diff --git a/libraries/AP_ESC_Telem/AP_ESC_Telem.cpp b/libraries/AP_ESC_Telem/AP_ESC_Telem.cpp
index 9945d16ce45784..0ebc163c2d27ed 100644
--- a/libraries/AP_ESC_Telem/AP_ESC_Telem.cpp
+++ b/libraries/AP_ESC_Telem/AP_ESC_Telem.cpp
@@ -107,7 +107,7 @@ uint32_t AP_ESC_Telem::get_active_esc_mask() const {
             // have never seen telem from this ESC
             continue;
         }
-        if (now - _telem_data[i].last_update_ms >= ESC_TELEM_DATA_TIMEOUT_MS
+        if (_telem_data[i].stale(now)
             && !rpm_data_within_timeout(_rpm_data[i], now_us, ESC_RPM_DATA_TIMEOUT_US)) {
             continue;
         }
@@ -211,7 +211,7 @@ bool AP_ESC_Telem::get_raw_rpm(uint8_t esc_index, float& rpm) const
 bool AP_ESC_Telem::get_temperature(uint8_t esc_index, int16_t& temp) const
 {
     if (esc_index >= ESC_TELEM_MAX_ESCS
-        || AP_HAL::millis() - _telem_data[esc_index].last_update_ms > ESC_TELEM_DATA_TIMEOUT_MS
+        || _telem_data[esc_index].stale()
         || !(_telem_data[esc_index].types & (AP_ESC_Telem_Backend::TelemetryType::TEMPERATURE | AP_ESC_Telem_Backend::TelemetryType::TEMPERATURE_EXTERNAL))) {
         return false;
     }
@@ -223,7 +223,7 @@ bool AP_ESC_Telem::get_temperature(uint8_t esc_index, int16_t& temp) const
 bool AP_ESC_Telem::get_motor_temperature(uint8_t esc_index, int16_t& temp) const
 {
     if (esc_index >= ESC_TELEM_MAX_ESCS
-        || AP_HAL::millis() - _telem_data[esc_index].last_update_ms > ESC_TELEM_DATA_TIMEOUT_MS
+        || _telem_data[esc_index].stale()
         || !(_telem_data[esc_index].types & (AP_ESC_Telem_Backend::TelemetryType::MOTOR_TEMPERATURE | AP_ESC_Telem_Backend::TelemetryType::MOTOR_TEMPERATURE_EXTERNAL))) {
         return false;
     }
@@ -251,7 +251,7 @@ bool AP_ESC_Telem::get_highest_motor_temperature(int16_t& temp) const
 bool AP_ESC_Telem::get_current(uint8_t esc_index, float& amps) const
 {
     if (esc_index >= ESC_TELEM_MAX_ESCS
-        || AP_HAL::millis() - _telem_data[esc_index].last_update_ms > ESC_TELEM_DATA_TIMEOUT_MS
+        || _telem_data[esc_index].stale()
         || !(_telem_data[esc_index].types & AP_ESC_Telem_Backend::TelemetryType::CURRENT)) {
         return false;
     }
@@ -263,7 +263,7 @@ bool AP_ESC_Telem::get_current(uint8_t esc_index, float& amps) const
 bool AP_ESC_Telem::get_voltage(uint8_t esc_index, float& volts) const
 {
     if (esc_index >= ESC_TELEM_MAX_ESCS
-        || AP_HAL::millis() - _telem_data[esc_index].last_update_ms > ESC_TELEM_DATA_TIMEOUT_MS
+        || _telem_data[esc_index].stale()
         || !(_telem_data[esc_index].types & AP_ESC_Telem_Backend::TelemetryType::VOLTAGE)) {
         return false;
     }
@@ -275,7 +275,7 @@ bool AP_ESC_Telem::get_voltage(uint8_t esc_index, float& volts) const
 bool AP_ESC_Telem::get_consumption_mah(uint8_t esc_index, float& consumption_mah) const
 {
     if (esc_index >= ESC_TELEM_MAX_ESCS
-        || AP_HAL::millis() - _telem_data[esc_index].last_update_ms > ESC_TELEM_DATA_TIMEOUT_MS
+        || _telem_data[esc_index].stale()
         || !(_telem_data[esc_index].types & AP_ESC_Telem_Backend::TelemetryType::CONSUMPTION)) {
         return false;
     }
@@ -287,7 +287,7 @@ bool AP_ESC_Telem::get_consumption_mah(uint8_t esc_index, float& consumption_mah
 bool AP_ESC_Telem::get_usage_seconds(uint8_t esc_index, uint32_t& usage_s) const
 {
     if (esc_index >= ESC_TELEM_MAX_ESCS
-        || AP_HAL::millis() - _telem_data[esc_index].last_update_ms > ESC_TELEM_DATA_TIMEOUT_MS
+        || _telem_data[esc_index].stale()
         || !(_telem_data[esc_index].types & AP_ESC_Telem_Backend::TelemetryType::USAGE)) {
         return false;
     }
@@ -324,7 +324,7 @@ void AP_ESC_Telem::send_esc_telemetry_mavlink(uint8_t mav_chan)
         for (uint8_t j=0; j<4; j++) {
             const uint8_t esc_id = (i * 4 + j) + esc_offset;
             if (esc_id < ESC_TELEM_MAX_ESCS &&
-                (now - _telem_data[esc_id].last_update_ms <= ESC_TELEM_DATA_TIMEOUT_MS ||
+                (!_telem_data[esc_id].stale(now) ||
                  rpm_data_within_timeout(_rpm_data[esc_id], now_us, ESC_RPM_DATA_TIMEOUT_US))) {
                 all_stale = false;
                 break;
diff --git a/libraries/AP_ESC_Telem/AP_ESC_Telem.h b/libraries/AP_ESC_Telem/AP_ESC_Telem.h
index 503ef43299dfce..a63ebf2ca2bdaa 100644
--- a/libraries/AP_ESC_Telem/AP_ESC_Telem.h
+++ b/libraries/AP_ESC_Telem/AP_ESC_Telem.h
@@ -78,6 +78,11 @@ class AP_ESC_Telem {
     // ESC_TELEM_DATA_TIMEOUT_MS
     uint32_t get_active_esc_mask() const;
 
