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When the SCR system fails, the car warns you with a countdown of remaining starts: once it runs out, the engine will no longer restart. It pays to act at the first messages, not on the last available start.

Typical symptoms

• “Repair AdBlue system” message or remaining starts on the display
• Reduced power
• Engine light and specific AdBlue light
• Abnormal additive consumption or no consumption at all

Most common causes

• Crystallisation of urea in the injector or the line
• Failed dosing pump or clogged internal filter
• Downstream NOx sensor failure (a very frequent cause)
• Tank level or quality sensor
• Poor-quality or contaminated AdBlue
• Failed line heater: problems only in freezing weather

What to do

• Do not wait for the last start: after the lock-out the repair is needed anyway
• Use additive that meets the standard and do not store it too long
• Have the faults read: they immediately distinguish NOx sensor, pump and injector

Software deactivation of the SCR system is not permitted on the road: it is reserved for off-road, competition or export vehicles.

How MasterTuning helps

We check the component with real measurements, not by elimination: flow rates, pressures, corrections and signals read directly from the ECU. We repair, replace and recalibrate the software when needed. Centres throughout Italy.

Read more: what is ECU remapping · vehicle database · find an installer

Want an accurate diagnosis? Contact MasterTuning and book at your nearest centre.

Frequently asked questions

What happens when the AdBlue starts run out?

The engine will not restart until the system is repaired and the fault cleared with the diagnostic tool.

How much does it cost to repair the AdBlue system?

It depends on the component: a NOx sensor or a crystallised injector cost much less than the complete pump. Diagnosis avoids unnecessary replacements.

Can AdBlue be deactivated?

Not on vehicles used on public roads: deactivation only concerns off-road, motorsport or export use.