diff --git a/oscar/SleepLib/loader_plugins/prs1_loader.cpp b/oscar/SleepLib/loader_plugins/prs1_loader.cpp
index f1bae2a8..4e39d9a5 100644
--- a/oscar/SleepLib/loader_plugins/prs1_loader.cpp
+++ b/oscar/SleepLib/loader_plugins/prs1_loader.cpp
@@ -4141,13 +4141,14 @@ bool PRS1DataChunk::ParseSettingsF3V6(const unsigned char* data, int size)
                 // TODO: We probably need additional enums for these modes, the below are just a rough guess mapping for now.
                 switch (data[pos]) {
                 case 1: cpapmode = MODE_BILEVEL_FIXED; break;  // "S" mode
-                case 2: cpapmode = MODE_ASV; break;  // "S/T" mode; pressure seems variable?
+                case 2: cpapmode = MODE_BILEVEL_FIXED; break;  // "S/T" mode; pressure seems variable?
                 case 4: cpapmode = MODE_AVAPS; break;  // "PC" mode? Usually "PC - AVAPS", see setting 1 below
+                // TODO: fixed vs. variable PS seems to be independent from ventilator mode, for example
+                // S/T can be fixed (single IPAP pressure) or variable (IPAP min/max).
                 default:
                     UNEXPECTED_VALUE(data[pos], "known device mode");
                     break;
                 }
-                this->AddEvent(new PRS1ParsedSettingEvent(PRS1_SETTING_CPAP_MODE, (int) cpapmode));
                 break;
             case 1: // ???
                 // How do these interact with the mode above?
@@ -4173,6 +4174,9 @@ bool PRS1DataChunk::ParseSettingsF3V6(const unsigned char* data, int size)
                 break;
             case 8:  // Min IPAP
                 CHECK_VALUE(fixed_ipap, 0);
+                if (cpapmode == MODE_BILEVEL_FIXED) {
+                    cpapmode = MODE_BILEVEL_AUTO_VARIABLE_PS;  // TODO: this isn't quite right, it's actually fixed EPAP with variable PS
+                }
                 min_ipap = data[pos];
                 this->AddEvent(new PRS1PressureSettingEvent(PRS1_SETTING_IPAP_MIN, min_ipap, GAIN));
                 // TODO: We need to revisit whether PS should be shown as a setting.
@@ -4193,7 +4197,7 @@ bool PRS1DataChunk::ParseSettingsF3V6(const unsigned char* data, int size)
                 // TODO: add a setting for this
                 break;
             case 0x1e:  // Backup rate (S/T and AVAPS)
-                CHECK_VALUES(cpapmode, MODE_ASV, MODE_AVAPS);
+                //CHECK_VALUES(cpapmode, MODE_BILEVEL_FIXED, MODE_AVAPS);  // TODO: this should be testing for S/T rather than bilevel
                 // TODO: Does mode breath rate off mean this is essentially bilevel? The pressure graphs are confusing.
                 CHECK_VALUES(data[pos], 0, 2);  // 0 = Breath Rate off (S), 2 = fixed BPM (1 = auto on F5V3 setting 0x14)
                 //CHECK_VALUE(data[pos+1], 10);  // BPM for mode 2
@@ -4245,6 +4249,8 @@ bool PRS1DataChunk::ParseSettingsF3V6(const unsigned char* data, int size)
 
         pos += len;
     } while (ok && pos + 2 <= size);
+    
+    this->AddEvent(new PRS1ParsedSettingEvent(PRS1_SETTING_CPAP_MODE, (int) cpapmode));
 
     return ok;
 }