diff --git a/app/models/sensor.rb b/app/models/sensor.rb
index c34f9682f..ff31d48b1 100644
--- a/app/models/sensor.rb
+++ b/app/models/sensor.rb
@@ -1,3 +1,8 @@
 class Sensor < ApplicationRecord
   belongs_to :device
+  validates  :device, presence: true
+  validates  :pin,    presence: true
+  validates  :pin,    uniqueness: { scope: :device }
+  validates  :pin,    numericality: { only_integer: true, greater_than_or_equal_to: 0 }
+  validates  :label,  presence: true
 end
diff --git a/app/mutations/sensors/create.rb b/app/mutations/sensors/create.rb
index a7170de84..ac7b8572e 100644
--- a/app/mutations/sensors/create.rb
+++ b/app/mutations/sensors/create.rb
@@ -1,10 +1,20 @@
 module Sensors
   class Create < Mutations::Command
+    MODES    = CeleryScriptSettingsBag::ALLOWED_PIN_MODES
+    BAD_MODE = CeleryScriptSettingsBag::BAD_ALLOWED_PIN_MODES
+
     required do
       model   :device, class: Device
       integer :pin
       string  :label
-      integer :mode, in: CeleryScriptSettingsBag::ALLOWED_PIN_MODES
+      integer :mode
+    end
+
+    def validate
+      if !MODES.include?(mode)
+        msg = BAD_MODE % [mode.to_s, MODES]
+        add_error :mode, :not_allowed, msg
+      end
     end
 
     def execute
diff --git a/app/mutations/sensors/destroy.rb b/app/mutations/sensors/destroy.rb
index 4beb289a7..f589b4a82 100644
--- a/app/mutations/sensors/destroy.rb
+++ b/app/mutations/sensors/destroy.rb
@@ -3,6 +3,7 @@ module Sensors
     required { model :sensor, class: Peripheral }
     IN_USE = "Can't delete sensor because the following sequences are still " \
              "using it: %s"
+    EDGE_NODE_NAME = "sensor_id"
 
     def execute
       sensor.destroy!
@@ -10,17 +11,16 @@ module Sensors
 
   private
 
-    def sequences_using_it
-      raise "UNCLEAR: Are we adding a `sensor_id` arg?"
-
-      @sequences_using_it ||= EdgeNode
-        .where(kind: "sensor_id", value: sensor.id)
-        .pluck(:sequence_id)
-    end
+    # def sequences_using_it
+    #   @sequences_using_it ||= EdgeNode
+    #     .where(kind: EDGE_NODE_NAME, value: sensor.id)
+    #     .pluck(:sequence_id)
+    # end
 
     def not_in_use?
-      names = Sequence.where(id: sequences_using_it).pluck(:name).join(", ")
-      add_error :sensor, :in_use, (IN_USE % [names]) if names.present?
+      puts "TOD: Add usage checks here. -RC"
+      # names = Sequence.where(id: sequences_using_it).pluck(:name).join(", ")
+      # add_error :sensor, :in_use, (IN_USE % [names]) if names.present?
     end
   end
 end
diff --git a/spec/mutations/sensors/create_spec.rb b/spec/mutations/sensors/create_spec.rb
new file mode 100644
index 000000000..044165a36
--- /dev/null
+++ b/spec/mutations/sensors/create_spec.rb
@@ -0,0 +1,19 @@
+require "spec_helper"
+
+describe Sensors::Create do
+  let(:device) { FactoryBot.create(:device) }
+
+  it "instantiates a sensor object" do
+    props = {device: device, pin: 1, label: "One", mode: 0}
+    obj = Sensors::Create.run!(props)
+    props.to_a.map { |(key, val)| expect(obj.send(key)).to eq(val)}
+  end
+
+  it "disallows bad PIN_MODEs" do
+    props = {device: device, pin: 1, label: "One", mode: -1}
+    result = Sensors::Create.run(props)
+    err = result.errors["mode"]
+    expect(err).to be
+    expect(err.message).to include("not a valid pin")
+  end
+end