diff --git a/pybamm/solvers/base_solver.py b/pybamm/solvers/base_solver.py
index 81e74f89c9..434e1b91e7 100644
--- a/pybamm/solvers/base_solver.py
+++ b/pybamm/solvers/base_solver.py
@@ -1407,12 +1407,11 @@ def map_func_over_inputs(name, f, vars_for_processing, ninputs):
         dictionary of variables for processing
     ninputs: int
         number of inputs to map over
-    add_v: bool
-        whether to add a vector v to the inputs
     """
     if f is None:
         return None
 
+    is_event = "event" in name
     add_v = name.endswith("_action")
     matrix_output = name.endswith("_jac") or name.endswith("_jacp")
 
@@ -1448,6 +1447,10 @@ def map_func_over_inputs(name, f, vars_for_processing, ninputs):
         splits = [i * nstates for i in range(ninputs + 1)]
         split = casadi.horzsplit(mapped_f, splits)
         stack = casadi.diagcat(*split)
+    elif is_event:
+        # Events need to return a scalar, so we combine the vector output
+        # of the mapped function into a scalar output by calculating a smooth max of the vector output.
+        stack = casadi.logsumexp(casadi.transpose(mapped_f), 1e-4)
     else:
         # for vector outputs we need to stack them vertically in a single column vector
         splits = [i for i in range(ninputs + 1)]
diff --git a/pybamm/solvers/solution.py b/pybamm/solvers/solution.py
index fe1bbc6e49..8f5dc23c79 100644
--- a/pybamm/solvers/solution.py
+++ b/pybamm/solvers/solution.py
@@ -167,17 +167,18 @@ def split(self, rhs_len, alg_len, inputs_list):
                 ]
                 for p in range(ninputs)
             ]
-            y_events = [
-                casadi.vertcat(
-                    self.y_event[(p * rhs_len) : (p * rhs_len + rhs_len)],
-                    self.y_event[
-                        (p * alg_len + ninputs * rhs_len) : (
-                            p * alg_len + ninputs * rhs_len + alg_len
-                        )
-                    ],
-                )
-                for p in range(ninputs)
-            ]
+            if self.y_event is not None:
+                y_events = [
+                    casadi.vertcat(
+                        self.y_event[(p * rhs_len) : (p * rhs_len + rhs_len)],
+                        self.y_event[
+                            (p * alg_len + ninputs * rhs_len) : (
+                                p * alg_len + ninputs * rhs_len + alg_len
+                            )
+                        ],
+                    )
+                    for p in range(ninputs)
+                ]
         else:
             all_ys_split = [
                 [
@@ -195,19 +196,20 @@ def split(self, rhs_len, alg_len, inputs_list):
                 ]
                 for p in range(ninputs)
             ]
-            y_events = [
-                np.vstack(
-                    [
-                        self.y_event[(p * rhs_len) : (p * rhs_len + rhs_len)],
-                        self.y_event[
-                            (p * alg_len + ninputs * rhs_len) : (
-                                p * alg_len + ninputs * rhs_len + alg_len
-                            )
-                        ],
-                    ]
-                )
-                for p in range(ninputs)
-            ]
+            if self.y_event is not None:
+                y_events = [
+                    np.vstack(
+                        [
+                            self.y_event[(p * rhs_len) : (p * rhs_len + rhs_len)],
+                            self.y_event[
+                                (p * alg_len + ninputs * rhs_len) : (
+                                    p * alg_len + ninputs * rhs_len + alg_len
+                                )
+                            ],
+                        ]
+                    )
+                    for p in range(ninputs)
+                ]
 
         ret = [
             type(self)(
diff --git a/tests/unit/test_solvers/test_casadi_solver.py b/tests/unit/test_solvers/test_casadi_solver.py
index 6a79d639f2..5ad24810b6 100644
--- a/tests/unit/test_solvers/test_casadi_solver.py
+++ b/tests/unit/test_solvers/test_casadi_solver.py
@@ -396,6 +396,7 @@ def test_model_solver_with_inputs(self):
         t_eval = np.linspace(0, 10, 100)
         solution = solver.solve(model, t_eval, inputs={"rate": 0.1})
         self.assertLess(len(solution.t), len(t_eval))
+        single_len = len(solution.t)
         np.testing.assert_allclose(
             solution.y.full()[0], np.exp(-0.1 * solution.t), rtol=1e-04
         )
@@ -407,6 +408,7 @@ def test_model_solver_with_inputs(self):
         self.assertEqual(len(solutions), 2)
         for solution, rate in zip(solutions, [0.1, 0.2]):
             self.assertLess(len(solution.t), len(t_eval))
+            self.assertEqual(len(solution.t), single_len)
             np.testing.assert_allclose(
                 solution.y.full()[0], np.exp(-rate * solution.t), rtol=1e-04
             )