 
 static bool testCycleCancelAlert(void) {
-	extern uint8_t position;
-	extern bool updatePending;
-
 	position = 0;
 	updatePending = false;
 
@@ -67,10 +67,6 @@
 }
 
 static bool testUpdateMeas(void) {
-	extern bool updatePending;
-	extern Measurement measLatest;
-	extern Measurement measMax; // = {0, 0, 2000};
-
 	updatePending = false;
 
 	// initial measurements
@@ -107,10 +103,6 @@
 }
 
 static bool testResetMeas(void) {
-	extern bool updatePending;
-	extern Measurement measLatest;
-	extern Measurement measMax;
-
 	updatePending = false;
 
 	resetDisplay();
@@ -124,8 +116,6 @@
 }
 
 static bool testUpdateDisplayIfPending(void) {
-	extern bool updatePending;
-
 	updatePending = true;
 
 	updateDisplayIfPending();
@@ -135,8 +125,6 @@
 }
 
 static bool testUpdateDisplayIfPendingAlertActive(void) {
-	extern bool updatePending;
-
 	updatePending = true;
 	alert(1, 1, 31, "", "", false);
 	assertTrue(isAlertActive());
diff --git a/lambda-test/rules-test.c b/lambda-test/rules-test.c
index 4205398..b9880ea 100644
--- a/lambda-test/rules-test.c
+++ b/lambda-test/rules-test.c
@@ -13,12 +13,13 @@
 #include "alert.h"
 #include "interrupts.h"
 
+/* Module rules */
+
 extern uint16_t age;
 extern int8_t dir;
+extern uint8_t airgate;
 extern Rule rules[];
 
-/* Module rules */
-
 static bool testAirgate50(void) {
 
 	Measurement meas = {0, 0, 0};
@@ -54,6 +55,7 @@
 	dir = 1;
 	reason(meas);
 	assertTrue(rules[0].fired);
+	assertTrue(50 == airgate);
 
 	cancelAlert(false);
 
@@ -95,6 +97,7 @@
 	dir = -1;
 	reason(meas);
 	assertTrue(rules[1].fired);
+	assertTrue(25 == airgate);
 
 	cancelAlert(false);
 
@@ -136,6 +139,7 @@
 	dir = -1;
 	reason(meas);
 	assertTrue(rules[2].fired);
+	assertTrue(0 == airgate);
 
 	cancelAlert(false);
 
@@ -149,21 +153,14 @@
 
 	setHeatingState(HEATING_READY);
 
-	meas.tempI = 99;
-	meas.lambda = 2000;
-	resetRules();
-	reason(meas);
-	assertFalse(rules[3].fired);
-
 	meas.tempI = 100;
 	meas.lambda = 2000;
-
 	resetRules();
 	reason(meas);
 	assertFalse(rules[3].fired);
 
-	meas.tempI = 99;
-	meas.lambda = 1199;
+	meas.tempI = 101;
+	meas.lambda = 2000;
 	resetRules();
 	reason(meas);
 	assertFalse(rules[3].fired);
@@ -172,7 +169,23 @@
 	meas.lambda = 1199;
 	resetRules();
 	reason(meas);
+	assertFalse(rules[3].fired);
+
+	meas.tempI = 101;
+	meas.lambda = 1199;
+	resetRules();
+	airgate = 100;
+	reason(meas);
+	assertFalse(rules[3].fired);
+	assertTrue(100 == airgate);
+
+	meas.tempI = 101;
+	meas.lambda = 1199;
+	resetRules();
+	airgate = 50;
+	reason(meas);
 	assertTrue(rules[3].fired);
+	assertTrue(100 == airgate);
 
