diff --git a/libraries/AP_HAL/Device.cpp b/libraries/AP_HAL/Device.cpp
index ad4a3ed4e2..740562eab6 100644
--- a/libraries/AP_HAL/Device.cpp
+++ b/libraries/AP_HAL/Device.cpp
@@ -103,12 +103,13 @@ bool AP_HAL::Device::check_next_register(void)
 
     if (_bank_select) {
         if (!_bank_select(reg.bank)) {
-        // Cannot set bank
+            // Cannot set bank
 #if 0
-        printf("Device 0x%x set bank 0x%02x\n",
-               (unsigned)get_bus_id(),
-               (unsigned)reg.bank);
+            printf("Device 0x%x set bank 0x%02x\n",
+                   (unsigned)get_bus_id(),
+                   (unsigned)reg.bank);
 #endif
+            _checked.last_reg_fail = reg;
             return false;
         }
     }
@@ -123,8 +124,22 @@ bool AP_HAL::Device::check_next_register(void)
                (unsigned)reg.regnum, (unsigned)v, (unsigned)reg.value);
 #endif
         write_register(reg.regnum, reg.value);
+        _checked.last_reg_fail = reg;
+        _checked.last_reg_fail.value = v;
         return false;
     }
     _checked.next = (_checked.next+1) % _checked.n_set;
     return true;
 }
+
+/*
+  check one register value, returning information on the failure
+ */
+bool AP_HAL::Device::check_next_register(struct checkreg &fail)
+{
+    if (check_next_register()) {
+        return true;
+    }
+    fail = _checked.last_reg_fail;
+    return false;
+}
diff --git a/libraries/AP_HAL/Device.h b/libraries/AP_HAL/Device.h
index 5402bd3d5c..ac67f70c00 100644
--- a/libraries/AP_HAL/Device.h
+++ b/libraries/AP_HAL/Device.h
@@ -201,6 +201,20 @@ public:
      */
     bool check_next_register(void);
 
+    // checked registers
+    struct checkreg {
+        uint8_t bank;
+        uint8_t regnum;
+        uint8_t value;
+    };
+    
+    /**
+     * check next register value for correctness, with return of
+     * failure value. Return false if value is incorrect or register
+     * checking has not been setup
+     */
+    bool check_next_register(struct checkreg &fail);
+    
     /**
      * Wrapper function over #transfer() to read a sequence of bytes from
      * device. No value is written, differently from the #read_registers()
@@ -390,18 +404,13 @@ protected:
 private:
     BankSelectCb _bank_select;
 
-    // checked registers
-    struct checkreg {
-        uint8_t bank;
-        uint8_t regnum;
-        uint8_t value;
-    };
     struct {
         uint8_t n_allocated;
         uint8_t n_set;
         uint8_t next;
         uint8_t frequency;
         uint8_t counter;
+        struct checkreg last_reg_fail;
         struct checkreg *regs;
     } _checked;
 };