diff --git a/firmware/controllers/algo/engine.cpp b/firmware/controllers/algo/engine.cpp
index 2b65c6dd13..f8009e4b48 100644
--- a/firmware/controllers/algo/engine.cpp
+++ b/firmware/controllers/algo/engine.cpp
@@ -108,7 +108,10 @@ void Engine::periodicSlowCallback(DECLARE_ENGINE_PARAMETER_SIGNATURE) {
 	checkShutdown();
 
 #if EFI_FSIO || defined(__DOXYGEN__)
+// todo: enable this for unit tests
+#if ! EFI_UNIT_TEST
 	runFsio(PASS_ENGINE_PARAMETER_SIGNATURE);
+#endif
 #endif /* EFI_PROD_CODE && EFI_FSIO */
 
 	cylinderCleanupControl(PASS_ENGINE_PARAMETER_SIGNATURE);
diff --git a/firmware/controllers/algo/engine2.cpp b/firmware/controllers/algo/engine2.cpp
index 77c133c0be..d01182afc0 100644
--- a/firmware/controllers/algo/engine2.cpp
+++ b/firmware/controllers/algo/engine2.cpp
@@ -121,7 +121,7 @@ void EngineState::updateSlowSensors(DECLARE_ENGINE_PARAMETER_SIGNATURE) {
 
 void EngineState::periodicFastCallback(DECLARE_ENGINE_PARAMETER_SIGNATURE) {
 	if (!engine->slowCallBackWasInvoked) {
-//		warning(CUSTOM_ERR_6696, "Slow not invoked yet");
+		warning(CUSTOM_ERR_6696, "Slow not invoked yet");
 	}
 	efitick_t nowNt = getTimeNowNt();
 	if (ENGINE(rpmCalculator).isCranking(PASS_ENGINE_PARAMETER_SIGNATURE)) {
diff --git a/unit_tests/engine_test_helper.cpp b/unit_tests/engine_test_helper.cpp
index f46f054a1e..4f7bb18cd2 100644
--- a/unit_tests/engine_test_helper.cpp
+++ b/unit_tests/engine_test_helper.cpp
@@ -67,7 +67,8 @@ EngineTestHelper::EngineTestHelper(engine_type_e engineType) : engine (&persiste
 	testIatValue = 4.03646;
 
 	// this is needed to have valid CLT and IAT.
-	engine->updateSlowSensors(PASS_ENGINE_PARAMETER_SIGNATURE);
+//todo: reuse 	initPeriodicEvents(PASS_ENGINE_PARAMETER_SIGNATURE) method
+	engine->periodicSlowCallback(PASS_ENGINE_PARAMETER_SIGNATURE);
 
 	engine->initializeTriggerShape(NULL PASS_ENGINE_PARAMETER_SUFFIX);
 	engine->triggerCentral.addEventListener(rpmShaftPositionCallback, "rpm reporter", engine);