diff --git a/tests/unit/handlers/coolingSystem.handlers.test.js b/tests/unit/handlers/coolingSystem.handlers.test.js
index 3b88359..71614c6 100644
--- a/tests/unit/handlers/coolingSystem.handlers.test.js
+++ b/tests/unit/handlers/coolingSystem.handlers.test.js
@@ -1409,6 +1409,30 @@ test('6 - differential_pressure populated when per-group PTs configured', (t) =>
   t.pass()
 })
 
+test('6 - differential_pressure from single-transmitter array (supply/return/diff)', (t) => {
+  const equipment = createMockEquipment()
+  equipment.pressures = [
+    ...equipment.pressures,
+    { equipment: 'PT-7502-A', value: 2.81, unit: 'bar', supply_pressure: 2.81, return_pressure: 2.2, differential_pressure: 0.61 },
+    { equipment: 'PT-7502-B', value: 2.9, unit: 'bar', supply_pressure: 2.9, return_pressure: 2.3 }
+  ]
+  const config = createMockConfig()
+  config.cooling_system.miner_loop.line1.group_pressure_sensors = ['PT-7502-A', 'PT-7502-B']
+  const view = buildMinersCircuit1View(equipment, config)
+
+  const dp = view.lines[0].differential_pressure
+  t.is(dp.length, 2, 'one row per transmitter')
+  // Group 1: device-provided differential is preferred
+  t.is(dp[0].supply.tag, 'PT-7502-A', 'supply tag = transmitter id')
+  t.is(dp[0].return.tag, 'PT-7502-A', 'return tag = same transmitter id')
+  t.is(dp[0].supply.reading.value, 2.81, 'supply from supply_pressure')
+  t.is(dp[0].return.reading.value, 2.2, 'return from return_pressure')
+  t.is(dp[0].delta_p.value, 0.61, 'uses device-provided differential_pressure')
+  // Group 2: no device differential -> derived from supply - return
+  t.is(dp[1].delta_p.value, 0.6, 'derived delta-p = supply - return when DP absent')
+  t.pass()
+})
+
 test('7 - rack_statuses derived from live rack power (online = power > 0)', (t) => {
   const equipment = createMockEquipment()
   const config = createMockConfig()
diff --git a/workers/lib/server/handlers/cooling.system.handlers.js b/workers/lib/server/handlers/cooling.system.handlers.js
index fc0d328..f26b8ec 100644
--- a/workers/lib/server/handlers/cooling.system.handlers.js
+++ b/workers/lib/server/handlers/cooling.system.handlers.js
@@ -76,6 +76,34 @@ function buildVibrationSwitch (vibrationSwitches, switchTag) {
 
 function buildGroupDifferentialPressure (lineConfig, pressures) {
   const groupSensors = lineConfig.group_pressure_sensors || {}
+
+  if (Array.isArray(groupSensors)) {
+    return groupSensors.map((sensorId, i) => {
+      const pt = pressures?.find(s => s.equipment === sensorId) || null
+      const mkSlot = (val) => ({
+        tag: sensorId,
+        type: pt?.type || null,
+        reading: val != null ? { value: val, unit: pt?.unit || 'bar' } : null
+      })
+      const supply = mkSlot(pt?.supply_pressure)
+      const ret = mkSlot(pt?.return_pressure)
+      const supplyVal = supply.reading?.value
+      const returnVal = ret.reading?.value
+      const deltaPVal = pt?.differential_pressure != null
+        ? Math.round(pt.differential_pressure * 100) / 100
+        : (supplyVal != null && returnVal != null
+            ? Math.round((supplyVal - returnVal) * 100) / 100
+            : null)
+      const unit = supply.reading?.unit || ret.reading?.unit || pt?.unit || 'bar'
+      return {
+        group: i + 1,
+        supply,
+        return: ret,
+        delta_p: deltaPVal != null ? { value: deltaPVal, unit } : null
+      }
+    })
+  }
+
   const supplyIds = groupSensors.supply || []
   const returnIds = groupSensors.return || []
   const count = Math.max(supplyIds.length, returnIds.length)