diff --git a/firmware/lambda_conversion.cpp b/firmware/lambda_conversion.cpp
index e433008..b5bad49 100644
--- a/firmware/lambda_conversion.cpp
+++ b/firmware/lambda_conversion.cpp
@@ -3,6 +3,18 @@
 
 static float GetPhi(float pumpCurrent)
 {
+    // Maximum lambda ~2
+    if (pumpCurrent > 1.11f)
+    {
+        return 0.5f;
+    }
+
+    // Minimum lambda ~0.65
+    if (pumpCurrent < -1.87f)
+    {
+        return 1 / 0.65f;
+    }
+
     // This estimation is accurate within 0.5% from 0.8 to 1.0, and 0.01% from 1 to 1.2 lambda when compared to the lookup table in the Bosch datasheet
     // This error is less than half of the claimed accuracy of the sensor itself
     float gain = pumpCurrent < 0 ? -0.28299f : -0.44817f;