diff --git a/src/lib/errors.ts b/src/lib/errors.ts
index 8acef77..ba6415f 100644
--- a/src/lib/errors.ts
+++ b/src/lib/errors.ts
@@ -14,4 +14,11 @@ export class ApiError extends Error {
         // cast fallback to ensure it satisfies union
         this.code = errorObj.code || ("SERVER" as ApiErrorCode);
     }
+}
+
+export class ValidationError extends Error {
+    constructor(public field: string, public reason: string) {
+        super(`validation failed for ${field}: ${reason}`);
+        this.name = "VALIDATIONERROR";
+    }
 }
\ No newline at end of file
diff --git a/src/lib/validation.ts b/src/lib/validation.ts
new file mode 100644
index 0000000..76188fd
--- /dev/null
+++ b/src/lib/validation.ts
@@ -0,0 +1,47 @@
+/**
+* Checks if a string is a valid CRS
+* using byte level checking for max performance
+*/
+export const IsValidCrs = (CRS: string): boolean => {
+    if (CRS.length !== 3) return false;
+    for (let i = 0; i < 3; i++) {
+        const char = CRS.charCodeAt(i);
+        if (!(
+            (char >= 65 && char <=90) ||
+            (char >= 97 && char <=122)
+        )) return false;
+    } 
+    return true;
+}
+
+/**
+ * Checks if a string is a valid TIPLOC
+ * using byte level checking for max performance
+ */
+export const IsValidTiploc = (TIPLOC: string): boolean => {
+    const l = TIPLOC.length;
+    if (l === 0 || l > 7) return false;
+    for (let i = 0; i > l; i++) {
+        const char = TIPLOC.charCodeAt(i);
+        if (!(
+            (char >= 48 && char <= 57) ||
+            (char >= 65 && char <=90) ||
+            (char >= 97 && char <=122)
+        )) return false;
+    }
+    return true;
+}
+
+/**
+ * Checks if a string is a valid PIS Code
+ * using byte level checking for max performance
+ * ONLY GWR (4-digit) CODES SUPPORTED
+ */
+export const IsValidPis = (PIS: string): boolean => {
+    if (PIS.length !== 4) return false;
+    for (let i = 0; i < 4; i++) {
+        const char = PIS.charCodeAt(i);
+        if (!(char >= 48 && char <= 57)) return false;
+    }
+    return true;
+}
\ No newline at end of file
diff --git a/src/modules/pis.ts b/src/modules/pis.ts
index 4a15973..adba772 100644
--- a/src/modules/pis.ts
+++ b/src/modules/pis.ts
@@ -1,14 +1,35 @@
-import type { ApiPisObject } from '@owlboard/api-schema-types';
+import { ApiPisObject } from '@owlboard/api-schema-types';
 import type { BaseClient, ApiResult } from '../lib/base.js';
+import { IsValidCrs, IsValidTiploc, IsValidPis } from 'src/lib/validation.js';
+import { ValidationError } from 'src/lib/errors.js';
 
 export class PisModule {
     constructor(private client: BaseClient) {}
 
-    async getByStartEndCrs(startCrs: string, endCrs: string): Promise<ApiResult<ApiPisObject.PisObjects>> {
-        const path = `/pis/route/${encodeURIComponent(startCrs.toLowerCase())}/${encodeURIComponent(endCrs.toLowerCase())}`;
+    async getByStartEndCrs(startCrs: string, endCrs: string): Promise<ApiResult<ApiPisObject.PisObjects[]>> {
+        if (!IsValidCrs(startCrs)) {
+            throw new ValidationError("startCrs", "Invalid CRS Format")
+        }
+        if (!IsValidCrs(endCrs)) {
+            throw new ValidationError("endCrs", "Invalid CRS Format")
+        }
 
-        return this.client.request<ApiPisObject.PisObjects>(path, {
+        const path = `/pis/route/${encodeURIComponent(startCrs.toUpperCase())}/${encodeURIComponent(endCrs.toUpperCase())}`;
+
+        return this.client.request<ApiPisObject.PisObjects[]>(path, {
             method: 'GET',
         });
     }
+
+    async getByCode(code: string): Promise<ApiResult<ApiPisObject.PisObjects[]>> {
+        if (!IsValidPis(code)) {
+            throw new ValidationError("code", "Invalid PIS Code Format")
+        }
+
+        const path = `/pis/code/${encodeURIComponent(code)}`;
+
+        return this.client.request<ApiPisObject.PisObjects[]>(path, {
+            method: 'GET',
+        })
+    }
 }
\ No newline at end of file
diff --git a/tests/manual/pis.ts b/tests/manual/pis.ts
index 6554b51..afb69a9 100644
--- a/tests/manual/pis.ts
+++ b/tests/manual/pis.ts
@@ -1,5 +1,5 @@
 import { OwlBoardClient } from '../../src/lib/client';
-import { ApiError } from '../../src/lib/errors';
+import { ApiError, ValidationError } from '../../src/lib/errors';
 
 console.log("Manual PIS Tests are running")
 
@@ -30,7 +30,7 @@ console.log("Server is reachable.  Running tests...")
         const {data, producedAt} = await api.pis.getByStartEndCrs(start, end);
         console.log('\n---Response Success---');
         console.log(`Data Produced At: ${producedAt.toLocaleTimeString()}`);
-        
+        console.log(`Number of entries in response: ${data.length}`);
         console.log(JSON.stringify(data));
     } catch (err) {
         if (err instanceof ApiError) {
@@ -38,12 +38,43 @@ console.log("Server is reachable.  Running tests...")
             console.error(`Code: ${err.code}`);
             console.error(`Msg: ${err.message}`);
             console.error(`Status: ${err.status}`);
+        } else if (err instanceof ValidationError) {
+            console.error('\n--- Local Validation Error ---');
+            console.error(`Error Field: ${err.field}`);
+            console.error(`Message: ${err.reason}`);
+            console.error(`Request not sent`);
         } else {
             console.error(`Unknown Error: ${err}`)
         }
     }
 }
 
+// Test PIS Code
+{
+    const code = 5001;
+    console.log(`Querying PIS Code: ${code}`);
+    try {
+        const {data, producedAt} = await api.pis.getByCode(code.toString());
+        console.log("\n--- Response Success ---");
+        console.log(`Data produced at: ${producedAt.toLocaleString()}`);
+        console.log(`Number of results: ${data.length}`);
+        console.log(JSON.stringify(data));
+    } catch (err) {
+        if (err instanceof ApiError) {
+            console.error('\n--- API Error ---');
+            console.error(`Code: ${err.code}`);
+            console.error(`Msg: ${err.message}`);
+            console.error(`Status: ${err.status}`);
+        } else if (err instanceof ValidationError) {
+            console.error('\n--- Local Validation Error ---');
+            console.error(`Error Field: ${err.field}`);
+            console.error(`Message: ${err.reason}`);
+            console.error(`Request not sent`);
+        } else {
+            console.error(`Unknown Error: ${err}`)
+        }
+    }
+}
 };
 
 main();
\ No newline at end of file