diff --git a/openmc/data/mf33_njoy.py b/openmc/data/mf33_njoy.py
index 6fcf4af5a0..0c687eeab2 100644
--- a/openmc/data/mf33_njoy.py
+++ b/openmc/data/mf33_njoy.py
@@ -46,6 +46,20 @@ def _read_mat_from_endf(endf_path: Path) -> int:
         raise ValueError(f"Could not infer MAT from ENDF file: {endf_path}")
     return first_nonzero
 
+def _endf_has_mf33(endf_path: Path, mat: int) -> bool:
+    """Return True if the ENDF tape contains any MF=33 section for this MAT."""
+    with endf_path.open("r", errors="ignore") as f:
+        for line in f:
+            if len(line) < 75:
+                continue
+            try:
+                m  = int(line[66:70])
+                mf = int(line[70:72])
+            except ValueError:
+                continue
+            if m == mat and mf == 33:
+                return True
+    return False
 
 def _validate_energy_grid_ev(ek: Sequence[float]) -> List[float]:
     ek = [float(x) for x in ek]
@@ -130,7 +144,7 @@ def _errorr_mf33_input(
     mat: int,
     temperature: float,
     ek: Sequence[float],
-    iwt: int = 2,
+    iwt: int = 6,
     spectrum: Optional[Sequence[float]] = None,
     relative: bool = True,
     irespr: int = 1,
@@ -288,12 +302,12 @@ def generate_errorr_mf33(
     temperature: float = 293.6,
     # processing chain
     err: float = NJOY_tolerance,
-    minimal_processing: bool = True,
+    minimal_processing: bool = False,
     thermr: bool = False,
-    unresr: bool = False,
-    purr: bool = False,
+    unresr: bool = True,
+    purr: bool = True,
     # ERRORR options
-    iwt: int = 2,
+    iwt: int = 6,
     spectrum: Optional[Sequence[float]] = None,
     relative: bool = True,
     irespr: int = 1,
@@ -350,6 +364,12 @@ def generate_errorr_mf33(
     if mat is None:
         mat = _read_mat_from_endf(endf_path)
 
+    if not _endf_has_mf33(endf_path, mat):
+        raise ValueError(
+            f"ENDF file {endf_path.name} (MAT={mat}) contains no MF=33 "
+            f"covariance data; nothing for ERRORR to process."
+        )
+
     if minimal_processing:
         thermr = unresr = purr = False
 
diff --git a/openmc/data/xs_covariance_njoy.py b/openmc/data/xs_covariance_njoy.py
index 55078a272a..60f9d4243f 100644
--- a/openmc/data/xs_covariance_njoy.py
+++ b/openmc/data/xs_covariance_njoy.py
@@ -562,16 +562,16 @@ class NeutronXSCovariances:
                 else:
                     n_cross += 1
                     cross_pairs.append((int(mt_key), int(mt1_key)))
-        log.debug(
+        log.info(
             "ERRORR tape33 parsed: %d MT section(s), "
             "%d self-covariance block(s), %d cross-covariance block(s)",
             len(reactions), n_self, n_cross,
         )
         if cross_pairs:
             for mt_a, mt1_a in cross_pairs:
-                log.debug("  cross-covariance: MT %d <-> MT %d", mt_a, mt1_a)
+                log.info("  cross-covariance: MT %d <-> MT %d", mt_a, mt1_a)
         else:
-            log.debug(
+            log.info(
                 "  No explicit cross-covariance blocks in ERRORR output.  "
                 "Cross-reaction correlations (if any) are handled implicitly "
                 "via NC-type derivation relations in the evaluation."
@@ -589,7 +589,7 @@ class NeutronXSCovariances:
                     )
                 elif qa.status == "warn":
                     n_warnings += 1
-                    log.debug(
+                    log.info(
                         "Stage-1 MF=33 warning for MT %s -> MT1 %s: %s",
                         mt, mt1, "; ".join(qa.messages)
                     )
@@ -602,7 +602,7 @@ class NeutronXSCovariances:
                 fcache[mt_key] = {}
                 for mt1, M in sec.get("COVS", {}).items():
                     if int(mt_key) != int(mt1):
-                        log.debug(
+                        log.info(
                             "  MT %s -> MT1 %s: cross-block (%d x %d), "
                             "stored raw (no factorization)",
                             mt_key, mt1,
@@ -616,7 +616,7 @@ class NeutronXSCovariances:
                     fcache[mt_key][mt1] = result
                     if result.method == "eigen_qr":
                         n_eigen_qr += 1
-                    log.debug(
+                    log.info(
                         "  MT %s -> MT1 %s: method=%-9s  rank=%d/%d  ",
                         mt_key, mt1,
                         result.method,