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DTC Decoded: P2181

VW technician

Diagnostic code:



All 1996 and up



Code detection:

This is a generic powertrain code that relates to all makes and models from 1996 to present. This code is triggered if the engine temperature registers too high or too low.

Symptoms of this code:

  • The temperature gauge is running too hot or too cold
  • The radiator will overflow or steam if the engine is running too hot
  • If it is running too cold, the heater will not work, and you will get poor gas mileage

What causes this code?

There are any number of causes for this code, so it must be properly diagnosed

What the techs say:

Since overheating causes immediate and expensive damage to the engine, it is best to stop immediately and shut off the engine if you see it overheating. Expanding steam can blow out head gaskets and cause hoses to break. An engine with extensive overheating can be destroyed when the pistons seize up. If your vehicle overheats, do not open the radiator. Built up hot water can exceed 280 degrees, and the release of pressure by removing the cap will cause this hot water to shoot out the top of the radiator.

In order to make a proper diagnosis of this code, you will need access to these tools:

  • Service manual for your vehicle
  • Scan tool for code clearing
  • Scan tool to determine the temperature
  • A voltmeter
  • A set of alligator jumper wires
  • Pressure tester for the coolant system

If you find the temperature is running too cool, then you may need to replace the thermostat.

If you find the temperature is running too hot, then here is a list of things that can cause an overheating engine:

  • Check to see if you have a blown head gasket
  • Check the coolant level on your cold engine. Use a pressure tester to see if there are any leaks. Look around the radiator, the intake, the heater core, the block and all the hoses.
  • If you only overheat when you are stopped, then it is a malfunctioning radiator fan.
  • Check for the proper tension on your serpentine belt. If a belt tensioner is defective, it will allow the belt to slip. Sometimes there may be a water pump leak, and this will show up as leaks from the bottom of the belt cover.
  • Check the coolant level sensor. It is on the side of the radiator. You may need to check your service manual for more information.
  • Use the code scanner and plug it into the OBD port. Turn the key on and look for more codes. If there is a coolant temperature sensor code, it will cause the malfunction of the radiator fans.
  • If you can see your water pump, see if the pulley has a wobble in it. This may indicate the water pump bushing is worn.
  • Your engine fan is another place you may find a wobble. There can be a leak in the fan clutch. Your fan should give you some resistance when you try to rotate it by hand. If the fan is running slowly while the engine is running, it may have a bad fan clutch.
  • While the engine is cold, take the radiator cap off and start the engine. Allow it to warm up while monitoring the engine temperature by using the scan tool. When the temperature gets to 190 degrees, you should see coolant moving in the radiator cores. If you do not see a flow of coolant, shut the car off and replace the cap. You have a defective thermostat.
  • If you do see radiator fluid flowing, put the cap back on and let the car warm up to 205 degrees. The electric fans should come on, but if they do not shut the motor off. Take a look at the engine fan fuse and relays to determine if there is a blown fuse. They are on the driver’s side in the fenderwell. You will see them listed on the cover.
  • You can check the fan by disconnecting the wiring. Place your jumper from the ground terminal to a ground and power terminal on the battery. If the fan fails, you will need to replace it. If it works, then check for loose wiring or connections at the fuse block and coolant temperature sensor. You may also see wiring that has burn marks or damaged connector pins.