A top mechanic has warned diesel owners risk damaging a vital component and forcing costly repairs by making a simple error this Spring. Craig, a leading mechanic at Walsall Wood Tyre and Service, stressed trying to cut corners with a vehicle’s AdBlue system could dramatically backfire.

He warned pouring in water instead of AdBlue solution could cause havoc with vehicles and will likely lead to fault codes. He suggested garages will then charge motorists a hefty amount to diagnose and fix the issue in a major blow for owners. Craig and Walsall Wood issued the advice on TikTok where they post regular advice and feedback to confused road users. A motorist asked: “Saw an old video you made about AdBlue. My question is would it know if I just added water? And would it hurt? Craig replied: “Yes the car will know the difference because when it starts injecting the AdBlue and looking at the NOx levels in the exhaust it’s going to want to see a reduction in NoX.

"If you’re just spraying in water, you’re not actually going to get a reduction in NOx.

“That's gonna flag the usual fault code P2OEE which is going to give us a general denox system and then it's going to get very expensive for the garage to figure out what you’ve done before they actually have to start repairing the vehicle.

“So no, please, please, please guys do not put water in your AdBlue system. It will not work and I will charge you lots of money to fix it if you do.”

AdBlue systems are installed in many modern diesel cars manufactured after September 2015.

It's a simple solution used in the exhaust system of many models to help reduce harmful CO2 emissions at the tailpipe.

AdBlue is widely available across the UK with motorists able to pick it up at petrol stations, garages and motoring stores.

Motoring experts at the AA stress motorists should try not to run out of AdBlue with performance issues likely if tanks run dry.

They said: “If you run out of AdBlue while you’re driving, then the engine’s power and performance will be reduced to limit its emissions. Once you’ve stopped, you won’t be able to restart the engine if the AdBlue tank’s empty.”