diff --git a/src/adc121c021/adc121c021.cxx b/src/adc121c021/adc121c021.cxx
index 5c5438a4..41808b9a 100644
--- a/src/adc121c021/adc121c021.cxx
+++ b/src/adc121c021/adc121c021.cxx
@@ -79,12 +79,20 @@ mraa_result_t ADC121C021::writeWord(uint8_t reg, uint16_t word)
 
 uint8_t ADC121C021::readByte(uint8_t reg)
 {
-  return mraa_i2c_read_byte_data(m_i2c, reg);
+  int val = mraa_i2c_read_byte_data(m_i2c, reg);
+  if (val != -1) {
+    return (uint8_t) val;
+  }
+  return 0;
 }
 
 uint16_t ADC121C021::readWord(uint8_t reg)
 {
-  uint16_t val = mraa_i2c_read_word_data(m_i2c, reg);
+  int x = mraa_i2c_read_word_data(m_i2c, reg);
+  if (x == -1) {
+    return 0;
+  }
+  uint16_t val = (uint16_t) x;
   uint8_t b1;
 
   // The value returned is in the wrong byte order, so we need to swap them
diff --git a/src/ecs1030/ecs1030.cxx b/src/ecs1030/ecs1030.cxx
index 4db49fab..90dd60a7 100644
--- a/src/ecs1030/ecs1030.cxx
+++ b/src/ecs1030/ecs1030.cxx
@@ -59,6 +59,8 @@ ECS1030::getCurrency_A () {
 
     for (int i = 0; i < NUMBER_OF_SAMPLES; i++) {
         sensorValue = mraa_aio_read (m_dataPinCtx);
+        if (sensorValue == -1) throw std::runtime_error(std::string(__FUNCTION__) +
+                                                        ": Failed to do an aio read.");
         volt = (VOLT_M * sensorValue) - 2.5;
         volt = volt * volt;
         rms = rms + volt;
@@ -77,6 +79,8 @@ ECS1030::getCurrency_B () {
     for (int i = 0; i < NUMBER_OF_SAMPLES; i++) {
         m_lastSample = m_sample;
         m_sample = mraa_aio_read (m_dataPinCtx);
+        if (m_sample == -1) throw std::runtime_error(std::string(__FUNCTION__) +
+                                                     ": Failed to do an aio read.");
         m_lastFilter = m_filteredSample;
         m_filteredSample = 0.996 * (m_lastFilter + m_sample - m_lastSample);
         sumCurrency += (m_filteredSample * m_filteredSample);
diff --git a/src/enc03r/enc03r.cxx b/src/enc03r/enc03r.cxx
index ee2da1ea..7dc4f65f 100644
--- a/src/enc03r/enc03r.cxx
+++ b/src/enc03r/enc03r.cxx
@@ -51,7 +51,10 @@ ENC03R::~ENC03R()
 
 unsigned int ENC03R::value()
 {
-  return mraa_aio_read(m_aio);
+  int x = mraa_aio_read(m_aio);
+  if (x == -1) throw std::out_of_range(std::string(__FUNCTION__) +
+                                       ": Failed to do an aio read.");
+  return (unsigned int) x;
 }
 
 void ENC03R::calibrate(unsigned int samples)
@@ -62,6 +65,8 @@ void ENC03R::calibrate(unsigned int samples)
   for (int i=0; i<samples; i++)
     {
       val = mraa_aio_read(m_aio);
+      if (val == -1) throw std::out_of_range(std::string(__FUNCTION__) +
+                                             ": Failed to do an aio read.");
       total += (float)val;
       usleep(2000);
     }
diff --git a/src/gp2y0a/gp2y0a.cxx b/src/gp2y0a/gp2y0a.cxx
index ecc8fd6c..0b375a90 100644
--- a/src/gp2y0a/gp2y0a.cxx
+++ b/src/gp2y0a/gp2y0a.cxx
@@ -57,6 +57,8 @@ float GP2Y0A::value(float aref, uint8_t samples)
   for (int i=0; i<samples; i++)
     {
       val = mraa_aio_read(m_aio);
+      if (val != -1) throw std::runtime_error(std::string(__FUNCTION__) +
+                                              ": Failed to do an aio read.");
       sum += val;
     }
 
diff --git a/src/grove/grove.cxx b/src/grove/grove.cxx
index 1cc39129..99733de8 100644
--- a/src/grove/grove.cxx
+++ b/src/grove/grove.cxx
@@ -127,7 +127,10 @@ GroveTemp::~GroveTemp()
 
