It’s cold outside; you went for only a short trip up the road, the engine is not even warm yet but when you shut the engine off and get out you notice the cooling fans buzzing away like they do on a hot summer day. This can’t be normal, right?
This is a common concern with new Clean Diesel owners and rightfully so. The thought of walking away from your Volkswagen with the cooling fans buzzing away leaves most people with images in their heads of dead batteries and tow trucks. Rest assured—this is in fact normal operation. The after-running of the cooling fans is deliberate and can sometimes last up to 16 minutes after switching the engine off. The after-running process prevents excessive engine compartment temperatures caused by the diesel particulate filter regeneration cycle. The cooling fans may continue to run even after driving less then 3.2 km.
Technically-speaking, this process involves rapidly heating up the diesel particulate filter to temperatures nearing 650 degrees Celsius in an effort to burn off trapped soot inside the diesel particulate trap. Since the vehicle does not know you are only going on a short trip, it may start this process just before you arrive at your destination and now that engine is switched off and the vehicle is stationary the system will self-activate the cooling fans at high speed in an attempt to bring down those high temperatures now trapped below the hood. When the temperature falls into acceptable range the fans will stop automatically.
Bonus point: some new TDI owners have also reported an odd odour describing it as a “burning smell”. This burning smell is also a byproduct of the regeneration cycle and caused by the rapid burning off of the accumulated soot in the particulate filter and is considered normal operation as your Volkswagen is doing everything it was designed to do and doing its best to keep the air we breathe as clean as possible.
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We hope this information is valuable! Please contact Mike directly if you have any questions on this; it’s our pleasure to help. + Email
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