One of the most interesting Christmas's of all times. Returning home from dinner and coolant was leaking through a crack in the coolant reservoirs. Using a VAG-COM yielded several Fault Codes. One of which attracted me the most was the Coolant Fan Control Module (J293). I noticed when turning on the car, both fans do not engage. While the car is idling in park position, and AC is turning on, only the driver's Fan is spinning and the Passenger Fan is not. What could be going on here?

I've already ordered a Genuine Coolant Reservoir and Cap from Audi. Other Fault Codes I received which were related to this are the following:

19497 (P3041) - Powertrain Databus: Implausible Engine Temp. Message from Inst. Panel (No Signal / Communication - Intermittent)

00735- Potentiometer in Positioning Motor for Air recirculation Flap (G143) / Open or Short to Plus - Intermittent

01039 - Coolant Temperature Sensor (G2) / Open or Short to Plus - Intermittent

18339 - Coolant Fan Control Module (J293) : Malfunction / P1931 - 002 - Lower Limit Exceeded - Intermittent

Vehicle Details:
Audi A6 C5 Quattro (2004) 3.0T
Miles: 139,286 Miles

 

Do you all think starting with replacing the reservoir was the right thing to do?
I'm trying not to spend much. This problem just surfaced yesterday, but I'm sure the problem was building up (like a volcano); the temperature gauge has been acting funny for the past few weeks, where the gauge occasionally went from the middle to zero

I'm sure one of the sensors (if not both temp sensors) will have to be eventually replaced as well.

I'm hoping the passenger fan is functional.

Perhaps everything will be resolved as long as I replace the coolant reservoir? What do you all think? Please let me know. Thank you.

 

Will simply replacing the Coolant Reservoir resolve this problem? Is this a good first step to take?

 

You should replace the fan module and temp sensor. The leak is most likely that your car is starting to overheat and so excessive pressure is being release through the reservoir cap.

 

Thanks for your reply

I'm suspecting the Coolant Reservoir has been cracked between the min and max lines for quite some time now and the pressure the engine is working with is obstructing the real engine temperature values.

I'm going to replace the Reservoir, Cap, and Coolant Temp Sensor first, as these are the easiest to replace, judging from YouTube videos and forum tutorials. Hopefully this will eradicate the problem once and for all.

The FCM is the last thing I want to think about since it requires stripping the electrical wiring from the existing FCM that is directly connected to the Driver Side fan. I wonder why Audi did this.

The G62 sensor I heard is a pain in the butt to replace as well.

I really hope I don't have to escalate this to a mechanic, it costs too much to repair, I might as well try this myself. Would this be a wise thing for me to do?