diff --git a/rocketpy/mathutils/function.py b/rocketpy/mathutils/function.py
index 7981bbbfa..2ae7e077f 100644
--- a/rocketpy/mathutils/function.py
+++ b/rocketpy/mathutils/function.py
@@ -98,7 +98,6 @@ def __init__(
         (II) Fields in CSV files may be enclosed in double quotes. If fields are
         not quoted, double quotes should not appear inside them.
         """
-        # Set input and output
         if inputs is None:
             inputs = ["Scalar"]
         if outputs is None:
@@ -3018,7 +3017,7 @@ def _check_user_input(
         if isinstance(inputs, str):
             inputs = [inputs]
 
-        elif len(outputs) > 1:
+        if len(outputs) > 1:
             raise ValueError(
                 "Output must either be a string or have dimension 1, "
                 + f"it currently has dimension ({len(outputs)})."
@@ -3035,8 +3034,16 @@ def _check_user_input(
                 try:
                     source = np.loadtxt(source, delimiter=",", dtype=float)
                 except ValueError:
-                    # Skip header
-                    source = np.loadtxt(source, delimiter=",", dtype=float, skiprows=1)
+                    with open(source, "r") as file:
+                        header, *data = file.read().splitlines()
+                    header = [
+                        label.strip("'").strip('"') for label in header.split(",")
+                    ]
+                    if inputs == ["Scalar"]:
+                        inputs = header[:-1]
+                    if outputs == ["Scalar"]:
+                        outputs = [header[-1]]
+                    source = np.loadtxt(data, delimiter=",", dtype=float)
                 except Exception as e:
                     raise ValueError(
                         "The source file is not a valid csv or txt file."
@@ -3054,7 +3061,7 @@ def _check_user_input(
 
             ## single dimension
             if source_dim == 2:
-                # possible interpolation values: llinear, polynomial, akima and spline
+                # possible interpolation values: linear, polynomial, akima and spline
                 if interpolation is None:
                     interpolation = "spline"
                 elif interpolation.lower() not in [
@@ -3105,7 +3112,7 @@ def _check_user_input(
             in_out_dim = len(inputs) + len(outputs)
             if source_dim != in_out_dim:
                 raise ValueError(
-                    "Source dimension ({source_dim}) does not match input "
+                    f"Source dimension ({source_dim}) does not match input "
                     + f"and output dimension ({in_out_dim})."
                 )
         return inputs, outputs, interpolation, extrapolation
diff --git a/tests/test_function.py b/tests/test_function.py
index 6896b01af..2ce94f691 100644
--- a/tests/test_function.py
+++ b/tests/test_function.py
@@ -49,7 +49,7 @@ def test_func_from_csv_with_header(csv_file):
     line. It tests cases where the fields are separated by quotes and without
     quotes."""
     f = Function(csv_file)
-    assert f.__repr__() == "'Function from R1 to R1 : (Scalar) → (Scalar)'"
+    assert f.__repr__() == "'Function from R1 to R1 : (time) → (value)'"
     assert np.isclose(f(0), 100)
     assert np.isclose(f(0) + f(1), 300), "Error summing the values of the function"