diff --git a/openpilot/common/params_keys.h b/openpilot/common/params_keys.h
index 29a0a2117..6e4ada136 100644
--- a/openpilot/common/params_keys.h
+++ b/openpilot/common/params_keys.h
@@ -138,6 +138,7 @@ inline static std::unordered_map<std::string, ParamKeyAttributes> keys = {
     {"UptimeOnroad", {PERSISTENT, FLOAT, "0.0"}},
     {"ChestnutActive", {CLEAR_ON_MANAGER_START | CLEAR_ON_OFFROAD_TRANSITION | CLEAR_ON_IGNITION_ON, BOOL}},
     {"ChestnutLoading", {CLEAR_ON_MANAGER_START | CLEAR_ON_OFFROAD_TRANSITION | CLEAR_ON_IGNITION_ON, BOOL}},
+    {"ChestnutModelError", {CLEAR_ON_MANAGER_START | CLEAR_ON_OFFROAD_TRANSITION | CLEAR_ON_IGNITION_ON, BOOL}},
     {"Version", {PERSISTENT, STRING}},
 
     // --- sunnypilot params --- //
diff --git a/openpilot/selfdrive/modeld/helpers.py b/openpilot/selfdrive/modeld/helpers.py
index d08105005..23eb6cbd2 100644
--- a/openpilot/selfdrive/modeld/helpers.py
+++ b/openpilot/selfdrive/modeld/helpers.py
@@ -11,6 +11,8 @@ from openpilot.common.hardware.usb import CHESTNUT_USB_PRODUCT, USB_DEVICES_PATH
 
 MODELS_DIR = Path(__file__).resolve().parent / 'models'
 TG_INPUT_DEVICES_PATH = MODELS_DIR / 'tg_input_devices.json'
+CHESTNUT_POWERED_VOLTAGE = 5000
+CHESTNUT_PCIE_READY = 0x78
 
 
 def get_tg_input_devices(process_name: str, chestnut: bool):
@@ -58,3 +60,7 @@ def chestnut_present() -> bool:
 
 def chestnut_compiled() -> bool:
   return Path(get_manifest_path(modeld_pkl_path(chestnut=True))).is_file()
+
+
+def chestnut_ready(state) -> bool:
+  return state.supplyVoltage >= CHESTNUT_POWERED_VOLTAGE and not state.supplyFault and state.pcieLtssm == CHESTNUT_PCIE_READY