diff --git a/csaf_2_1/recommendedTests/recommendedTest_6_2_16.js b/csaf_2_1/recommendedTests/recommendedTest_6_2_16.js
index 30db99f7..d78261f6 100644
--- a/csaf_2_1/recommendedTests/recommendedTest_6_2_16.js
+++ b/csaf_2_1/recommendedTests/recommendedTest_6_2_16.js
@@ -1,8 +1,137 @@
-import { optionalTest_6_2_16 } from '../../optionalTests.js'
+import { Ajv } from 'ajv/dist/jtd.js'
+
+const ajv = new Ajv()
+
+const inputSchema = /** @type {const} */ ({
+  additionalProperties: true,
+  optionalProperties: {
+    product_tree: {
+      additionalProperties: true,
+      optionalProperties: {
+        branches: {
+          elements: { additionalProperties: true, properties: {} },
+        },
+        full_product_names: {
+          elements: { additionalProperties: true, properties: {} },
+        },
+        product_paths: {
+          elements: { additionalProperties: true, properties: {} },
+        },
+      },
+    },
+  },
+})
+
+const branchSchema = /** @type {const} */ ({
+  additionalProperties: true,
+  optionalProperties: {
+    branches: {
+      elements: {
+        additionalProperties: true,
+        properties: {},
+      },
+    },
+    product: {
+      additionalProperties: true,
+      optionalProperties: {
+        product_identification_helper: {
+          additionalProperties: true,
+          properties: {},
+        },
+      },
+    },
+  },
+})
+
+const productPathSchema = /** @type {const} */ ({
+  additionalProperties: true,
+  optionalProperties: {
+    full_product_name: {
+      additionalProperties: true,
+      optionalProperties: {
+        product_identification_helper: {
+          additionalProperties: true,
+          properties: {},
+        },
+      },
+    },
+  },
+})
+
+const validateInput = ajv.compile(inputSchema)
+const validateBranch = ajv.compile(branchSchema)
+const validateProductPath = ajv.compile(productPathSchema)
 
 /**
- * @param {unknown} doc
+ * @param {any} doc
  */
 export function recommendedTest_6_2_16(doc) {
-  return optionalTest_6_2_16(doc)
+  const ctx = {
+    warnings:
+      /** @type {Array<{ instancePath: string; message: string }>} */ ([]),
+  }
+
+  if (!validateInput(doc)) {
+    return ctx
+  }
+
+  doc.product_tree?.full_product_names?.forEach(
+    (fullProductName, fullProductNameIndex) => {
+      if (!fullProductName.product_identification_helper) {
+        ctx.warnings.push({
+          instancePath: `/product_tree/full_product_names/${fullProductNameIndex}`,
+          message: 'missing product identification helper',
+        })
+      }
+    }
+  )
+
+  /**
+   * @param {object} params
+   * @param {string} params.path
+   * @param {unknown[]} params.branches
+   */
+  function checkBranches({ path, branches }) {
+    branches.forEach((branch, branchIndex) => {
+      if (!validateBranch(branch)) {
+        return
+      }
+      if (branch.product && !branch.product.product_identification_helper) {
+        ctx.warnings.push({
+          instancePath: `${path}/${branchIndex}/product`,
+          message: 'missing product identification helper',
+        })
+      }
+      if (Array.isArray(branch.branches)) {
+        checkBranches({
+          path: `${path}/${branchIndex}/branches`,
+          branches: branch.branches,
+        })
+      }
+    })
+  }
+
+  if (doc.product_tree?.branches) {
+    checkBranches({
+      path: '/product_tree/branches',
+      branches: doc.product_tree.branches,
+    })
+  }
+
+  doc.product_tree?.product_paths?.forEach((productPath, productPathIndex) => {
+    if (!validateProductPath(productPath)) {
+      return
+    }
+    if (
+      productPath.full_product_name &&
+      !productPath.full_product_name.product_identification_helper
+    ) {
+      ctx.warnings.push({
+        instancePath: `/product_tree/product_paths/${productPathIndex}/full_product_name`,
+        message: 'missing product identification helper',
+      })
+    }
+  })
+
+  return ctx
 }
diff --git a/tests/csaf_2_1/recommendedTest_6_2_16.js b/tests/csaf_2_1/recommendedTest_6_2_16.js
new file mode 100644
index 00000000..78639e7d
--- /dev/null
+++ b/tests/csaf_2_1/recommendedTest_6_2_16.js
@@ -0,0 +1,56 @@
+import assert from 'node:assert'
+import { recommendedTest_6_2_16 } from '../../csaf_2_1/recommendedTests.js'
+
+describe('recommendedTest_6_2_16', function () {
+  it('only runs on relevant documents', function () {
+    assert.equal(
+      recommendedTest_6_2_16({ vulnerabilities: 'mydoc' }).warnings.length,
+      0
+    )
+  })
+
+  it('returns no warnings for invalid inputSchema (product_tree is not an object)', function () {
+    const result = recommendedTest_6_2_16({
+      product_tree: 'not-an-object',
+    })
+    assert.equal(result.warnings.length, 0)
+  })
+
+  it('skips invalid branch entries and does not throw', function () {
+    const result = recommendedTest_6_2_16({
+      product_tree: {
+        branches: [{ product: 'not-an-object' }],
+      },
+    })
+    assert.equal(result.warnings.length, 0)
+  })
+
+  it('skips invalid product_paths entries and does not throw', function () {
+    const result = recommendedTest_6_2_16({
+      product_tree: {
+        product_paths: [{ full_product_name: 'not-an-object' }],
+      },
+    })
+    assert.equal(result.warnings.length, 0)
+  })
+
+  it('warns when a product_paths entry is missing product_identification_helper', function () {
+    const result = recommendedTest_6_2_16({
+      product_tree: {
+        product_paths: [
+          {
+            full_product_name: {
+              name: 'Product A',
+              product_id: 'CSAFPID-0001',
+            },
+          },
+        ],
+      },
+    })
+    assert.equal(result.warnings.length, 1)
+    assert.equal(
+      result.warnings[0].instancePath,
+      '/product_tree/product_paths/0/full_product_name'
+    )
+  })
+})