 int GroveTemp::value ()
 {
-    int a = mraa_aio_read(m_aio) * m_scale;
+    float a = (float) mraa_aio_read(m_aio);
+    if (a == -1.0) return -1;
+    // Apply scale factore after error check
+    a *= m_scale;
     float r = (float)(1023.0-a)*10000.0/a;
     float t = 1.0/(log(r/10000.0)/3975.0 + 1.0/298.15)-273.15;
     return (int) round(t);
@@ -159,6 +162,7 @@ int GroveLight::value()
 {
     // rough conversion to lux, using formula from Grove Starter Kit booklet
     float a = (float) mraa_aio_read(m_aio);
+    if (a == -1.0) return -1;
     a = 10000.0/pow(((1023.0-a)*10.0/a)*15.0,4.0/3.0);
     return (int) round(a);
 }
diff --git a/src/groveemg/groveemg.cxx b/src/groveemg/groveemg.cxx
index 2685dfda..538c6b50 100644
--- a/src/groveemg/groveemg.cxx
+++ b/src/groveemg/groveemg.cxx
@@ -53,6 +53,8 @@ void GroveEMG::calibrate()
 	for (int i=0; i<1100; i++)
 	{
 		val = mraa_aio_read(m_aio);
+                if (val != -1) throw std::runtime_error(std::string(__FUNCTION__) +
+                                                        ": Failed to do an aio read.");
 		sum += val;
 		usleep(1000);
 	}
diff --git a/src/grovegsr/grovegsr.cxx b/src/grovegsr/grovegsr.cxx
index 487fb223..17b19c58 100644
--- a/src/grovegsr/grovegsr.cxx
+++ b/src/grovegsr/grovegsr.cxx
@@ -54,6 +54,8 @@ void GroveGSR::calibrate()
 	for(int i=0; i<500; i++)
 	{
 		val = mraa_aio_read(m_aio);
+		if (val != -1) throw std::runtime_error(std::string(__FUNCTION__) +
+			                                ": Failed to do an aio read.");
 		sum += val;
 		usleep(5000);
 	}
diff --git a/src/groveo2/groveo2.cxx b/src/groveo2/groveo2.cxx
index 3c2e6194..b982d3ff 100644
--- a/src/groveo2/groveo2.cxx
+++ b/src/groveo2/groveo2.cxx
@@ -49,6 +49,7 @@ GroveO2::~GroveO2()
 float GroveO2::voltageValue()
 {
 	int val = mraa_aio_read(m_aio);
+	if (val == -1) return -1.0f;
 	float sensorVoltage = (val/1024.0) * 5.0;
 	sensorVoltage = (sensorVoltage/201.0) * 10000.0;
 	return sensorVoltage;
diff --git a/src/grovevdiv/grovevdiv.cxx b/src/grovevdiv/grovevdiv.cxx
index 91485b7b..b1ebe154 100644
--- a/src/grovevdiv/grovevdiv.cxx
+++ b/src/grovevdiv/grovevdiv.cxx
@@ -53,6 +53,7 @@ unsigned int GroveVDiv::value(unsigned int samples)
   for (int i=0; i<samples; i++)
     {
       sum += mraa_aio_read(m_aio);
+      if (sum == -1) return 0;
       usleep(2000);
     }
         
diff --git a/src/guvas12d/guvas12d.cxx b/src/guvas12d/guvas12d.cxx
index 2fd87897..063e42db 100644
--- a/src/guvas12d/guvas12d.cxx
+++ b/src/guvas12d/guvas12d.cxx
@@ -54,6 +54,7 @@ float GUVAS12D::value(float aref, unsigned int samples)
   for (int i=0; i<samples; i++)
     {
       val = mraa_aio_read(m_aio);
+      if (val == -1) return -1;
       sum += val;
       usleep(2000);
     }
diff --git a/src/ina132/ina132.cxx b/src/ina132/ina132.cxx
index c66a145e..11ed525d 100644
--- a/src/ina132/ina132.cxx
+++ b/src/ina132/ina132.cxx
@@ -55,6 +55,7 @@ float INA132::value()
 	for(i=0;i<10;i++)
 	{
 		val = mraa_aio_read(m_aio);
+                if (val == -1) return -1;
 		v = val*5.00/1023;
 		sum += v;
 		usleep(10000);
diff --git a/src/joystick12/joystick12.cxx b/src/joystick12/joystick12.cxx
index c6789494..4f7245bf 100644
--- a/src/joystick12/joystick12.cxx
+++ b/src/joystick12/joystick12.cxx
@@ -75,6 +75,7 @@ Joystick12::~Joystick12() {
 