 	meas.lambda = 1300;
 	age = 0;
@@ -184,6 +197,51 @@
 	return true;
 }
 
+static bool testTooLean(void) {
+
+	Measurement meas = {0, 0, 0};
+	dir = 0;
+
+	setHeatingState(HEATING_READY);
+
+	meas.tempI = 500;
+	meas.lambda = 1601;
+	resetRules();
+	reason(meas);
+	assertFalse(rules[4].fired);
+
+	meas.tempI = 501;
+	meas.lambda = 1300;
+	resetRules();
+	reason(meas);
+	assertFalse(rules[4].fired);
+
+	meas.tempI = 501;
+	meas.lambda = 1601;
+	resetRules();
+	airgate = 50;
+	reason(meas);
+	assertFalse(rules[4].fired);
+	assertTrue(50 == airgate);
+
+	meas.tempI = 501;
+	meas.lambda = 1601;
+	resetRules();
+	airgate = 100;
+	reason(meas);
+	assertTrue(rules[4].fired);
+	assertTrue(50 == airgate);
+
+	meas.lambda = 1500;
+	age = 0;
+	reason(meas);
+	assertFalse(rules[4].fired);
+
+	cancelAlert(false);
+
+	return true;
+}
+
 static bool testFireOut(void) {
 
 	resetRules();
@@ -193,27 +251,27 @@
 	meas.tempI = 50;
 	age = 0;
 	reason(meas);
-	assertFalse(rules[4].fired);
+	assertFalse(rules[5].fired);
 
 	meas.tempI = 100;
 	age = 0;
 	reason(meas);
-	assertFalse(rules[4].fired);
+	assertFalse(rules[5].fired);
 
 	meas.tempI = 125;
 	age = 0;
 	reason(meas);
-	assertFalse(rules[4].fired);
+	assertFalse(rules[5].fired);
 
 	meas.tempI = 99;
 	age = 0;
 	reason(meas);
-	assertTrue(rules[4].fired);
+	assertTrue(rules[5].fired);
 
 	meas.tempI = 125;
 	age = 0;
 	reason(meas);
-	assertFalse(rules[4].fired);
+	assertFalse(rules[5].fired);
 
 	cancelAlert(false);
 
@@ -438,6 +496,7 @@
 static const char testAirgate25_P[] PROGMEM = "testAirgate25";
 static const char testAirgateClose_P[] PROGMEM = "testAirgateClose";
 static const char testTooRich_P[] PROGMEM = "testTooRich";
+static const char testTooLean_P[] PROGMEM = "testTooLean";
 static const char testFireOut_P[] PROGMEM = "testFireOut";
 static const char testHeatingReady_P[] PROGMEM = "testHeatingReady";
 static const char testHeatingFaultNoconn_P[] PROGMEM = "testHeatingFaultNoconn";
@@ -453,6 +512,7 @@
 		{class, testAirgate25_P, testAirgate25},
 		{class, testAirgateClose_P, testAirgateClose},
 		{class, testTooRich_P, testTooRich},
+		{class, testTooLean_P, testTooLean},
 		{class, testFireOut_P, testFireOut},
 		{class, testHeatingReady_P, testHeatingReady},
 		{class, testHeatingFaultNoconn_P, testHeatingFaultNoconn},
diff --git a/lambda/TODO b/lambda/TODO
index bfcc46b..ea873a1 100644
--- a/lambda/TODO
+++ b/lambda/TODO
@@ -6,11 +6,9 @@
 - Take in account F_CPU everywhere CPU speed matters
 
 * Functionality
+- Show fire dir and (recommended) airgate position?
   
 * Circuit
-- Look at oxygen sensor voltage with voltmeter/oscilloscope - is the voltage
-  really so unstable?
-- Put button and beeper pins in pins.h (watch out with OCR1A)
 - AVCC should be connected to VCC via an LC network
 
