diff --git a/rust/src/tank.rs b/rust/src/tank.rs
index f0a1de8..152fc29 100644
--- a/rust/src/tank.rs
+++ b/rust/src/tank.rs
@@ -86,7 +86,10 @@ impl TankState {
     pub fn warn_level(&self, config: &TankConfig) -> Result<bool, TankError> {
         match self {
             TankState::TankSensorDisabled => Err(TankError::SensorDisabled),
-            TankState::TankSensorError(err) => Err(err.clone()),
+            TankState::TankSensorError(err) => match err {
+                TankError::SensorValueError { value, min, max } => Ok(value < min),
+                _ => Err(err.clone()),
+            },
             TankState::TankSensorPresent(raw_value_mv) => {
                 let tank_fill_percent = raw_voltage_to_tank_fill_percent(*raw_value_mv, config)?;
                 if tank_fill_percent < config.tank_warn_percent.into() {