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Are AdBlue Systems Problematic or have Australian Technicians not been provided with the right training to work on AdBlue systems? 

Recently at The Automotive Clinic we had a trade customer bring us a problematic 2019 Mercedes Benz Vito van. AdBlue issues are notorious for being problematic, this we believe is for a few reasons, firstly this is because these systems are still relatively new to Australia. Technicians haven’t had the chance to be trained and properly understand how AdBlue and SCR (selective catalyst reduction) systems work yet. Secondly as these systems are actually quite basic but very control module dependent they get a bad rap for being hard to diagnose.

Back to our vehicle at hand

This Mercedes was running and driving perfectly, the EML was on the dash and we had a stored code for AdBlue over usage. This fault in of itself isn’t much detail, it’s a common fault that is set when there is an underlying issue with an AdBlue system. 

Our next step in this diagnosis was to test drive the vehicle and view live data. On our extended test drive we noticed absolutely no activity from our NOX sensors, they were not waking up and reading, we had no stored faults in the NOX sensors themselves so our only reason for why the system would not activate would be due to the engine fault. 

Diving deeper into this specific AdBlue over usage fault the main component in this system would be the AdBlue injector, looking into the Adblue injector or (metering valve), this is a computer controlled injector that controls how much AdBlue is injected into the system. We now have a good idea that our main fault is with how much AdBlue is being used through this injector. 

Our next step in this situation was to consult our customer, as parts had been replaced on this system we needed to know what was replaced, after having a conversation with our customer we determined that this vehicle had already had an injector replaced for this fault with an OEM unit. 

Knowing this we were then able to hook up our Mercedes benz dealer diagnostic equipment and re configure the AdBlue metering valve. This essentially resets the valve’s learned values and re-programs it to the vehicle’s ECU. This is where having dealer level diagnostic equipment comes in, this task would not be able to have been completed with a standard aftermarket tool, the only other option would be to send the vehicle to the Mercedes dealership for an expensive programming session. 

After completing this task we were able to complete another extended 45  minute test drive, after about 15 minutes our SCR system was alive and operating correctly !

Dealer Level tooling and equipment is a must 

This case study highlights that workshops that wish to effectively diagnose and repair computer controlled systems in modern vehicles, need to have access to dealer level tooling 

Contact The Automotive Clinic today to have your vehicle diagnosed by the experts