 * Release/put in Makefile?
diff --git a/lambda/alert.c b/lambda/alert.c
index 916874c..2b58d93 100644
--- a/lambda/alert.c
+++ b/lambda/alert.c
@@ -13,6 +13,7 @@
 #include "alert.h"
 #include "sensors.h"
 #include "display.h"
+#include "pins.h"
 
 uint8_t beepCount = 0;
 uint16_t beepLength = 0;
@@ -28,11 +29,11 @@
 	}
 	if (oscCount == 0) {
 		// turn beep on
-		TCCR1A |= (1 << COM1A0);
+		TCCR1A |= (1 << PIN_BEEPER_TOGGLE);
 	}
 	if (oscCount == beepLength) {
 		// turn beep off
-		TCCR1A &= ~(1 << COM1A0);
+		TCCR1A &= ~(1 << PIN_BEEPER_TOGGLE);
 		beepCount--;
 		if (beepCount == 0 && ! keepActive) {
 			alertActive = false;
@@ -76,7 +77,7 @@
 	beepCount = 0;
 	oscCount = 0;
 	// turn beep off
-	TCCR1A &= ~(1 << COM1A0);
+	TCCR1A &= ~(1 << PIN_BEEPER_TOGGLE);
 	if (! keepActive || all) {
 		alertActive = false;
 	}
diff --git a/lambda/display.c b/lambda/display.c
index 3a03c21..b31bf76 100644
--- a/lambda/display.c
+++ b/lambda/display.c
@@ -21,6 +21,7 @@
 #include "display.h"
 #include "alert.h"
 #include "messages.h"
+#include "rules.h"
 
 #define MENU_OFF 0
 #define MENU_MAX_VALUES 1
@@ -66,7 +67,7 @@
 		snprintf(line1, sizeof(line1), "L  %d.%02d %s %s",
 				lambdaT.quot, abs(lambdaT.rem), toInfo(lambdax100), hint);
 	} else {
-		snprintf(line1, sizeof(line1), "L   -%12s", hint);
+		snprintf(line1, sizeof(line1), "L   -%11s", hint);
 	}
 	setText(line0, line1);
 }
@@ -79,7 +80,7 @@
 	div_t ampsT = div(ampsx100, 100);
 
 	char line1[17];
-	snprintf(line1, sizeof(line1), "%d.%02dA", ampsT.quot, abs(ampsT.rem));
+	snprintf(line1, sizeof(line1), "%d.%02d Amp", ampsT.quot, abs(ampsT.rem));
 	setText(MSG_HEATING_CURRENT, line1);
 }
 
@@ -130,7 +131,7 @@
 		updatePending = false;
 
 		if (position == MENU_MAX_VALUES) {
-			displayMeas(measMax, "|>");
+			displayMeas(measMax, " ^");
 		} else if (position == MENU_LAST_TEXT) {
 			setText(lastLine0, lastLine1);
 		} else if (position == MENU_CURRENT) {
@@ -138,7 +139,13 @@
 		} else if (position == MENU_TIME) {
 			displayTime();
 		} else {
-			displayMeas(measLatest, "  ");
+			char* hint;
+			switch (getDir()) {
+				case DIR_BURN_UP: hint = " >"; break;
+				case DIR_BURN_DOWN: hint = " <"; break;
+				default: hint = " -"; break;
+			}
+			displayMeas(measLatest, hint);
 		}
 	}
 }
diff --git a/lambda/interrupts.c b/lambda/interrupts.c
index 7993902..6779e27 100644
--- a/lambda/interrupts.c
+++ b/lambda/interrupts.c
@@ -18,6 +18,7 @@
 #include "sensors.h"
 #include "display.h"
 #include "alert.h"
+#include "pins.h"
 
 static volatile bool buttonPressed = false;
 static volatile uint32_t ints = 0;
@@ -72,14 +73,14 @@
 }
 
 void setupPorts(void) {
-	// pull-up resistor for the mouton
-	PORTB |= (1 << PB0);
+	// pull-up resistor for the menu button
+	PORT |= (1 << PIN_BUTTON);
 
 	// enable beep output pin
-	DDRB |= (1 << PB1);
+	DDR |= (1 << PIN_BEEPER);
 
