diff --git a/tools/power-utils/updater.cpp b/tools/power-utils/updater.cpp
index deab95f..e26d1b0 100644
--- a/tools/power-utils/updater.cpp
+++ b/tools/power-utils/updater.cpp
@@ -17,6 +17,7 @@
 
 #include "updater.hpp"
 
+#include "pmbus.hpp"
 #include "types.hpp"
 #include "utility.hpp"
 
@@ -146,16 +147,85 @@
 
 bool Updater::isReadyToUpdate()
 {
+    using namespace phosphor::pmbus;
+
     // Pre-condition for updating PSU:
     // * Host is powered off
-    // * All other PSUs are having AC input
-    // * All other PSUs are having standby output
-    if (util::isPoweredOn(bus))
+    // * At least one other PSU is present
+    // * All other PSUs that are present are having AC input and DC standby
+    //   output
+
+    if (util::isPoweredOn(bus, true))
     {
+        log<level::WARNING>("Unable to update PSU when host is on");
         return false;
     }
-    // TODO
-    return true;
+
+    bool hasOtherPresent = false;
+    auto paths = util::getPSUInventoryPaths(bus);
+    for (const auto& p : paths)
+    {
+        if (p == psuInventoryPath)
+        {
+            // Skip check for itself
+            continue;
+        }
+
+        // Check PSU present
+        bool present = false;
+        try
+        {
+            auto service = util::getService(p, INVENTORY_IFACE, bus);
+            util::getProperty(INVENTORY_IFACE, PRESENT_PROP, psuInventoryPath,
+                              service, bus, present);
+        }
+        catch (const std::exception& e)
+        {
+            log<level::ERR>("Failed to get present property",
+                            entry("PSU=%s", p.c_str()));
+        }
+        if (!present)
+        {
+            log<level::WARNING>("PSU not present", entry("PSU=%s", p.c_str()));
+            continue;
+        }
+        hasOtherPresent = true;
+
+        // Typically the driver is still bound here, so it is possible to
+        // directly read the debugfs to get the status.
+        try
+        {
+            auto devPath = internal::getDevicePath(p);
+            PMBus pmbus(devPath);
+            uint16_t statusWord = pmbus.read(STATUS_WORD, Type::Debug);
+            auto status0Vout = pmbus.insertPageNum(STATUS_VOUT, 0);
+            uint8_t voutStatus = pmbus.read(status0Vout, Type::Debug);
+            if ((statusWord & status_word::VOUT_FAULT) ||
+                (statusWord & status_word::INPUT_FAULT_WARN) ||
+                (statusWord & status_word::VIN_UV_FAULT) ||
+                // For ibm-cffps PSUs, the MFR (0x80)'s OV (bit 2) and VAUX
+                // (bit 6) fault map to OV_FAULT, and UV (bit 3) fault maps to
+                // UV_FAULT in vout status.
+                (voutStatus & status_vout::UV_FAULT) ||
+                (voutStatus & status_vout::OV_FAULT))
+            {
+                log<level::WARNING>(
+                    "Unable to update PSU when other PSU has input/ouput fault",
+                    entry("PSU=%s", p.c_str()),
+                    entry("STATUS_WORD=0x%04x", statusWord),
+                    entry("VOUT_BYTE=0x%02x", voutStatus));
+                return false;
+            }
+        }
+        catch (const std::exception& ex)
+        {
+            // If error occurs on accessing the debugfs, it means something went
+            // wrong, e.g. PSU is not present, and it's not ready to update.
+            log<level::ERR>(ex.what());
+            return false;
+        }
+    }
+    return hasOtherPresent;
 }
 
 int Updater::doUpdate()