diff --git a/src/app/(protected)/workorders/_components/wizard/wizard-step-type-schedule.tsx b/src/app/(protected)/workorders/_components/wizard/wizard-step-type-schedule.tsx
index f4df71a3..96f2a62d 100644
--- a/src/app/(protected)/workorders/_components/wizard/wizard-step-type-schedule.tsx
+++ b/src/app/(protected)/workorders/_components/wizard/wizard-step-type-schedule.tsx
@@ -262,9 +262,23 @@ export function WizardStepTypeSchedule({
         <WoTypePicker
           selected={draft.type}
           onSelect={(t) => {
+            const typeChanged = t !== draft.type;
             onPatch({
               type: t,
               severity: nextSeverityForType(draft.type, t, draft.severity),
+              // A registry service is scoped to its work-order type, so a service picked
+              // under the previous type fails backend ResolveServiceAsync (SH-187/#131).
+              // Clear the service (and its vendor, filtered by the service) on a type change.
+              ...(typeChanged
+                ? {
+                    pm: "",
+                    serviceId: null,
+                    extraServices: [],
+                    vendorId: "",
+                    vendorName: "",
+                    techPhone: "",
+                  }
+                : {}),
             });
           }}
         />
diff --git a/src/test/app/(protected)/workorders/wizard-step-type-schedule-clears-service.test.tsx b/src/test/app/(protected)/workorders/wizard-step-type-schedule-clears-service.test.tsx
new file mode 100644
index 00000000..9c9582ee
--- /dev/null
+++ b/src/test/app/(protected)/workorders/wizard-step-type-schedule-clears-service.test.tsx
@@ -0,0 +1,69 @@
+import { fireEvent, render, screen } from "@testing-library/react";
+import { describe, expect, it, vi } from "vitest";
+import { WizardStepTypeSchedule } from "@/app/(protected)/workorders/_components/wizard/wizard-step-type-schedule";
+import {
+  EMPTY_WIZARD_DRAFT,
+  type WorkOrderWizardDraft,
+} from "@/domain/work-orders/types/work-order-wizard";
+
+const USERS = [{ id: "sarah", name: "Sarah Chen" }];
+
+describe("WizardStepTypeSchedule — service clear on type change", () => {
+  it("clears the service and its vendor when the work-order type changes", () => {
+    const onPatch = vi.fn();
+    const draft: WorkOrderWizardDraft = {
+      ...EMPTY_WIZARD_DRAFT,
+      type: "PM",
+      pm: "HVAC",
+      serviceId: "1",
+      extraServices: ["Plumbing"],
+      vendorId: "9",
+      vendorName: "Old Vendor",
+      techPhone: "555-0100",
+    };
+
+    render(
+      <WizardStepTypeSchedule draft={draft} users={USERS} onUpdate={vi.fn()} onPatch={onPatch} />,
+    );
+
+    fireEvent.click(screen.getByRole("button", { name: /Reactive/ }));
+
+    expect(onPatch).toHaveBeenCalledWith(
+      expect.objectContaining({
+        type: "Reactive",
+        pm: "",
+        serviceId: null,
+        extraServices: [],
+        vendorId: "",
+        vendorName: "",
+        techPhone: "",
+      }),
+    );
+  });
+
+  it("keeps the selected service when the same type is re-selected", () => {
+    const onPatch = vi.fn();
+    const draft: WorkOrderWizardDraft = {
+      ...EMPTY_WIZARD_DRAFT,
+      type: "PM",
+      pm: "HVAC",
+      serviceId: "1",
+      extraServices: ["Plumbing"],
+      vendorId: "9",
+      vendorName: "Old Vendor",
+      techPhone: "555-0100",
+    };
+
+    render(
+      <WizardStepTypeSchedule draft={draft} users={USERS} onUpdate={vi.fn()} onPatch={onPatch} />,
+    );
+
+    fireEvent.click(screen.getByRole("button", { name: /Scheduled preventive maintenance/ }));
+
+    const patch = onPatch.mock.calls[0][0] as Partial<WorkOrderWizardDraft>;
+    expect(patch).not.toHaveProperty("pm");
+    expect(patch).not.toHaveProperty("serviceId");
+    expect(patch).not.toHaveProperty("extraServices");
+    expect(patch).not.toHaveProperty("vendorId");
+  });
+});