diff --git a/packages/core-utils/src/__tests__/__snapshots__/query.js.snap b/packages/core-utils/src/__tests__/__snapshots__/query.js.snap
index 8d52797df..76b93a2e2 100644
--- a/packages/core-utils/src/__tests__/__snapshots__/query.js.snap
+++ b/packages/core-utils/src/__tests__/__snapshots__/query.js.snap
@@ -60,6 +60,58 @@ Object {
 }
 `;
 
+exports[`query getRoutingParams should create repaired routing params for broken flex query 1`] = `
+Object {
+  "arriveBy": false,
+  "date": "2020-08-24",
+  "fromPlace": "Steamer Lane, Santa Cruz, CA, 95060, USA::36.95471026341096,-122.0248185852425",
+  "ignoreRealtimeUpdates": false,
+  "maxWalkDistance": 1207,
+  "mode": "WALK,FLEX_EGRESS,FLEX_ACCESS,FLEX_DIRECT,TRANSIT",
+  "numItineraries": 3,
+  "optimize": "QUICK",
+  "otherThanPreferredRoutesPenalty": 900,
+  "showIntermediateStops": true,
+  "time": "21:53",
+  "toPlace": "Municipal Wharf St, Santa Cruz, CA, 95060, USA::36.961843106786766,-122.02402657342725",
+  "walkSpeed": 1.34,
+}
+`;
+
+exports[`query getRoutingParams should create repaired routing params for very broken flex query 1`] = `
+Object {
+  "arriveBy": false,
+  "date": "2020-08-24",
+  "fromPlace": "Steamer Lane, Santa Cruz, CA, 95060, USA::36.95471026341096,-122.0248185852425",
+  "ignoreRealtimeUpdates": false,
+  "mode": "FLEX_EGRESS,FLEX_ACCESS,FLEX_DIRECT,WALK,BIKE",
+  "numItineraries": 3,
+  "otherThanPreferredRoutesPenalty": 900,
+  "showIntermediateStops": true,
+  "time": "21:53",
+  "toPlace": "Municipal Wharf St, Santa Cruz, CA, 95060, USA::36.961843106786766,-122.02402657342725",
+  "walkSpeed": 1.34,
+}
+`;
+
+exports[`query getRoutingParams should create repaired routing params for very broken flex query 2`] = `
+Object {
+  "arriveBy": false,
+  "date": "2020-08-24",
+  "fromPlace": "Steamer Lane, Santa Cruz, CA, 95060, USA::36.95471026341096,-122.0248185852425",
+  "ignoreRealtimeUpdates": false,
+  "maxWalkDistance": 1207,
+  "mode": "FLEX_EGRESS,FLEX_ACCESS,FLEX_DIRECT,WALK,BIKE,WALK,TRANSIT,BUS",
+  "numItineraries": 3,
+  "optimize": "QUICK",
+  "otherThanPreferredRoutesPenalty": 900,
+  "showIntermediateStops": true,
+  "time": "21:53",
+  "toPlace": "Municipal Wharf St, Santa Cruz, CA, 95060, USA::36.961843106786766,-122.02402657342725",
+  "walkSpeed": 1.34,
+}
+`;
+
 exports[`query getRoutingParams should create routing params for car rental query 1`] = `
 Object {
   "arriveBy": false,
@@ -80,6 +132,21 @@ Object {
 }
 `;
 
+exports[`query getRoutingParams should create routing params for flex-only query 1`] = `
+Object {
+  "arriveBy": false,
+  "date": "2020-08-24",
+  "fromPlace": "Steamer Lane, Santa Cruz, CA, 95060, USA::36.95471026341096,-122.0248185852425",
+  "ignoreRealtimeUpdates": false,
+  "mode": "FLEX_EGRESS,FLEX_ACCESS,FLEX_DIRECT",
+  "numItineraries": 3,
+  "otherThanPreferredRoutesPenalty": 900,
+  "showIntermediateStops": true,
+  "time": "21:53",
+  "toPlace": "Municipal Wharf St, Santa Cruz, CA, 95060, USA::36.961843106786766,-122.02402657342725",
+}
+`;
+
 exports[`query getRoutingParams should create routing params for intermediate places query 1`] = `
 Object {
   "arriveBy": false,
@@ -124,6 +191,39 @@ Object {
 }
 `;
 
