diff --git a/inputs/day5/part2/0 b/inputs/day5/part2/0
new file mode 100644
index 0000000..2626616
--- /dev/null
+++ b/inputs/day5/part2/0
@@ -0,0 +1 @@
+3,9,8,9,10,9,4,9,99,-1,8
diff --git a/inputs/day5/part2/1 b/inputs/day5/part2/1
new file mode 100644
index 0000000..2626616
--- /dev/null
+++ b/inputs/day5/part2/1
@@ -0,0 +1 @@
+3,9,8,9,10,9,4,9,99,-1,8
diff --git a/inputs/day5/part2/10 b/inputs/day5/part2/10
new file mode 100644
index 0000000..62b0c3f
--- /dev/null
+++ b/inputs/day5/part2/10
@@ -0,0 +1 @@
+3,21,1008,21,8,20,1005,20,22,107,8,21,20,1006,20,31,1106,0,36,98,0,0,1002,21,125,20,4,20,1105,1,46,104,999,1105,1,46,1101,1000,1,20,4,20,1105,1,46,98,99
diff --git a/inputs/day5/part2/11 b/inputs/day5/part2/11
new file mode 100644
index 0000000..62b0c3f
--- /dev/null
+++ b/inputs/day5/part2/11
@@ -0,0 +1 @@
+3,21,1008,21,8,20,1005,20,22,107,8,21,20,1006,20,31,1106,0,36,98,0,0,1002,21,125,20,4,20,1105,1,46,104,999,1105,1,46,1101,1000,1,20,4,20,1105,1,46,98,99
diff --git a/inputs/day5/part2/2 b/inputs/day5/part2/2
new file mode 100644
index 0000000..2626616
--- /dev/null
+++ b/inputs/day5/part2/2
@@ -0,0 +1 @@
+3,9,8,9,10,9,4,9,99,-1,8
diff --git a/inputs/day5/part2/3 b/inputs/day5/part2/3
new file mode 100644
index 0000000..124bbb7
--- /dev/null
+++ b/inputs/day5/part2/3
@@ -0,0 +1 @@
+3,9,7,9,10,9,4,9,99,-1,8
diff --git a/inputs/day5/part2/4 b/inputs/day5/part2/4
new file mode 100644
index 0000000..124bbb7
--- /dev/null
+++ b/inputs/day5/part2/4
@@ -0,0 +1 @@
+3,9,7,9,10,9,4,9,99,-1,8
diff --git a/inputs/day5/part2/5 b/inputs/day5/part2/5
new file mode 100644
index 0000000..1a710f8
--- /dev/null
+++ b/inputs/day5/part2/5
@@ -0,0 +1 @@
+3,3,1108,-1,8,3,4,3,99
diff --git a/inputs/day5/part2/6 b/inputs/day5/part2/6
new file mode 100644
index 0000000..1a710f8
--- /dev/null
+++ b/inputs/day5/part2/6
@@ -0,0 +1 @@
+3,3,1108,-1,8,3,4,3,99
diff --git a/inputs/day5/part2/7 b/inputs/day5/part2/7
new file mode 100644
index 0000000..1c96db8
--- /dev/null
+++ b/inputs/day5/part2/7
@@ -0,0 +1 @@
+3,3,1107,-1,8,3,4,3,99
diff --git a/inputs/day5/part2/8 b/inputs/day5/part2/8
new file mode 100644
index 0000000..1c96db8
--- /dev/null
+++ b/inputs/day5/part2/8
@@ -0,0 +1 @@
+3,3,1107,-1,8,3,4,3,99
diff --git a/inputs/day5/part2/9 b/inputs/day5/part2/9
new file mode 100644
index 0000000..62b0c3f
--- /dev/null
+++ b/inputs/day5/part2/9
@@ -0,0 +1 @@
+3,21,1008,21,8,20,1005,20,22,107,8,21,20,1006,20,31,1106,0,36,98,0,0,1002,21,125,20,4,20,1105,1,46,104,999,1105,1,46,1101,1000,1,20,4,20,1105,1,46,98,99
diff --git a/src/day5/ElfComputer3.php b/src/day5/ElfComputer3.php
new file mode 100644
index 0000000..a1581ab
--- /dev/null
+++ b/src/day5/ElfComputer3.php
@@ -0,0 +1,178 @@
+<?php
+
+namespace PuzzleSolvers\Day5;
+
+use PuzzleSolvers\PuzzleSolver;
+
+class ElfComputer3 extends PuzzleSolver
+{
+    public $program;
+    public $position;
+    public $input;
+    public $outputs;
+    public $parameterMode;
+    public $instructionLength = 4;
+
+    public function initialise()
+    {
+        $this->position = 0;
+        $this->program = array_map('intval', explode(',', $this->inputs[0]));
+        $this->outputs = [];
+    }
+
+    public function run()
+    {
+        while ($this->position < $this->getProgramSize()) {
+            $instruction = $this->parseInstruction($this->readMemory());
+            $this->execute($instruction);
+        }
+
+        $this->output = implode(',', $this->program);
+    }
+
+    public function parseInstruction($instruction)
+    {
+        $parsedInstuction = [];
+        $parsedInstuction['opcode'] = (int) substr($instruction, -2, 2);
+        $parsedInstuction['mode1'] = (strlen($instruction) > 2) ? (int) substr($instruction, -3, 1) : 0;
+        $parsedInstuction['mode2'] = (strlen($instruction) > 3) ? (int) substr($instruction, -4, 1) : 0;
+        $parsedInstuction['mode3'] = (strlen($instruction) > 4) ? (int) substr($instruction, -5, 1) : 0;
+
+        return $parsedInstuction;
+    }
+
+    public function getParameter(int $offset, int $mode)
+    {
+        $parameter = $this->readMemoryOffset($offset);
+        if ($mode == 0) {
+            $parameter = $this->readMemory($parameter);
+        }
+
+        return $parameter;
+    }
+
+    public function execute($instruction)
+    {
+        $opcode = $instruction['opcode'];
+
+        if ($opcode === 1) {
+            $parameter1 = $this->getParameter(1, $instruction['mode1']);
+            $parameter2 = $this->getParameter(2, $instruction['mode2']);
+            $parameter3 = $this->readMemoryOffset(3);
+            $value = $parameter1 + $parameter2;
+            $this->writeMemory($value, $parameter3);
+            $this->position += 4;
+        }
+
+         else if ($opcode === 2) {
+            $parameter1 = $this->getParameter(1, $instruction['mode1']);
+            $parameter2 = $this->getParameter(2, $instruction['mode2']);
+            $parameter3 = $this->readMemoryOffset(3);
+            $value = $parameter1 * $parameter2;
+            $this->writeMemory($value, $parameter3);
+            $this->position += 4;
+        }
+
+        else if ($opcode == 3) {
+            $this->writeMemory($this->input, $this->readMemoryOffset(1));
+            $this->position += 2;
+        }
+
+        else if ($opcode == 4) {
+            $parameter1 = $this->getParameter(1, $instruction['mode1']);
+            $this->outputs[] = $parameter1;
+            $this->position += 2;
+        }
+
+        else if ($opcode == 5) {
+            $parameter1 = $this->getParameter(1, $instruction['mode1']);
+            $parameter2 = $this->getParameter(2, $instruction['mode2']);
+            if ($parameter1 != 0) {
+                $this->position = $parameter2;
+            } else {
+                $this->position += 3;
+            }
+        }
+
+        else if ($opcode == 6) {
+            $parameter1 = $this->getParameter(1, $instruction['mode1']);
+            $parameter2 = $this->getParameter(2, $instruction['mode2']);
+            if ($parameter1 == 0) {
+                $this->position = $parameter2;
+            } else {
+                $this->position += 3;
+            }
+        }
+
+        else if ($opcode == 7) {
+            $parameter1 = $this->getParameter(1, $instruction['mode1']);
+            $parameter2 = $this->getParameter(2, $instruction['mode2']);
+            $parameter3 = $this->readMemoryOffset(3);
+            $value = ($parameter1 < $parameter2) ? 1 : 0;
+            $this->writeMemory($value, $parameter3);
+            $this->position += 4;
+        }
+
+        else if ($opcode == 8) {
+            $parameter1 = $this->getParameter(1, $instruction['mode1']);
+            $parameter2 = $this->getParameter(2, $instruction['mode2']);
+            $parameter3 = $this->readMemoryOffset(3);
+            $value = ($parameter1 == $parameter2) ? 1 : 0;
+            $this->writeMemory($value, $parameter3);
+            $this->position += 4;
+        }
+
