diff --git a/ArduPlane/AP_Arming.cpp b/ArduPlane/AP_Arming.cpp
index 5ff6f88b42..3f7cd17f7a 100644
--- a/ArduPlane/AP_Arming.cpp
+++ b/ArduPlane/AP_Arming.cpp
@@ -167,6 +167,10 @@ bool AP_Arming_Plane::quadplane_checks(bool display_failure)
         check_failed(ARMING_CHECK_PARAMETERS, display_failure, "Bad parameter: %s", failure_msg);
         ret = false;
     }
+    if (!plane.quadplane.motors->check_mot_pwm_params()) {
+        check_failed(ARMING_CHECK_PARAMETERS, display_failure, "Check Q_M_PWM_MIN/MAX");
+        ret = false;
+    }
 
     if ((plane.quadplane.options & QuadPlane::OPTION_ONLY_ARM_IN_QMODE_OR_AUTO) != 0) {
         if (!plane.control_mode->is_vtol_mode() && (plane.control_mode != &plane.mode_auto) && (plane.control_mode != &plane.mode_guided)) {
diff --git a/ArduPlane/quadplane.cpp b/ArduPlane/quadplane.cpp
index 64bcb16df9..9ed1623712 100644
--- a/ArduPlane/quadplane.cpp
+++ b/ArduPlane/quadplane.cpp
@@ -534,14 +534,16 @@ const AP_Param::ConversionInfo q_conversion_table[] = {
     { Parameters::k_param_quadplane, 1467,  AP_PARAM_FLOAT,  "Q_TILT_FIX_ANGLE" },
     { Parameters::k_param_quadplane, 1531,  AP_PARAM_FLOAT,  "Q_TILT_FIX_GAIN" },
 
-    { Parameters::k_param_quadplane, 22,  AP_PARAM_INT16, "Q_M_PWM_MIN" },
-    { Parameters::k_param_quadplane, 23,  AP_PARAM_INT16, "Q_M_PWM_MAX" },
-
     // PARAMETER_CONVERSION - Added: Jan-2022
     { Parameters::k_param_quadplane, 33,  AP_PARAM_FLOAT, "Q_WVANE_GAIN" },     // Moved from quadplane to weathervane library
     { Parameters::k_param_quadplane, 34,  AP_PARAM_FLOAT, "Q_WVANE_ANG_MIN" },  // Q_WVANE_MINROLL moved from quadplane to weathervane library
 };
 
+// PARAMETER_CONVERSION - Added: Oct-2021
+const AP_Param::ConversionInfo mot_pwm_conversion_table[] = {
+    { Parameters::k_param_quadplane, 22,  AP_PARAM_INT16, "Q_M_PWM_MIN" },
+    { Parameters::k_param_quadplane, 23,  AP_PARAM_INT16, "Q_M_PWM_MAX" },
+};
 
 QuadPlane::QuadPlane(AP_AHRS &_ahrs) :
     ahrs(_ahrs)
@@ -716,6 +718,12 @@ bool QuadPlane::setup(void)
     motors->set_update_rate(rc_speed);
     attitude_control->parameter_sanity_check();
 
+    // Try to convert mot PWM params, if still invalid force conversion
+    AP_Param::convert_old_parameters(&mot_pwm_conversion_table[0], ARRAY_SIZE(mot_pwm_conversion_table));
+    if (!motors->check_mot_pwm_params()) {
+        AP_Param::convert_old_parameters(&mot_pwm_conversion_table[0], ARRAY_SIZE(mot_pwm_conversion_table), AP_Param::CONVERT_FLAG_FORCE);
+    }
+
     // setup the trim of any motors used by AP_Motors so I/O board
     // failsafe will disable motors
     uint32_t mask = plane.quadplane.motors->get_motor_mask();