Will a forced regeneration fix my DPF?

A regeneration burns off soot, but it does not show why the soot built up. We report on the cause before any regeneration is attempted, so you can decide on the right fix.

Does the health check include cleaning or repairing the DPF?

No. The check finds the cause and gives you a written report with a price for any work. Regeneration and repairs are separate, and are done when you give us your written approval.

My diesel has an AdBlue warning. Is this the right check?

Yes. The check covers the AdBlue (SCR) system and the NOx sensor readings as well as the DPF and EGR.

Can you remove my DPF, EGR or AdBlue system?

No. We repair emissions systems; we never remove or disable them. Government guidance says removing a DPF will almost always make a car illegal for road use, and missing or modified emissions equipment is a Major defect in the MOT.

Will an engine warning lamp fail my MOT?

On a diesel first used from 1 July 2008, an engine warning lamp that shows a fault is a Major defect. Visible smoke of any colour from a car with a DPF is also a Major defect.

Diesel DPF, EGR and AdBlue

Book a DPF and emissions health check

The DPF and emissions health check tests why a diesel's particulate filter, EGR or AdBlue system is having trouble, using live data, backpressure readings and NOx sensor checks. You get a written report of the cause before any regeneration is attempted, so the reason for the problem is known before the filter is cleared.

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Last updated 12 November 2026

What is the DPF and emissions health check?

It is a booked check of your diesel’s emissions system that looks for the root cause of a problem. Clearing a blocked diesel particulate filter (DPF) does not tell you why it blocked. This check looks for the cause first, and you get a written report before any regeneration is attempted.

What does the check cover?

Live data. We read the engine and emissions system data, including soot load and regeneration history.
Backpressure readings. We take exhaust backpressure readings across the filter.
EGR. We check the exhaust gas recirculation system.
NOx sensors. We check the NOx sensor readings.
AdBlue (SCR). On cars with AdBlue, we check the selective catalytic reduction system.
Fault memory. We read the stored fault codes.

What do I get?

A written report that sets out what we tested, what we found and what we recommend, with a written price for any work. Any regeneration or repair comes after the report, and only when you give us your written approval.

What happens next?

Send the enquiry form on this page and tell us what the car is doing.
We contact you to confirm a booking.
We carry out the check and give you the written report.
You decide what to do. Nothing is done without your written approval.
After any repair, we check the system again.

What is not included?

regeneration and repairs, which are priced in the report
parts
removing or disabling a DPF, EGR or AdBlue system: we repair these systems, and we never remove or disable them

Is it legal to remove a DPF?

Government guidance on diesel particulate filters says removing a DPF will almost always make the vehicle illegal for road use.

How does the emissions system affect the MOT?

The MOT inspection manual treats each of these as a Major defect:

emission control equipment fitted by the manufacturer that is missing, obviously modified or obviously defective, including a DPF, EGR valve or SCR parts
evidence that the DPF has been tampered with
visible smoke of any colour from a car with a DPF
an engine warning lamp that does not work or shows a fault, on a diesel first used from 1 July 2008

A DPF that has been cut open and rewelded is rejected unless there is evidence of a valid reason, such as cleaning.

We carry out MOT tests in our own Class 4 bay.

Our promise on every job

Written approval before any extra work
Photographic proof of what we find
A promised update time
No surprise invoice
A test drive and verification where appropriate

Our service centre

Where will my car be looked after?

At our centre at 57 Great North Road, Welwyn Garden City, built so that waiting for your car is not wasted time.

Seven ramps and an on-site MOT bay
Three customer waiting areas
A co-working space with Wi-Fi
A multi-faith prayer room and quiet room
Lavazza coffee
Customer parking

Questions people ask us

Will a forced regeneration fix my DPF?: A regeneration burns off soot, but it does not show why the soot built up. We report on the cause before any regeneration is attempted, so you can decide on the right fix.
Does the health check include cleaning or repairing the DPF?: No. The check finds the cause and gives you a written report with a price for any work. Regeneration and repairs are separate, and are done when you give us your written approval.
My diesel has an AdBlue warning. Is this the right check?: Yes. The check covers the AdBlue (SCR) system and the NOx sensor readings as well as the DPF and EGR.
Can you remove my DPF, EGR or AdBlue system?: No. We repair emissions systems; we never remove or disable them. Government guidance says removing a DPF will almost always make a car illegal for road use, and missing or modified emissions equipment is a Major defect in the MOT.
Will an engine warning lamp fail my MOT?: On a diesel first used from 1 July 2008, an engine warning lamp that shows a fault is a Major defect. Visible smoke of any colour from a car with a DPF is also a Major defect.