+        else if ($opcode === 99) {
+            $this->position = $this->getProgramSize();
+        } else {
+            $this->position += 1;
+        }
+    }
+
+    public function getProgramSize(): int
+    {
+        return count($this->program);
+    }
+
+    public function readMemory($position = null)
+    {
+        if (is_null($position)) {
+            $position = $this->position;
+        }
+
+        return $this->program[$position];
+    }
+
+    public function readMemoryOffset($offset = 0)
+    {
+        return $this->program[$this->position + $offset];
+    }
+
+    public function writeMemoryOffset(int $value, $offset = 0)
+    {
+        $this->program[$this->position + $offset] = $value;
+    }
+
+    public function writeMemory(int $value, $position = null)
+    {
+        if (is_null($position)) {
+            $position = $this->position;
+        }
+        $this->program[$position] = $value;
+    }
+
+    public function getProgram(): array
+    {
+        return $this->program ?: [];
+    }
+
+    public function getPosition(): int
+    {
+        return $this->position ?: 0;
+    }
+
+    public function setPosition(int $position): void
+    {
+        $this->position = $position;
+    }
+}
diff --git a/src/day5/solve.php b/src/day5/solve.php
index 0e775d5..6214bb2 100644
--- a/src/day5/solve.php
+++ b/src/day5/solve.php
@@ -3,6 +3,7 @@
 require_once __DIR__ . '/../../vendor/autoload.php';
 
 use PuzzleSolvers\Day5\ElfComputer2;
+use PuzzleSolvers\Day5\ElfComputer3;
 
 $elfComputer = new ElfComputer2('day5/part1/input');
 $elfComputer->initialise();
@@ -11,3 +12,11 @@
 $outputs = $elfComputer->outputs;
 
 echo "Day 5 Part 1 answer: " . end($outputs) . "\n";
+
+$elfComputer = new ElfComputer3('day5/part1/input');
+$elfComputer->initialise();
+$elfComputer->input = 5;
+$elfComputer->run();
+$outputs = $elfComputer->outputs;
+
+echo "Day 5 Part 2 answer: " . end($outputs) . "\n";
diff --git a/tests/Day5Part2Test.php b/tests/Day5Part2Test.php
new file mode 100644
index 0000000..55f70b8
--- /dev/null
+++ b/tests/Day5Part2Test.php
@@ -0,0 +1,166 @@
+<?php
+
+use PHPUnit\Framework\TestCase;
+use PuzzleSolvers\Day5\ElfComputer3;
+
+final class Day5Part2Test extends TestCase
+{
+    public function testDay2EndToEnd(): void
+    {
+        $outputs = [
+            '3500,9,10,70,2,3,11,0,99,30,40,50',
+            '2,0,0,0,99',
+            '2,3,0,6,99',
+            '2,4,4,5,99,9801',
+            '30,1,1,4,2,5,6,0,99',
+        ];
+        foreach ($outputs as $inputFileNumber => $output) {
+            $puzzleSolver = new ElfComputer3('day2/part1/' . $inputFileNumber);
+            $puzzleSolver->initialise();
+            $puzzleSolver->run();
+            $this->assertSame($output, $puzzleSolver->getOutput());
+        }
+    }
+
+    public function testInitialiseLoadsInputToProgramAndSetsPositionTo0(): void
+    {
+        $elfComputer = new ElfComputer3('day2/part1/0');
+
+        $elfComputer->initialise();
+
+        $this->assertSame([1, 9, 10, 3, 2, 3, 11, 0, 99, 30, 40, 50], $elfComputer->getProgram());
+        $this->assertSame(0, $elfComputer->getPosition());
+    }
+
+    public function testPart1EndToEnd()
+    {
+        $outputs = [
+            [42, 0, 4, 0, 99],
+            [1002, 4, 3, 4, 99],
+            [1101, 100, -1, 4, 99],
+        ];
+        $programOutput = [
+            [42],
+            [],
+            [],
+        ];
+        foreach ($outputs as $inputFileNumber => $output) {
