diff --git a/PWGCF/EbyEFluctuations/Tasks/FactorialMomentsTask.cxx b/PWGCF/EbyEFluctuations/Tasks/FactorialMomentsTask.cxx
index f01ce200c9b..f28fe6d641e 100644
--- a/PWGCF/EbyEFluctuations/Tasks/FactorialMomentsTask.cxx
+++ b/PWGCF/EbyEFluctuations/Tasks/FactorialMomentsTask.cxx
@@ -170,19 +170,18 @@ struct FactorialMomentsTask {
   const double dcaxyMaxTrackPar0 = 0.0105;
   const double dcaxyMaxTrackPar1 = 0.035;
   const double dcaxyMaxTrackPar2 = 1.1;
-  const double dcazMaxTrack = 2.0;
   static const int nBins = 52;
   double kMinCharge = 1e-6;
   static const int nfqOrder = 6;
   int countSamples = 0;
   int testc1 = 0, testc2 = 0, testc3 = 0;
-  std::array<int, nBins> binningM;
+  std::array<int, nBins> binningM{};
   std::array<int, 5> countTracks{0, 0, 0, 0, 0};
-  std::array<std::array<std::array<double, nBins>, 5>, 6> fqEvent;
-  std::array<std::array<std::array<double, nBins>, 5>, 6> fqEventSampled;
-  std::array<std::array<double, nBins>, 5> binConEvent;
-  std::array<std::array<std::array<double, nBins>, 5>, 6> binConEventSampled;
-  std::array<std::array<std::array<double, nBins>, 5>, 6> errorFq = {{{{{0, 0, 0, 0, 0}}}}};
+  std::array<std::array<std::array<double, nBins>, 5>, 6> fqEvent{};
+  std::array<std::array<std::array<double, nBins>, 5>, 6> fqEventSampled{};
+  std::array<std::array<double, nBins>, 5> binConEvent{};
+  std::array<std::array<std::array<double, nBins>, 5>, 6> binConEventSampled{};
+  std::array<std::array<std::array<int, nBins>, 5>, nfqOrder> nSubsamples{};
   std::vector<std::shared_ptr<TH2>> mHistArrReset;
   std::vector<std::shared_ptr<TH1>> mHistArrQA;
   std::vector<std::shared_ptr<TH3>> mHistArrEff;
@@ -191,9 +190,7 @@ struct FactorialMomentsTask {
   std::vector<std::shared_ptr<TH1>> mFqBinFinalSampled;
   std::vector<std::shared_ptr<TH1>> mBinConFinalSampled;
   std::vector<std::shared_ptr<TH1>> mFqError;
-  // max number of bins restricted to 5
-  static constexpr std::array<std::string_view, 5>
-    mbinNames{"bin1/", "bin2/", "bin3/", "bin4/", "bin5/"};
+
   void init(o2::framework::InitContext&)
   {
     // NOTE: check to make number of pt and the vector consistent
@@ -307,23 +304,28 @@ struct FactorialMomentsTask {
         }
         binConEvent[iPt][iM] = binContent / (std::pow(binningM[iM], 2));
         for (int iq = 0; iq < nfqOrder; ++iq) {
-          if (sumfqBin[iq] > 0) {
-            fqEvent[iq][iPt][iM] = sumfqBin[iq] / (std::pow(binningM[iM], 2));
-            fqEventSampled[iq][iPt][iM] += fqEvent[iq][iPt][iM];
-          }
+          // Always accumulate raw fq numerator and binCon unconditionally so
+          // both sums run over exactly the same set of events.
+          fqEvent[iq][iPt][iM] = sumfqBin[iq] / (std::pow(binningM[iM], 2));
+          fqEventSampled[iq][iPt][iM] += fqEvent[iq][iPt][iM];
           binConEventSampled[iq][iPt][iM] += binConEvent[iPt][iM];
           mFqBinFinal[iPt * 6 + iq]->Fill(iM, fqEvent[iq][iPt][iM]);
           mBinConFinal[iPt * 6 + iq]->Fill(iM, binConEvent[iPt][iM]);
           if (compSample) {
-            mBinConFinalSampled[iPt * 6 + iq]->Fill(iM, binConEventSampled[iq][iPt][iM] / samplesize);
+            const double avM = binConEventSampled[iq][iPt][iM] / samplesize;
+            mBinConFinalSampled[iPt * 6 + iq]->Fill(iM, avM);
+            const double den = std::pow(avM, iq + 2);
+            const double fqM = ((fqEventSampled[iq][iPt][iM]) / samplesize);
 
-            double tmp = (fqEventSampled[iq][iPt][iM] / (samplesize)) / (std::pow(binConEventSampled[iq][iPt][iM] / (samplesize), (iq + 2)));
+            const double tmp = (den > 0.) ? fqM / den : 0.;
             mFqBinFinalSampled[iPt * 6 + iq]->Fill(iM, tmp);
-            tmpFqErr[iq][iPt][iM]->Fill(tmp);
-            errorFq[iq][iPt][iM] += std::pow(fqEventSampled[iq][iPt][iM] / (samplesize), 2);
-            mFqError[iPt * 6 + iq]->SetBinContent(iM + 1, 0);
-            mFqError[iPt * 6 + iq]->Fill(iM, tmpFqErr[iq][iPt][iM]->GetStdDev());
 
+            tmpFqErr[iq][iPt][iM]->Fill(tmp);
+            ++nSubsamples[iq][iPt][iM];
+            const double stdErr = (nSubsamples[iq][iPt][iM] > 1)
+                                    ? tmpFqErr[iq][iPt][iM]->GetStdDev() / std::sqrt(static_cast<double>(nSubsamples[iq][iPt][iM]))
+                                    : 0.;
+            mFqError[iPt * 6 + iq]->SetBinContent(iM + 1, stdErr);
             fqEventSampled[iq][iPt][iM] = 0;
             binConEventSampled[iq][iPt][iM] = 0;
           }