diff --git a/MC/config/PWGHF/ini/GeneratorHF_HFe_ccbar_and_bbar_gap5_Mode2_pp_ref.ini b/MC/config/PWGHF/ini/GeneratorHF_HFe_ccbar_and_bbar_gap5_Mode2_pp_ref.ini
new file mode 100644
index 000000000..202b484b5
--- /dev/null
+++ b/MC/config/PWGHF/ini/GeneratorHF_HFe_ccbar_and_bbar_gap5_Mode2_pp_ref.ini
@@ -0,0 +1,9 @@
+#NEV_TEST> 20
+### The external generator derives from GeneratorPythia8.
+[GeneratorExternal]
+fileName=${O2DPG_MC_CONFIG_ROOT}/MC/config/PWGHF/external/generator/generator_pythia8_gaptriggered_hf.C
+funcName=GeneratorPythia8GapTriggeredCharmAndBeauty(5, -1.5, 1.5, -1.0, 1.0, {11})
+
+[GeneratorPythia8]
+config=${O2DPG_MC_CONFIG_ROOT}/MC/config/PWGHF/pythia8/generator/pythia8_HFe_Mode2_pp_ref.cfg
+includePartonEvent=true
diff --git a/MC/config/PWGHF/ini/tests/GeneratorHF_HFe_ccbar_and_bbar_gap5_Mode2_pp_ref.C b/MC/config/PWGHF/ini/tests/GeneratorHF_HFe_ccbar_and_bbar_gap5_Mode2_pp_ref.C
new file mode 100644
index 000000000..fb9df800e
--- /dev/null
+++ b/MC/config/PWGHF/ini/tests/GeneratorHF_HFe_ccbar_and_bbar_gap5_Mode2_pp_ref.C
@@ -0,0 +1,128 @@
+int External() {
+  std::string path{"o2sim_Kine.root"};
+
+  int checkPdgDecayElectron = 11;
+  int checkPdgQuarkOne = 4;
+  int checkPdgQuarkTwo = 5;
+  float ratioTrigger = 1. / 5; // one event triggered out of 5
+
+  TFile file(path.c_str(), "READ");
+  if (file.IsZombie()) {
+    std::cerr << "Cannot open ROOT file" << path << "\n";
+    return 1;
+  }
+
+  auto tree = (TTree *)file.Get("o2sim");
+  if (!tree) {
+    std::cerr << "Cannot find tree o2sim in file" << path << "\n";
+    return 1;
+  }
+
+  std::vector<o2::MCTrack> *tracks{};
+  tree->SetBranchAddress("MCTrack", &tracks);
+  o2::dataformats::MCEventHeader *eventHeader = nullptr;
+  tree->SetBranchAddress("MCEventHeader.", &eventHeader);
+
+  int nEventsMB{}, nEventsInjOne{}, nEventsInjTwo{};
+  int nQuarksOne{}, nQuarksTwo{};
+  int nElectrons{};
+  auto nEvents = tree->GetEntries();
+
+  for (int i = 0; i < nEvents; i++) {
+    tree->GetEntry(i);
+
+    // check subgenerator information
+    if (eventHeader->hasInfo(o2::mcgenid::GeneratorProperty::SUBGENERATORID)) {
+      bool isValid = false;
+      int subGeneratorId = eventHeader->getInfo<int>(
+          o2::mcgenid::GeneratorProperty::SUBGENERATORID, isValid);
+      if (subGeneratorId == 0) {
+        nEventsMB++;
+      } else if (subGeneratorId == checkPdgQuarkOne) {
+        nEventsInjOne++;
+      } else if (subGeneratorId == checkPdgQuarkTwo) {
+        nEventsInjTwo++;
+      }
+    } // if event header
+
+    int nelectronsev = 0;
+
+    for (auto &track : *tracks) {
+      auto pdg = track.GetPdgCode();
+      if (std::abs(pdg) == checkPdgQuarkOne) {
+        nQuarksOne++;
+        continue;
+      }
+      if (std::abs(pdg) == checkPdgQuarkTwo) {
+        nQuarksTwo++;
+        continue;
+      }
+
+      auto y = track.GetRapidity();
+      if (std::abs(pdg) == checkPdgDecayElectron) {
+        int igmother = track.getMotherTrackId();
+        auto gmTrack = (*tracks)[igmother];
+        int gmpdg = gmTrack.GetPdgCode();
+        if (int(std::abs(gmpdg) / 100.) == 4 ||
+            int(std::abs(gmpdg) / 1000.) == 4 ||
+            int(std::abs(gmpdg) / 100.) == 5 ||
+            int(std::abs(gmpdg) / 1000.) == 5) {
+          nElectrons++;
+          nelectronsev++;
+        } // gmpdg
+      } // pdgdecay
+    } // loop track
+    // std::cout << "#electrons per event: " << nelectronsev << "\n";
+  }
+
+  std::cout << "--------------------------------\n";
+  std::cout << "# Events: " << nEvents << "\n";
+  std::cout << "# MB events: " << nEventsMB << "\n";
+  std::cout << Form("# events injected with %d quark pair: ", checkPdgQuarkOne)
+            << nEventsInjOne << "\n";
+  std::cout << Form("# events injected with %d quark pair: ", checkPdgQuarkTwo)
+            << nEventsInjTwo << "\n";
+  std::cout << Form("# %d (anti)quarks: ", checkPdgQuarkOne) << nQuarksOne
+            << "\n";
+  std::cout << Form("# %d (anti)quarks: ", checkPdgQuarkTwo) << nQuarksTwo
+            << "\n";
+
+  if (nEventsMB < nEvents * (1 - ratioTrigger) * 0.95 ||
+      nEventsMB > nEvents * (1 - ratioTrigger) *
+                      1.05) { // we put some tolerance since the number of
+                              // generated events is small
+    std::cerr << "Number of generated MB events different than expected\n";
+    return 1;
+  }
+  if (nEventsInjOne < nEvents * ratioTrigger * 0.5 * 0.95 ||
+      nEventsInjOne > nEvents * ratioTrigger * 0.5 * 1.05) {
+    std::cerr << "Number of generated events injected with " << checkPdgQuarkOne
+              << " different than expected\n";
+    return 1;
+  }
+  if (nEventsInjTwo < nEvents * ratioTrigger * 0.5 * 0.95 ||
+      nEventsInjTwo > nEvents * ratioTrigger * 0.5 * 1.05) {
+    std::cerr << "Number of generated events injected with " << checkPdgQuarkTwo
+              << " different than expected\n";
+    return 1;
+  }
+  if (nQuarksOne <
+      nEvents *
+          ratioTrigger) { // we expect anyway more because the same quark is
+                          // repeated several time, after each gluon radiation
+    std::cerr << "Number of generated (anti)quarks " << checkPdgQuarkOne
+              << " lower than expected\n";
+    return 1;
+  }
+  if (nQuarksTwo <
+      nEvents *
+          ratioTrigger) { // we expect anyway more because the same quark is
+                          // repeated several time, after each gluon radiation
+    std::cerr << "Number of generated (anti)quarks " << checkPdgQuarkTwo
+              << " lower than expected\n";
+    return 1;
+  }
+  std::cout << "#electrons: " << nElectrons << "\n";
+
+  return 0;
+} // external