Skoda AdBlue Repair and SCR Diagnostics in Cardiff

A surprising number of the Skoda AdBlue faults we see were caused by the refill rather than by a broken part. AdBlue is a precisely specified fluid and the system that meters it is intolerant of anything that is not exactly that. How the tank gets filled, what goes into it and what the fluid does while it sits there matter more than most owners are ever told.

Topping it up without causing a fault

AdBlue is not an additive and it is not something where a near enough equivalent will do. It is made to a single international standard, ISO 22241, and anything outside that specification can damage the dosing system and the catalyst behind it. Buy sealed containers or use a proper forecourt pump, and check the date on the container, because it does have a shelf life and it degrades in heat and sunlight.

The other common cause is contamination introduced during the fill. A funnel that has had anything else in it, a jerry can kept in the garage for other purposes, or diesel splashed into the AdBlue filler are all enough to cause real damage. The AdBlue filler is usually next to the diesel filler and is normally blue, and putting diesel into it is an expensive mistake that we do see. If that happens, do not start the engine. Call us and have it recovered, because running it is what turns an inconvenience into a bill.

Put in a decent quantity rather than a token amount. Some cars will not clear the warning or reset the range calculation until the level has risen enough for the sensor to register a genuine change, which is why a small splash sometimes appears to achieve nothing.

Crystals, short journeys and the injector

AdBlue crystallises into a white deposit when it dries, and the place that causes trouble is the dosing injector that sprays it into the exhaust. The system is designed to burn those deposits off at exhaust temperature, but a car doing short, cold journeys around Cardiff may never get hot enough for long enough. Deposits then build up, the spray pattern goes, and the system reports that it is not dosing correctly.

White crusty residue around the injector, the tank or any of the lines is worth acting on early. At that stage it is usually a clean and a seal. Left alone it becomes a blocked injector and a considerably larger job. If your Skoda lives on short runs, an occasional longer drive genuinely helps this system as well as the DPF.

P20E8 and the countdown

P20E8 means reductant pressure too low, so the system could not build the pressure needed to dose. That points at the delivery side, which could be the pump, a crystallised injector, a line, or the fluid itself. Once a fault is stored the car will start counting down to a no restart, and topping the tank up at that point does not clear it. The fault needs diagnosing and clearing properly, and if the cause is still there it will return.

Do not run the countdown to the wire. At zero the engine will not restart and it becomes a recovery job. We do not delete or emulate AdBlue systems, it is an emissions and MOT matter, but we will find the fault and fix it. See our AdBlue repair page for all makes and Audi AdBlue diagnostics.

Contact us

If you need any advice with regards to your Skoda AdBlue systems on your vehicle, get in touch and book your vehicle in for a diagnosis. Our experienced mechanics can repair any Skoda AdBlue fault and reset the system. Use the contact form below or contact details displayed to contact us. We are happy to help.

A1-Diagnostics and ECU Repairs
64 Sloper Road
Leckwith,
Cardiff
CF11 8AB

Tel: 02920 220 380

Opening Times

Mon – Fri: 8:00am – 6:00pm

Email: info@a1-diagnostics.com