Белорусский Audi Клуб

18613/P2181/008577 - Performance Malfunction in Cooling System

Possible Symptoms
Malfunction Indicator Light (MIL) ON
Reduced Heater Output - Cold toes
Incorrect Temperature Gauge Readings
Increased Emissions

Possible Causes
Faulty Coolant Sensor
Faulty Coolant Thermostat
Faulty Wiring, Connections
Note: This fault code sets when engine coolant temperature mapping is lower and out of expected range based on operating conditions of the engine.
For example: Engine warms up, thermostat opens and stays open, coolant temperature drops below normal operating range. The ECM knows the coolant temperature should stay within 80.0...110.0 °C typically after warm up. Thus a drop in coolant temperature below normal operating temperature is not possible without a Malfunction in Cooling System.

Possible Solutions
Check G62 - Engine Coolant Temperature Sender
Inspect wiring for G62 (Coolant Migration, damage, corrosion, etc)
Check (if applicable) G83 - Radiator Outlet, Coolant Temperature Sender
Inspect wiring for G83 (Coolant Migration, damage, corrosion, etc)
Check Coolant Thermostat
Use Graph function in VCDS, Measuring Value Blocks - MVB
Start Engine cold, graph Coolant Temperature Sender (G62) Typically MVB Group-001
Hold RPM around 1,500rpm and watch coolant temp increase in Graph until thermostat opens, indicated by a slight drop in coolant temp
If coolant temp drops below minimum operating temperature (80°C) or never reaches operating temperature, (verified by external thermometer) suspect failed thermostat
Vehicles with both G62-Engine Outlet, Coolant Temperature Sensor and G83-Radiator Outlet, Coolant Temperature Sensor
Use Measuring Value Block group MVB-130 instead on MVB-001
G62 should increase in Temperature before G83 increase when engine coolant is cold
G83 will increase when the thermostat opens and after G62 reaches operating temperature (80°C)
If G62 and G83 both increase while engine warms up, suspect failed thermostat

Special Notes
Check the stored Freeze Frame data with this fault code. Freeze Frame information will be found in the fault code description (if the module supports it) or in Generic OBD-II if the vehicle complies with those regulations.
Freeze Frame data stored at -40*C is generally an indication of a faulty ECT or wiring.
Freeze Frame data stored at +140*C is generally an indication of a faulty ECT or wiring.
Freeze Frame data stored with in the 68*C ~ 80*C range is an indication that the vehicle was close to, but not within, the cooling systems normal operation range. The Thermostat itself or Cooling system components may be at fault.