SCR system • Repair or replace • Cost guide
SCR System Repair vs Replacement Cost: What You’ll Really Pay
Been quoted a four-figure bill for an SCR fault?
Before you agree to a full replacement, this guide breaks down repair vs replacement costs,
what usually fails, and how to choose the right fix without guesswork.
An SCR fault often triggers panic.
Dealers usually jump straight to replacement.
That is the most expensive route.
In many cases, the SCR system does not need replacing.
A targeted repair can restore correct readings and stop the warnings for far less money.
The key is knowing which part failed and why.
This guide helps you answer one question
Can your SCR fault be repaired sensibly, or is replacement the only option?
What the SCR system actually includes
When someone says “the SCR has failed”, they rarely mean one single part.
The system is made up of several components that work together.
- AdBlue tank and pump
- Dosing injector
- SCR catalyst
- Upstream and downstream NOx sensors
- Temperature and pressure sensors
- Wiring and control modules
A fault in any one of these can make the ECU think the whole SCR system is not working.
That is where unnecessary replacements often start.
SCR repair vs replacement: real-world cost ranges
| Option | Typical cost range | What it usually involves |
|---|---|---|
| Targeted SCR repair | £150 – £600+ | Sensor, wiring, dosing, or pump-related fixes |
| Partial system replacement | £600 – £1,200+ | Tank assembly, pump unit, or injector assembly |
| Full SCR replacement | £1,500 – £3,000+ | Catalyst, sensors, labour, coding, dealer time |
Prices vary by vehicle, access, and fault path.
The point is the gap between repair and replacement can be huge.
When SCR repair usually makes sense
Sensor-related faults
NOx sensors commonly fail or drift.
Replacing the faulty sensor often restores correct SCR readings.
Dosing or pump issues
Weak pumps, blocked lines, or crystallisation can reduce dosing without damaging the catalyst.
Wiring and connector faults
Intermittent SCR faults often come down to wiring damage or water ingress.
These scenarios are covered under our
SCR system repair
service.
When full SCR replacement may be unavoidable
- Severe catalyst damage or internal blockage
- Long-term driving with unresolved dosing faults
- Repeated overheating or contamination
- Confirmed internal SCR efficiency failure
A proper diagnostic confirms this.
Guessing leads to expensive mistakes.
Why diagnostics decide the bill
Without diagnostics, replacement looks safer.
With diagnostics, repair often becomes obvious.
Our
mobile diagnostics
check live NOx readings, dosing values, temperatures, and fault history.
That shows whether the SCR catalyst is truly failing or just being blamed.
Before you replace the SCR, get it checked properly
Many SCR faults can be repaired for a fraction of the cost.
One visit can save you thousands.
