diff --git a/libraries/AP_NavEKF3/AP_NavEKF3_core.cpp b/libraries/AP_NavEKF3/AP_NavEKF3_core.cpp
index 933fc37248..83e4783078 100644
--- a/libraries/AP_NavEKF3/AP_NavEKF3_core.cpp
+++ b/libraries/AP_NavEKF3/AP_NavEKF3_core.cpp
@@ -1135,7 +1135,7 @@ void NavEKF3_core::CovariancePrediction(Vector3F *rotVarVecPtr)
         ftype _gyrNoise = constrain_ftype(frontend->_gyrNoise, 0.0f, 1.0f);
         daxVar = dayVar = dazVar = sq(dt*_gyrNoise);
     }
-    ftype _accNoise = constrain_ftype(frontend->_accNoise, 0.0f, 10.0f);
+    ftype _accNoise = badIMUdata ? BAD_IMU_DATA_ACC_P_NSE : constrain_ftype(frontend->_accNoise, 0.0f, 10.0f);
     dvxVar = dvyVar = dvzVar = sq(dt*_accNoise);
 
     if (!inhibitDelVelBiasStates) {
diff --git a/libraries/AP_NavEKF3/AP_NavEKF3_core.h b/libraries/AP_NavEKF3/AP_NavEKF3_core.h
index 2a89f1a5ab..1337083683 100644
--- a/libraries/AP_NavEKF3/AP_NavEKF3_core.h
+++ b/libraries/AP_NavEKF3/AP_NavEKF3_core.h
@@ -96,6 +96,8 @@
 #define EK3_POSXY_STATE_LIMIT 1.0e6
 #endif
 
+#define BAD_IMU_DATA_ACC_P_NSE 5.0f
+
 class NavEKF3_core : public NavEKF_core_common
 {
 public: