diff --git a/include/param_prj.h b/include/param_prj.h
index d35551a..646a4ff 100644
--- a/include/param_prj.h
+++ b/include/param_prj.h
@@ -129,7 +129,7 @@
 // SKUDAK customization suffix: bump on every Skudak-side change so the OpenInverter
 // web UI shows a distinct version (e.g. "4=1.20.R-S4") and we can visually confirm
 // the right firmware is flashed. Match the stm32-sine -S<N> convention.
-#define VERSTR STRINGIFY(4=VER-S5)
+#define VERSTR STRINGIFY(4=VER-S6)
 
 /***** enums ******/
 
diff --git a/src/main.cpp b/src/main.cpp
index 790efe8..7d490d6 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -114,10 +114,22 @@ static void MapChargerMessages()
    float dummyGain;
    bool dummyrx;
 
-   //check sample value, if it is mapped assume valid CAN map
-   if (canMap->FindMap(Param::hwaclim, dummyId, dummyOfs, dummyLen, dummyGain, dummyAdd, dummyrx)) return;
+   // SKUDAK: tmpobcmax is the canary for the -S5+ CAN-map schema. If it's
+   // already mapped, the persistent flash map was built by a firmware that
+   // included the full current set of mappings (including the OBC temp
+   // aggregate and all c1*/c2*/c3* receives) — return early so user
+   // customizations are preserved.
+   //
+   // If tmpobcmax is NOT mapped, the saved map is from an older firmware
+   // that didn't know about it. We must wipe and rebuild from current
+   // chargercan.cpp — without this the OpenInverter single-shot MapMessages()
+   // pattern silently leaves newer params un-mapped on every subsequent
+   // boot, even after flashing fresh firmware (the original guard keyed off
+   // hwaclim, which has existed since the very first version — so it always
+   // short-circuited on upgrade and the new entries were dead code).
+   if (canMap->FindMap(Param::tmpobcmax, dummyId, dummyOfs, dummyLen, dummyGain, dummyAdd, dummyrx)) return;
 
-   //canMap->Clear();
+   canMap->Clear();
 
    ChargerCAN::MapMessages(canMap);