diff --git a/selfdrive/car/gm/carcontroller.py b/selfdrive/car/gm/carcontroller.py
index c94f693c72..8f4d0f27ca 100644
--- a/selfdrive/car/gm/carcontroller.py
+++ b/selfdrive/car/gm/carcontroller.py
@@ -14,6 +14,7 @@ class CarController():
   def __init__(self, dbc_name, CP, VM):
     self.start_time = 0.
     self.apply_steer_last = 0
+    self.lka_steering_cmd_counter_last = -1
     self.lka_icon_status_last = (False, False)
     self.steer_rate_limited = False
 
@@ -31,8 +32,12 @@ class CarController():
     # Send CAN commands.
     can_sends = []
 
-    # STEER
-    if (frame % P.STEER_STEP) == 0:
+    # Steering (50Hz)
+    # Avoid GM EPS faults when transmitting messages too close together: skip this transmit if we just received the
+    # next Panda loopback confirmation in the current CS frame.
+    if CS.lka_steering_cmd_counter != self.lka_steering_cmd_counter_last:
+      self.lka_steering_cmd_counter_last = CS.lka_steering_cmd_counter
+    elif (frame % P.STEER_STEP) == 0:
       lkas_enabled = enabled and not (CS.out.steerWarning or CS.out.steerError) and CS.out.vEgo > P.MIN_STEER_SPEED
       if lkas_enabled:
         new_steer = int(round(actuators.steer * P.STEER_MAX))
@@ -42,7 +47,9 @@ class CarController():
         apply_steer = 0
 
       self.apply_steer_last = apply_steer
-      idx = (frame // P.STEER_STEP) % 4
+      # GM EPS faults on any gap in received message counters. To handle transient OP/Panda safety sync issues at the
+      # moment of disengaging, increment the counter based on the last message known to pass Panda safety checks.
+      idx = (CS.lka_steering_cmd_counter + 1) % 4
 
       can_sends.append(gmcan.create_steering_control(self.packer_pt, CanBus.POWERTRAIN, apply_steer, idx, lkas_enabled))
 
diff --git a/selfdrive/car/gm/carstate.py b/selfdrive/car/gm/carstate.py
index f16f5e542a..00f25c5fdb 100644
--- a/selfdrive/car/gm/carstate.py
+++ b/selfdrive/car/gm/carstate.py
@@ -13,8 +13,9 @@ class CarState(CarStateBase):
     super().__init__(CP)
     can_define = CANDefine(DBC[CP.carFingerprint]["pt"])
     self.shifter_values = can_define.dv["ECMPRDNL"]["PRNDL"]
+    self.lka_steering_cmd_counter = 0
 
-  def update(self, pt_cp):
+  def update(self, pt_cp, loopback_cp):
     ret = car.CarState.new_message()
 
     self.prev_cruise_buttons = self.cruise_buttons
@@ -42,6 +43,7 @@ class CarState(CarStateBase):
     ret.steeringTorque = pt_cp.vl["PSCMStatus"]["LKADriverAppldTrq"]
     ret.steeringTorqueEps = pt_cp.vl["PSCMStatus"]["LKATorqueDelivered"]
     ret.steeringPressed = abs(ret.steeringTorque) > STEER_THRESHOLD
+    self.lka_steering_cmd_counter = loopback_cp.vl["ASCMLKASteeringCmd"]["RollingCounter"]
 
     # 0 inactive, 1 active, 2 temporarily limited, 3 failed
     self.lkas_status = pt_cp.vl["PSCMStatus"]["LKATorqueDeliveredStatus"]
@@ -131,3 +133,15 @@ class CarState(CarStateBase):
       ]
 
     return CANParser(DBC[CP.carFingerprint]["pt"], signals, checks, CanBus.POWERTRAIN)
+
+  @staticmethod
+  def get_loopback_can_parser(CP):
+    signals = [
+      ("RollingCounter", "ASCMLKASteeringCmd", 0),
+    ]
+
+    checks = [
+      ("ASCMLKASteeringCmd", 50),
+    ]
+
+    return CANParser(DBC[CP.carFingerprint]["pt"], signals, checks, CanBus.LOOPBACK)
diff --git a/selfdrive/car/gm/interface.py b/selfdrive/car/gm/interface.py
index 4719a5db5a..e9b5a13e7a 100755
--- a/selfdrive/car/gm/interface.py
+++ b/selfdrive/car/gm/interface.py
@@ -144,10 +144,11 @@ class CarInterface(CarInterfaceBase):
   # returns a car.CarState
   def update(self, c, can_strings):
     self.cp.update_strings(can_strings)
+    self.cp_loopback.update_strings(can_strings)
 
-    ret = self.CS.update(self.cp)
+    ret = self.CS.update(self.cp, self.cp_loopback)
 
-    ret.canValid = self.cp.can_valid
+    ret.canValid = self.cp.can_valid and self.cp_loopback.can_valid
     ret.steeringRateLimited = self.CC.steer_rate_limited if self.CC is not None else False
 
     buttonEvents = []
diff --git a/selfdrive/car/gm/values.py b/selfdrive/car/gm/values.py
index 85be9334c0..d475b4bd67 100644
--- a/selfdrive/car/gm/values.py
+++ b/selfdrive/car/gm/values.py
@@ -68,6 +68,7 @@ class CanBus:
   OBSTACLE = 1
   CHASSIS = 2
   SW_GMLAN = 3
+  LOOPBACK = 128
 
 FINGERPRINTS = {
   # Astra BK MY17, ASCM unplugged
diff --git a/selfdrive/car/interfaces.py b/selfdrive/car/interfaces.py
index ada906367e..6e148b96a2 100644
--- a/selfdrive/car/interfaces.py
+++ b/selfdrive/car/interfaces.py
@@ -39,6 +39,7 @@ class CarInterfaceBase():
       self.cp = self.CS.get_can_parser(CP)
       self.cp_cam = self.CS.get_cam_can_parser(CP)
       self.cp_body = self.CS.get_body_can_parser(CP)
+      self.cp_loopback = self.CS.get_loopback_can_parser(CP)
 
     self.CC = None
     if CarController is not None:
@@ -254,3 +255,7 @@ class CarStateBase:
   @staticmethod
   def get_body_can_parser(CP):
     return None
+
+  @staticmethod
+  def get_loopback_can_parser(CP):
+    return None
diff --git a/selfdrive/test/process_replay/ref_commit b/selfdrive/test/process_replay/ref_commit
index 009b94c106..767b66c691 100644
--- a/selfdrive/test/process_replay/ref_commit
+++ b/selfdrive/test/process_replay/ref_commit
@@ -1 +1 @@
-58674945e8c265e2c1f53500fc9cab2ed9a815b0
\ No newline at end of file
+4ad66f0fea4c42e79ba347a73ff839e5369c0411
\ No newline at end of file