Code P2185 2005 VW Jetta 2.5 5cyl

The fan or fans that cool the engine are not turned on until the engine coolant reaches about 225-230F, so they may not run for a long time, if it is not overheating why are you concerned.

The fans are run by rad temperature, not engine temp on a VW.Somewhere on the rad you should see a wire harness plugged into it.That is a thermo-switch which turns the fans on and off based on coolant temp in the rad. My car is a lot older than yours but this switch is virtually hidden on the bottom driver's side of the rad. It has 3 wires going into it.There could also be another sensor attached to the engine block or head to monitor engine compartment temps after engine shut off. This will turn the fans on or off as well based on air temp in the engine compartment.

Make sure coolant level is as it should be. If level is low look for evidence of leak(s). Top off fluid if necessary. The engine coolant temperature sensor is a very common issue with these vehicles and may be the cause of your issues if no leaks are found. Also a faulty thermostat cans cause the sensors to read voltage high but most likely a sensor issue. The sensor is a potentiometer (variable resistor). The computer sends 5v through one of the wires this voltage goes through a resistor which will vary the voltage based on temperature sensed by the engine coolant temperature sensor. The sensor has a negative temparature coefficient meaning the resistance will go down when temperature is high and up when temperature is low. The less resistance the more of the 5 v gets back to the computer. The PCM detects this high voltage and set the check engine light on warning you of an issue. Whe this sensor goes bad it is usually accompanied by temperature gauge fluctuation or erratic operation and the cooling fans run long or all the time even though the vehicle is cold. Hope this helps.

If your radiator fans are not running at all than I would check over the wires your disconnected when rpolacing the temp sensor. Make sure they are fully connected. That would be the first thing I would check.

Good Luck

I WOULD CHECK BOTH RADIATOR HOSES TO MAKE SURE THEY ARE HOT. THERMOSTAT COULD BE STICKING SLIGHTLY CLOSED.CHECK COOLANT LEVEL MAKE SURE COOLANT NOT LOW.IF COOLING NOT BOILING OUT OF THE EXPANSION TANK. I WOULD HAVE CAR HOOKED UP TO A DIAGNOTIC SCANNER AND CHECK COOLANT TEMPERATURE SEE IF TEMP. OVER 230 DEGREES IF SO RADIATOR COOLING FANS NOT WORKING.COOLANT THERMO SWITCH BAD BOTH FANS SHOULD BE RUNNING AT LOW SPEED.IF ALL LOOKS GOOD YOU COULD HAVE FAULTY LOW COOLANT SENSOR IN EXPANSION TANK.MAKE SURE COOLANT IS IN THE EXPANSION TANK BECAUSE COOLANT LEVEL COULD BE LOW.ADD COOLANT IN THE EXPANSION TANK UNTIL YOU AT MAX LEVEL LINE ON THE EXPANSION TANK.DONT OVER FILL THE EXPANSION KEEP ADDING COOLANT UNTIL COOLANT LEVEL STAYS AT THE MAX LEVEL LINE ON THE EXPANSION TANK.

Since you say you changed the thermostat, and that wasn't it then possibly the cooling fan is not functioning properly. Or bad water pump,inaccurate temperature gauge, radiator core blocked or restricted. These are just the most common reasons. Good Luck and I hope this helps a little

Both of these codes indicate trouble with the signal from the coolant temperature sensor.

So either the sensor is bad. The thermostat is not working properly and the coolant temperature is truly way out. The wiring to the sensor is short or open. The computer is bad and it is manifesting itself through this fault.

Does the car warm up properly? If it runs hot, or takes forever to warm up, this indicates a problem with the thermostat.

If the car runs at the proper temperature the next thing to look at is the coolant temp sensor and wiring. Some resistance values for VWs are here:
http://forums.vwvortex.com/zerothread?id=4267675

You might also be interested in this recall if your car is below 100k miles:
http://forums.vwvortex.com/zerothread?id=3694323

Get another boyfriend! "Just kidding"! ok, this is what I mean about "leaving it to the experts". #1 Make sure there is enough coolant, Check for leaks. Install a coolant pressure tester and check for leaks. Fix whats leaking. #2 Make sure coolant fans are coming on, and specifically at 220 degrees. If not, check fuses. Jump the coolant fan to make sure it comes on. if it does, then you may have a bad relay, make sure relay is commanded on. At this point , you may need a wire schematic for the coolant fans and related parts.

disconnect the cooling fan temperature sensor on the engione that turns on the fan, if the fans runs the switch/sensor is defective.

Check for a switch at lower part of rad. Should see a wire harness & plug on a sensor at bottom of rad. This sensor/switch also operates fan on/off according to coolant temperature. You may need to disconnect battery to get at it safely.