+            $elfComputer = new ElfComputer3('day5/part1/' . $inputFileNumber);
+            $elfComputer->initialise();
+            $elfComputer->input = 42;
+            $elfComputer->run();
+
+            $this->assertSame($programOutput[$inputFileNumber], $elfComputer->outputs);
+            $this->assertSame($outputs[$inputFileNumber], $elfComputer->program);
+        }
+    }
+
+    public function testEndToEnd()
+    {
+        $outputs = [
+            [0],
+            [1],
+            [0],
+            [0],
+            [1],
+            [0],
+            [1],
+            [0],
+            [1],
+            [999],
+            [1000],
+            [1001],
+        ];
+        $inputs = [
+            7,
+            8,
+            9,
+            8,
+            7,
+            55,
+            8,
+            8,
+            7,
+            7,
+            8,
+            9,
+        ];
+        foreach ($outputs as $inputFileNumber => $output) {
+            \PuzzleDebugger::print('TESTING FILE: ' . $inputFileNumber);
+            $elfComputer = new ElfComputer3('day5/part2/' . $inputFileNumber);
+            $elfComputer->initialise();
+            $elfComputer->input = $inputs[$inputFileNumber];
+            $elfComputer->run();
+
+            $this->assertSame($outputs[$inputFileNumber], $elfComputer->outputs);
+        }
+    }
+
+    public function testReadMemory(): void
+    {
+        $elfComputer = new ElfComputer3('day2/part1/0');
+        $elfComputer->initialise();
+        $elfComputer->setPosition(1);
+
+        $value0 = $elfComputer->readMemory(0);
+        $this->assertSame(1, $value0);
+
+        $value1 = $elfComputer->readMemory();
+        $this->assertSame(9, $value1);
+
+        $value2 = $elfComputer->readMemory(2);
+        $this->assertSame(10, $value2);
+    }
+
+    public function testReadMemoryOffset(): void
+    {
+        $elfComputer = new ElfComputer3('day2/part1/0');
+        $elfComputer->initialise();
+        $elfComputer->setPosition(1);
+
+        $value1 = $elfComputer->readMemoryOffset(0);
+        $this->assertSame(9, $value1);
+
+        $value3 = $elfComputer->readMemoryOffset(2);
+        $this->assertSame(3, $value3);
+    }
+
+    public function testWriteMemory(): void
+    {
+        $elfComputer = new ElfComputer3('day2/part1/0');
+        $elfComputer->initialise();
+        $elfComputer->setPosition(1);
+
+        $elfComputer->writeMemory(5, 0);
+        $elfComputer->writeMemory(42);
+
+        $program = $elfComputer->getProgram();
+        $this->assertSame(5, $program[0]);
+        $this->assertSame(42, $program[1]);
+    }
+
+    public function testWriteMemoryOffset(): void
+    {
+        $elfComputer = new ElfComputer3('day2/part1/0');
+        $elfComputer->initialise();
+        $elfComputer->setPosition(1);
+
+        $elfComputer->writeMemoryOffset(5, 2);
+        $elfComputer->writeMemoryOffset(42);
+
+        $program = $elfComputer->getProgram();
+        $this->assertSame(5, $program[3]);
+        $this->assertSame(42, $program[1]);
+    }
+
+    public function testParseInstruction()
+    {
+        $elfComputer = new ElfComputer3('day5/part1/0');
+        $parsedInstruction = $elfComputer->parseInstruction('1002');
+
+        $this->assertSame(2, $parsedInstruction['opcode']);
+        $this->assertSame(0, $parsedInstruction['mode1']);
+        $this->assertSame(1, $parsedInstruction['mode2']);
+        $this->assertSame(0, $parsedInstruction['mode3']);
+    }
+}