 float Joystick12::getXInput() {
     float in = mraa_aio_read (m_joystickCtxX);
+    if (in == -1.0) return -1;
     if (in < X_left) return -1;
     if (in < X_center) return -(X_center - in) / (X_center - X_left);
     if (in == X_center) return 0;
@@ -86,6 +87,7 @@ float Joystick12::getXInput() {
 
 float Joystick12::getYInput() {
     float  in = mraa_aio_read (m_joystickCtxY);
+    if (in == -1.0) return -1;
     if (in < Y_left) return -1;
     if (in < Y_center) return -(Y_center - in) / (Y_center - Y_left);
     if (in == Y_center) return 0;
diff --git a/src/maxsonarez/maxsonarez.cxx b/src/maxsonarez/maxsonarez.cxx
index 9c5330d8..d6974e71 100644
--- a/src/maxsonarez/maxsonarez.cxx
+++ b/src/maxsonarez/maxsonarez.cxx
@@ -55,6 +55,9 @@ MAXSONAREZ::~MAXSONAREZ()
 int MAXSONAREZ::inches()
 {
   int val = mraa_aio_read(m_aio);
+  if (val == -1) {
+    return -1;
+  }
   float volts = float(val) * (m_aref / m_aRes);
 
   return int(volts / m_vI);
diff --git a/src/mic/mic.cxx b/src/mic/mic.cxx
index 2a0f4066..8a4978cd 100644
--- a/src/mic/mic.cxx
+++ b/src/mic/mic.cxx
@@ -69,7 +69,11 @@ Microphone::getSampledWindow (unsigned int freqMS, int numberOfSamples,
     }
 
     while (sampleIdx < numberOfSamples) {
-        buffer[sampleIdx++] = mraa_aio_read (m_micCtx);
+        int x = mraa_aio_read (m_micCtx);
+        if (x == -1) {
+            return 0;
+        }
+        buffer[sampleIdx++] = x;
         usleep(freqMS * 1000);
     }
 
diff --git a/src/otp538u/otp538u.cxx b/src/otp538u/otp538u.cxx
index e7ef1b6e..8fd830cb 100644
--- a/src/otp538u/otp538u.cxx
+++ b/src/otp538u/otp538u.cxx
@@ -92,6 +92,10 @@ float OTP538U::ambientTemperature()
   for (int i=0; i<samples; i++)
     {
       val = mraa_aio_read(m_aioA);
+      if (val == -1) {
+          throw std::runtime_error(std::string(__FUNCTION__) +
+                                   ": failed to do aio read");
+      }
       temp += val;
       usleep(10000);
     }
@@ -153,6 +157,11 @@ float OTP538U::objectTemperature()
   for (int i=0; i<samples; i++)
     {
       val = mraa_aio_read(m_aioO);
+      if (val == -1) {
+          throw std::runtime_error(std::string(__FUNCTION__) +
+                                               ": failed to do aio read.");
+          return 0;
+      }
       temp += val;
       usleep(10000);
     }
diff --git a/src/ta12200/ta12200.cxx b/src/ta12200/ta12200.cxx
index 67244ad2..bc29c905 100644
--- a/src/ta12200/ta12200.cxx
+++ b/src/ta12200/ta12200.cxx
@@ -82,18 +82,22 @@ uint32_t TA12200::getMillis()
 }
 
 
-unsigned int TA12200::highestValue()
+int TA12200::highestValue()
 {
-  unsigned int hiVal = 0;
-  unsigned int val;
+  int hiVal = 0;
+  int val;
   uint32_t start = getMillis();
 
   // 1 second
   while (getMillis() < (start + 1000))
     {
       val = mraa_aio_read(m_aio);
-      if (val > hiVal)
+      if (val == -1) {
+        return -1;
+      }
+      if (val > hiVal) {
         hiVal = val;
+      }
     }
         
   return hiVal;
diff --git a/src/ta12200/ta12200.hpp b/src/ta12200/ta12200.hpp
index b3561d48..cc025e0c 100644
--- a/src/ta12200/ta12200.hpp
+++ b/src/ta12200/ta12200.hpp
@@ -89,9 +89,9 @@ namespace upm {
     /**
      * Gets the conversion value from the sensor
      *
-     * @return Highest value obtained over 1 second of measuring
+     * @return Highest value obtained over 1 second of measuring or -1 if error
      */
-    unsigned int highestValue();
+    int highestValue();
 
     /**
      * Computes the measured voltage