+    /*
+      check if a last_update_ms is in range. If now_ms is 0 then use current time
+     */
+    bool check_last_update_ms(uint8_t esc_index, uint32_t now_ms) const;
+
     // return the last time telemetry data was received in ms for the given ESC or 0 if never
     uint32_t get_last_telem_data_ms(uint8_t esc_index) const {
         if (esc_index >= ESC_TELEM_MAX_ESCS) {return 0;}
diff --git a/libraries/AP_ESC_Telem/AP_ESC_Telem_Backend.cpp b/libraries/AP_ESC_Telem/AP_ESC_Telem_Backend.cpp
index b104c835628210..0048571452f230 100644
--- a/libraries/AP_ESC_Telem/AP_ESC_Telem_Backend.cpp
+++ b/libraries/AP_ESC_Telem/AP_ESC_Telem_Backend.cpp
@@ -40,4 +40,15 @@ void AP_ESC_Telem_Backend::update_telem_data(const uint8_t esc_index, const Tele
     _frontend->update_telem_data(esc_index, new_data, data_present_mask);
 }
 
-#endif
\ No newline at end of file
+/*
+  return true if the data is stale
+ */
+bool AP_ESC_Telem_Backend::TelemetryData::stale(uint32_t now_ms) const volatile
+{
+    if (now_ms == 0) {
+        now_ms = AP_HAL::millis();
+    }
+    return last_update_ms == 0 || now_ms - last_update_ms > ESC_TELEM_DATA_TIMEOUT_MS;
+}
+
+#endif
diff --git a/libraries/AP_ESC_Telem/AP_ESC_Telem_Backend.h b/libraries/AP_ESC_Telem/AP_ESC_Telem_Backend.h
index e40c09b64a3c9e..b6d6725a55fa15 100644
--- a/libraries/AP_ESC_Telem/AP_ESC_Telem_Backend.h
+++ b/libraries/AP_ESC_Telem/AP_ESC_Telem_Backend.h
@@ -19,6 +19,9 @@ class AP_ESC_Telem_Backend {
         uint32_t last_update_ms;    // last update time in milliseconds, determines whether active
         uint16_t types;             // telemetry types present
         uint16_t count;             // number of times updated
+
+        // return true if the data is stale
+        bool stale(uint32_t now_ms=0) const volatile;
     };
 
     struct RpmData {