+exports[`query getRoutingParams should create routing params for standard flex query 1`] = `
+Object {
+  "arriveBy": false,
+  "date": "2020-08-24",
+  "fromPlace": "Steamer Lane, Santa Cruz, CA, 95060, USA::36.95471026341096,-122.0248185852425",
+  "ignoreRealtimeUpdates": false,
+  "maxWalkDistance": 1207,
+  "mode": "WALK,TRANSIT,FLEX_EGRESS,FLEX_ACCESS,FLEX_DIRECT",
+  "numItineraries": 3,
+  "optimize": "QUICK",
+  "otherThanPreferredRoutesPenalty": 900,
+  "showIntermediateStops": true,
+  "time": "21:53",
+  "toPlace": "Municipal Wharf St, Santa Cruz, CA, 95060, USA::36.961843106786766,-122.02402657342725",
+  "walkSpeed": 1.34,
+}
+`;
+
+exports[`query getRoutingParams should create routing params for standard flex query 2`] = `
+Object {
+  "arriveBy": false,
+  "date": "2020-08-24",
+  "fromPlace": "Steamer Lane, Santa Cruz, CA, 95060, USA::36.95471026341096,-122.0248185852425",
+  "ignoreRealtimeUpdates": false,
+  "mode": "FLEX_EGRESS,FLEX_ACCESS,FLEX_DIRECT",
+  "numItineraries": 3,
+  "otherThanPreferredRoutesPenalty": 900,
+  "showIntermediateStops": true,
+  "time": "21:53",
+  "toPlace": "Municipal Wharf St, Santa Cruz, CA, 95060, USA::36.961843106786766,-122.02402657342725",
+}
+`;
+
 exports[`query getRoutingParams should create routing params for transit query 1`] = `
 Object {
   "arriveBy": false,
diff --git a/packages/core-utils/src/__tests__/query-params.js b/packages/core-utils/src/__tests__/query-params.js
index 1ad5d7b93..3be578a84 100644
--- a/packages/core-utils/src/__tests__/query-params.js
+++ b/packages/core-utils/src/__tests__/query-params.js
@@ -1,3 +1,4 @@
+import { reduceOtpFlexModes } from "../query";
 import queryParams, { getCustomQueryParams } from "../query-params";
 
