From 2a3f80a82cc673036167d5371edc5abc169923a4 Mon Sep 17 00:00:00 2001
From: Ben Winslow <rain@bluecherry.net>
Date: Sun, 17 Aug 2025 22:09:42 -0400
Subject: [PATCH] [senseair] Discard 0 ppm readings with "Out Of Range" bit
 set. (#10275)

---
 esphome/components/senseair/senseair.cpp | 10 +++++++---
 esphome/components/senseair/senseair.h   | 11 +++++++++++
 2 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/esphome/components/senseair/senseair.cpp b/esphome/components/senseair/senseair.cpp
index e58ee157f7..84520d407d 100644
--- a/esphome/components/senseair/senseair.cpp
+++ b/esphome/components/senseair/senseair.cpp
@@ -53,10 +53,14 @@ void SenseAirComponent::update() {
 
   this->status_clear_warning();
   const uint8_t length = response[2];
-  const uint16_t status = (uint16_t(response[3]) << 8) | response[4];
-  const int16_t ppm = int16_t((response[length + 1] << 8) | response[length + 2]);
+  const uint16_t status = encode_uint16(response[3], response[4]);
+  const uint16_t ppm = encode_uint16(response[length + 1], response[length + 2]);
 
-  ESP_LOGD(TAG, "SenseAir Received CO₂=%dppm Status=0x%02X", ppm, status);
+  ESP_LOGD(TAG, "SenseAir Received CO₂=%uppm Status=0x%02X", ppm, status);
+  if (ppm == 0 && (status & SenseAirStatus::OUT_OF_RANGE_ERROR) != 0) {
+    ESP_LOGD(TAG, "Discarding 0 ppm reading with out-of-range status.");
+    return;
+  }
   if (this->co2_sensor_ != nullptr)
     this->co2_sensor_->publish_state(ppm);
 }
diff --git a/esphome/components/senseair/senseair.h b/esphome/components/senseair/senseair.h
index 9f939d5b07..5b66860f1a 100644
--- a/esphome/components/senseair/senseair.h
+++ b/esphome/components/senseair/senseair.h
@@ -8,6 +8,17 @@
 namespace esphome {
 namespace senseair {
 
+enum SenseAirStatus : uint8_t {
+  FATAL_ERROR = 1 << 0,
+  OFFSET_ERROR = 1 << 1,
+  ALGORITHM_ERROR = 1 << 2,
+  OUTPUT_ERROR = 1 << 3,
+  SELF_DIAGNOSTIC_ERROR = 1 << 4,
+  OUT_OF_RANGE_ERROR = 1 << 5,
+  MEMORY_ERROR = 1 << 6,
+  RESERVED = 1 << 7
+};
+
 class SenseAirComponent : public PollingComponent, public uart::UARTDevice {
  public:
   void set_co2_sensor(sensor::Sensor *co2_sensor) { co2_sensor_ = co2_sensor; }