diff --git a/fuzzers/030-iob/generate.py b/fuzzers/030-iob/generate.py
index 87d0e013..2976a4f1 100644
--- a/fuzzers/030-iob/generate.py
+++ b/fuzzers/030-iob/generate.py
@@ -5,6 +5,7 @@ from prjxray import segmaker
 from prjxray import verilog
 import os
 import json
+import csv
 
 
 def bitfilter(frame, word):
@@ -20,20 +21,6 @@ def mk_drive_opt(iostandard, drive):
     return '{}.DRIVE.I{}'.format(iostandard, drive)
 
 
-def skip_broken_tiles(d):
-    """ Skip tiles that appear to have bits always set.
-
-    This is likely caused by a defect?
-
-    """
-    if os.getenv('XRAY_DATABASE') == 'artix7' and d['tile'] == 'LIOB33_X0Y43':
-        return True
-    if os.getenv('XRAY_DATABASE') == 'zynq7' and d['tile'] == 'RIOB33_X31Y43':
-        return True
-
-    return False
-
-
 def drives_for_iostandard(iostandard):
     if iostandard in ['LVTTL', 'LVCMOS18']:
         drives = [4, 8, 12, 16, 24]
@@ -71,6 +58,14 @@ def main():
     for iobank in iobanks:
         iobank_iostandards[iobank] = set()
 
+    # Load a list of PUDC_B pin function tiles. They are configured differently
+    # by the vendor tools so need to be skipped
+    pudc_tiles = set()
+    with open(os.path.join(os.getenv('FUZDIR'), 'build',
+                           'pudc_sites.csv')) as f:
+        for l in csv.DictReader(f):
+            pudc_tiles.add(l["tile"])
+
     print("Loading tags")
     segmk = Segmaker("design.bits")
     '''
@@ -90,7 +85,7 @@ def main():
         for d in design['tiles']:
             site = d['site']
 
-            if skip_broken_tiles(d):
+            if d['tile'] in pudc_tiles:
                 continue
 
             if site in diff_pairs:
diff --git a/fuzzers/030-iob/write_io_banks.tcl b/fuzzers/030-iob/write_io_banks.tcl
index 8ed0427c..190271b3 100644
--- a/fuzzers/030-iob/write_io_banks.tcl
+++ b/fuzzers/030-iob/write_io_banks.tcl
@@ -17,3 +17,19 @@ foreach site_type { IOB33M IOB33S IDELAYCTRL} {
     }
 }
 close $fp
+
+set fp [open "pudc_sites.csv" "w"]
+puts $fp "tile,site"
+foreach tile [get_tiles *IOB33*] {
+    foreach site [get_sites -of_objects $tile] {
+        set site_type [get_property SITE_TYPE $site]
+
+        set pin [get_package_pins -of_objects $site]
+        set pin_func [get_property PIN_FUNC $pin]
+
+        if {[string first "PUDC_B" $pin_func] != -1} {
+            puts $fp "$tile,$site,$site_type"
+        }
+    }
+}
+close $fp