 const customWalkDistanceOptions = [
@@ -38,3 +39,55 @@ describe("query-params", () => {
     });
   });
 });
+
+describe("flex-reducer", () => {
+  it("should not touch a query that doesn't include flex modes", () => {
+    expect(reduceOtpFlexModes(["WALK", "TRANSIT", "BIKE"])).toStrictEqual([
+      "WALK",
+      "TRANSIT",
+      "BIKE"
+    ]);
+  });
+  it("should modify a query that includes some flex modes", () => {
+    expect(
+      reduceOtpFlexModes(["WALK", "TRANSIT", "BIKE", "FLEX_DIRECT"])
+    ).toStrictEqual(["WALK", "TRANSIT", "BIKE", "FLEX"]);
+  });
+  it("should modify a query that includes all flex modes", () => {
+    expect(
+      reduceOtpFlexModes([
+        "WALK",
+        "TRANSIT",
+        "BIKE",
+        "FLEX_DIRECT",
+        "FLEX_ACCESS",
+        "FLEX_EGRESS"
+      ])
+    ).toStrictEqual(["WALK", "TRANSIT", "BIKE", "FLEX"]);
+    expect(
+      reduceOtpFlexModes([
+        "FLEX_DIRECT",
+        "BIKE",
+        "FLEX_ACCESS",
+        "WALK",
+        "FLEX_EGRESS",
+        "TRANSIT"
+      ])
+    ).toStrictEqual(["FLEX", "BIKE", "WALK", "TRANSIT"]);
+  });
+  it("should modify a query that includes only flex modes", () => {
+    expect(
+      reduceOtpFlexModes(["FLEX_DIRECT", "FLEX_ACCESS", "FLEX_EGRESS"])
+    ).toStrictEqual(["FLEX"]);
+  });
+  it("should modify a query that includes duplicate flex modes", () => {
+    expect(
+      reduceOtpFlexModes([
+        "FLEX_DIRECT",
+        "FLEX_DIRECT",
+        "FLEX_ACCESS",
+        "FLEX_EGRESS"
+      ])
+    ).toStrictEqual(["FLEX"]);
+  });
+});
diff --git a/packages/core-utils/src/__tests__/query.js b/packages/core-utils/src/__tests__/query.js
index 0dbaf6c05..ebc217257 100644
--- a/packages/core-utils/src/__tests__/query.js
+++ b/packages/core-utils/src/__tests__/query.js
@@ -102,6 +102,58 @@ describe("query", () => {
         })
       ).toMatchSnapshot();
     });
+
+    it("should create routing params for standard flex query", () => {
+      expect(
+        getRoutingParams(fakeConfig, {
+          ...makeBaseTestQuery(),
+          mode: "WALK,TRANSIT,FLEX"
+        })
+      ).toMatchSnapshot();
+    });
+
+    it("should create repaired routing params for broken flex query", () => {
+      expect(
+        getRoutingParams(fakeConfig, {
+          ...makeBaseTestQuery(),
+          mode: "WALK,FLEX_DIRECT,TRANSIT,FLEX"
+        })
+      ).toMatchSnapshot();
+    });
+
+    it("should create routing params for flex-only query", () => {
+      expect(
+        getRoutingParams(fakeConfig, {
+          ...makeBaseTestQuery(),
+          mode: "FLEX"
+        })
+      ).toMatchSnapshot();
+    });
+
+    it("should create routing params for standard flex query", () => {
+      expect(
+        getRoutingParams(fakeConfig, {
+          ...makeBaseTestQuery(),
+          mode: "FLEX_EGRESS,FLEX_ACCESS,FLEX_DIRECT"
+        })
+      ).toMatchSnapshot();
+    });
+
+    it("should create repaired routing params for very broken flex query", () => {
+      expect(
+        getRoutingParams(fakeConfig, {
+          ...makeBaseTestQuery(),
+          mode: "FLEX_EGRESS,FLEX_ACCESS,FLEX_DIRECT,FLEX,WALK,BIKE"
+        })
+      ).toMatchSnapshot();
+      expect(
+        getRoutingParams(fakeConfig, {
+          ...makeBaseTestQuery(),
+          mode:
+            "FLEX_EGRESS,FLEX,FLEX_EGRESS,FLEX_ACCESS,FLEX_DIRECT,FLEX,WALK,BIKE,WALK,TRANSIT,BUS"
+        })
+      ).toMatchSnapshot();
+    });
   });
 
   describe("isNotDefaultQuery", () => {
diff --git a/packages/core-utils/src/query.js b/packages/core-utils/src/query.js
index 1f1d8432d..9fe6e41dc 100644
--- a/packages/core-utils/src/query.js
+++ b/packages/core-utils/src/query.js
@@ -182,6 +182,28 @@ export function reduceOtpFlexModes(modes) {
   }, []);
 }
 
+/**
+ * Helper method to process a mode string, replacing all instances of FLEX
+ * with the full set of FLEX modes used by otp-2
+ * @param {*} mode a mode String, not an array
+ * @returns a mode String, not an array (with flex modes expanded)
+ */
+export function expandOtpFlexMode(mode) {
+  const modes = reduceOtpFlexModes(mode.split(","));
+  return modes
+    .map(m => {
+      // If both the expanded and shrunk modes are included, remove the exapnded one
+      if (m === "FLEX_EGRESS" || m === "FLEX_ACCESS" || m === "FLEX_DIRECT") {
+        if (mode.includes("FLEX")) return "";
+      }
+      if (m === "FLEX") {
+        return "FLEX_EGRESS,FLEX_ACCESS,FLEX_DIRECT";
+      }
+      return m;
+    })
+    .join(",");
+}
+
 /**
  * Determines whether the specified query differs from the default query, i.e.,
  * whether the user has modified any trip options (including mode) from their
@@ -466,8 +488,8 @@ export function getRoutingParams(config, currentQuery, ignoreRealtimeUpdates) {
   // Replace FLEX placeholder with OTP flex modes
   if (params.mode) {
     // Ensure query is in reduced format to avoid replacing twice
-    const mode = reduceOtpFlexModes(params.mode.split(",")).join(",");
-    params.mode = mode.replace("FLEX", "FLEX_EGRESS,FLEX_ACCESS,FLEX_DIRECT");
+    const reducedMode = reduceOtpFlexModes(params.mode.split(",")).join(",");
+    params.mode = expandOtpFlexMode(reducedMode);
   }
 
   return params;