diff --git a/src/composables/useSelfServeLogic.js b/src/composables/useSelfServeLogic.js
index 66038881..c800661f 100644
--- a/src/composables/useSelfServeLogic.js
+++ b/src/composables/useSelfServeLogic.js
@@ -498,6 +498,10 @@ export function useSelfServeLogic() {
     machineType.value = previewData?.machine_type || machineType.value;
     vehicle.value = previewData?.vehicle || null;
     session.value = previewData?.session || session.value;
+    if (!previewData?.session?.id) {
+      summary.value = null;
+      events.value = [];
+    }
     if (Object.prototype.hasOwnProperty.call(previewData || {}, "config_version_id")) {
       configVersionId.value = previewData?.config_version_id ?? null;
     }
diff --git a/tests/unit/use-self-serve-logic.spec.js b/tests/unit/use-self-serve-logic.spec.js
index 1821ea0a..f6d7ec14 100644
--- a/tests/unit/use-self-serve-logic.spec.js
+++ b/tests/unit/use-self-serve-logic.spec.js
@@ -91,6 +91,52 @@ describe("useSelfServeLogic", () => {
     });
   });
 
+  it("clears stale wash summary machine availability when a fresh preview has no session", async () => {
+    mocks.previewAllowed
+      .mockResolvedValueOnce({
+        allowed: true,
+        machine_available: true,
+        lane: { id: 7, name: "Lane 7" },
+        session: { id: 91, status: "READY_FOR_MACHINE_START" },
+        questions: [{ id: 1, question: "Machine wash?", answer: true, order_priority: 1 }],
+        tasks: [{ id: 5, task: "Prepare", order_priority: 1, services: ["MACHINE"] }],
+        conditions: [],
+        rules: [],
+        allowed_services: ["MACHINE"],
+      })
+      .mockResolvedValueOnce({
+        allowed: true,
+        machine_available: true,
+        lane: { id: 7, name: "Lane 7" },
+        session: null,
+        questions: [{ id: 1, question: "Machine wash?", answer: true, order_priority: 1 }],
+        tasks: [{ id: 5, task: "Prepare", order_priority: 1, services: ["MACHINE"] }],
+        conditions: [],
+        rules: [],
+        allowed_services: ["MACHINE"],
+      });
+    mocks.washSummary.mockResolvedValueOnce({
+      machine_available: false,
+      session: { id: 91, status: "READY_FOR_MACHINE_START" },
+      lane: { id: 7, name: "Lane 7" },
+      questions: [{ id: 1, question: "Machine wash?", answer: true, order_priority: 1 }],
+      tasks: [{ id: 5, task: "Prepare", order_priority: 1, services: ["MACHINE"] }],
+      events: [],
+      allowed_services: [],
+    });
+
+    const logic = useSelfServeLogic();
+
+    await logic.fetchSelfServeData(1, 9, 7, "ab12345");
+    expect(logic.machineAvailable.value).toBe(false);
+
+    await logic.fetchSelfServeData(1, 9, 7, "cd12345");
+
+    expect(logic.summary.value).toBeNull();
+    expect(logic.machineAvailable.value).toBe(true);
+    expect(logic.allowedServices.value).toEqual(["MACHINE"]);
+  });
+
   it("preserves preview task ids when wash summary omits task ids", async () => {
     mocks.previewAllowed.mockResolvedValue({
       allowed: true,