-	// enable oxygen sensor heating control output pin
-	DDRB |= (1 << PB2);
+	// enable oxygen sensor heater control output pin
+	DDR |= (1 << PIN_HEATER);
 }
 
 void setupSleepMode(void) {
@@ -112,7 +113,7 @@
 	TCCR1B |= (1 << WGM12);
 	// timer1 clock prescaler/8
 	TCCR1B |= (1 << CS11);
-	// toggles PB1 at 7.8 kHz generating a 3.9 kHz beep
+	// timer1 Compare Match at 7.8 kHz generating a 3.9 kHz beep
 	// OCR1A = 15;
 	// 2 kHz is less noisy on the small piezo beeper
 	OCR1A = 31;
diff --git a/lambda/lambda.c b/lambda/lambda.c
index ddcbefe..70b6768 100644
--- a/lambda/lambda.c
+++ b/lambda/lambda.c
@@ -51,7 +51,6 @@
 	// spend some time on being polite
 	while (getTime() < 3) {}
 	setHeatingOn(true);
-	while (getTime() < 4) {}
 
 	uint32_t ints = 0;
 	Measurement meas;
diff --git a/lambda/pins.h b/lambda/pins.h
index 71748b6..931b6cd 100644
--- a/lambda/pins.h
+++ b/lambda/pins.h
@@ -7,6 +7,8 @@
  *      Author: dode@luniks.net
  */
 
+#include <avr/io.h>
+
 #ifndef PINS_H_
 #define PINS_H_
 
@@ -19,6 +21,19 @@
 /** ADC pin for the LSM 11 oxygen sensor heating current */
 #define ADC_HEATING PC3
 
+/** Port for menu button, beeper and oxygen sensor heater */
+#define PORT PORTB
+/** DDR for menu button, beeper and oxygen sensor heater */
+#define DDR DDRB
+/** Pin for the menu button */
+#define PIN_BUTTON PB0
+/** Pin for the beeper */
+#define PIN_BEEPER PB1
+/** Toggle beeper pin OC1A/PB1 */
+#define PIN_BEEPER_TOGGLE COM1A0
+/** Pin for the oxygen sensor heater */
+#define PIN_HEATER PB2
+
 /* Pins for the LCD */
 #define LCD_PORT PORTD
 #define LCD_DDR	 DDRD
diff --git a/lambda/rules.c b/lambda/rules.c
index 9bad3f5..9d801be 100644
--- a/lambda/rules.c
+++ b/lambda/rules.c
@@ -16,16 +16,17 @@
 #define LENGTH 20
 #define TONE 31
 
-#define DIR_NONE 0
-#define DIR_BURN_UP 1
-#define DIR_BURN_DOWN -1
-
 uint8_t age = 0;
 int8_t dir = 0;
+uint8_t airgate = 100;
 
 static Measurement rulesMeasMax = {0, 0, 2000, 0};
 static Measurement rulesMeasPrev = {0, 0, 2000, 0};
 
+int8_t getDir(void) {
+	return dir;
+}
+
 /**
  * Reminds to set the air gate to 50% when the fire is still building up
  * and the temperature has reached 500°C.
@@ -33,6 +34,7 @@
 static void airgate50(bool* const fired, int8_t const dir,
 		Measurement const meas) {
 	if (! *fired && dir == DIR_BURN_UP && meas.tempI >= 500) {
+		airgate = 50;
 		alert_P(BEEPS, LENGTH, TONE, PSTR(MSG_AIRGATE_50_0), PSTR(""), false);
 		*fired = true;
 	}
@@ -45,6 +47,7 @@
 static void airgate25(bool* const fired, int8_t const dir,
 		Measurement const meas) {
 	if (! *fired && dir == DIR_BURN_DOWN && meas.tempI < 800) {
+		airgate = 25;
 		alert_P(BEEPS, LENGTH, TONE, PSTR(MSG_AIRGATE_25_0), PSTR(""), false);
 		*fired = true;
 	}
@@ -56,8 +59,9 @@
  */
 static void airgateClose(bool* const fired, int8_t const dir,
 		Measurement const meas) {
-	if (! *fired && dir == DIR_BURN_DOWN && meas.tempI < 400) {
+	if (! *fired && dir == DIR_BURN_DOWN && meas.tempI < 450) {
 		setHeatingOn(false);
+		airgate = 0;
 		alert_P(BEEPS, LENGTH, TONE,
 				PSTR(MSG_AIRGATE_CLOSE_0), PSTR(""), false);
 		*fired = true;
@@ -65,13 +69,13 @@
 }
 
 /**
- * Notifies that the combustion is too rich and to open the air gate
- * if possible.
+ * Notifies that the combustion is too rich and to open the air gate.
  */
 static void tooRich(bool* const fired, int8_t const dir,
 		Measurement const meas) {
-	if (! *fired && meas.tempI >= 100 && meas.lambda < 1200 &&
-			getHeatingState() == HEATING_READY) {
+	if (! *fired && meas.tempI > 100 && meas.lambda < 1200 &&
+			getHeatingState() == HEATING_READY && airgate < 100) {
+		airgate = 100;
 		alert_P(BEEPS, LENGTH, TONE,
 				PSTR(MSG_TOO_RICH_0), PSTR(MSG_TOO_RICH_1), false);
 		*fired = true;
@@ -82,6 +86,22 @@
 }
 
 /**
+ * Notifies that the combustion is lean (again) and to set the air gate to 50%.
+ */
+static void tooLean(bool* const fired, int8_t const dir,
+		Measurement const meas) {
+	if (! *fired && meas.tempI > 500 && meas.lambda > 1600 &&
+			getHeatingState() == HEATING_READY && airgate > 50) {
+		airgate = 50;
+		alert_P(BEEPS, LENGTH, TONE, PSTR(MSG_AIRGATE_50_0), PSTR(""), false);
+		*fired = true;
+	}
+	if (meas.lambda <= 1500) {
+		*fired = false;
+	}
+}
+
+/**
  * Notifies that the fire might have gone out at the beginning of building up.
  */
 static void fireOut(bool* const fired, int8_t const dir,
@@ -144,7 +164,6 @@
 }
 
 // TODO what if fired up again without reset?
-// TODO what if reset during burndown?
 
 /**
  * Rules applied to every nth averaged measurement
@@ -154,6 +173,7 @@
 		{false, airgate25},
 		{false, airgateClose},
 		{false, tooRich},
+		{false, tooLean},
 		{false, fireOut}
 };
 
@@ -215,6 +235,7 @@
 
 	age = 0;
 	dir = DIR_NONE;
+	airgate = 100;
 
 	size_t rulesSize = sizeof(rules) / sizeof(rules[0]);
 	for (size_t i = 0; i < rulesSize; i++) {
diff --git a/lambda/rules.h b/lambda/rules.h
index 660deb5..a3db885 100644
--- a/lambda/rules.h
+++ b/lambda/rules.h
@@ -11,6 +11,10 @@
 #include <stdbool.h>
 #include "sensors.h"
 
+#define DIR_NONE 0
+#define DIR_BURN_UP 1
+#define DIR_BURN_DOWN -1
+
 /**
  * An attempt to create some sort of rule "object".
  */
@@ -20,6 +24,12 @@
 } Rule;
 
 /**
+ * Returns the "direction" of the fire, i.e. DIR_BURN_DOWN when it is burning
+ * down.
+ */
+int8_t getDir(void);
+
+/**
  * Applies all rules against the given measurements.
  */
 void reason(Measurement meas);
diff --git a/lambda/sensors.h b/lambda/sensors.h
index 145d352..ba77c5e 100644
--- a/lambda/sensors.h
+++ b/lambda/sensors.h
@@ -13,7 +13,6 @@
 
 #include <stdio.h>
 
-/* 0.1 Ohm 10% measured 0.111 Ohm */
 #define SHUNT_MILLIOHMS 100
 #define HEATING_READY_MA 1400
 #define HEATING_SHORT_MA 7500