DPF Diagnostics

DPF light on?
Regens keep
failing?

Mobile DPF fault diagnostics, cleaning and forced regeneration, at your driveway or depot across South & West Wales — finding and fixing the real cause before it blocks solid.

Mobile — We Come To You Fully Insured Diagnostics & Repair Only
DPF warning light illuminated on a car dashboard
Driveway-Ready. Fixed Properly.
DPF filter removed from a diesel exhaust system for inspection
The Basics

What a DPF does, and why it blocks

The Diesel Particulate Filter traps soot from the exhaust before it can leave the tailpipe, then periodically burns it off in a process called regeneration. It's a legal requirement on the vast majority of modern diesels.

Regeneration needs sustained higher engine speeds to complete properly — lots of short, low-speed journeys are the single biggest cause of a filter that never gets the chance to clear itself and gradually blocks solid.

We connect to the ECU, check soot loading and differential pressure data, and work out whether the fix is a forced regeneration, a proper clean, or a component fault causing the problem in the first place.

30-120
Minute Diagnostic & Repair
All
Major Diesel Manufacturers
1,800+
DPF Faults Resolved
MOT
Safe, Compliant Repairs
Common Faults

Not every DPF warning means the same thing

Soot Loading

Blocked / Clogged Filter

Built-up soot beyond the point a normal regeneration can clear, usually from repeated short journeys.

Regeneration

Failed Forced Regens

A regeneration that starts but doesn't complete, often due to interrupted journeys or an underlying fault elsewhere.

Sensors

Differential Pressure Sensor

A faulty sensor reports incorrect soot loading to the ECU, triggering warnings or blocking regeneration unnecessarily.

Sensors

Exhaust Temperature Sensors

Faulty temperature sensors can prevent the ECU from safely reaching regeneration temperature.

Oil Dilution

Fuel-in-Oil From Failed Regens

Repeated incomplete regenerations can dilute engine oil with unburnt fuel, needing an oil change alongside the DPF fix.

Knock-On Effects

EGR-Related Soot Increase

A faulty EGR system can increase soot production, accelerating DPF blockages — worth checking both together.

The Process

Four steps to a properly cleared filter

Step 01

Book Your Slot

Tell us the warning light or symptoms and we'll get a visit booked in quickly.

Step 02

We Come To You

Home, work or depot — anywhere across South & West Wales, no towing to a garage.

Step 03

Diagnose & Regenerate

Soot loading and sensor data reviewed, then a forced regen, proper clean, or component repair as needed.

Step 04

Test & Confirm

Soot loading re-checked and warning status confirmed clear before we leave.

Book a Diagnostic
Related Services

Other faults sorted in the same visit

Diagnostics

Full Fault Diagnosis

A complete system scan if you're not sure what's actually wrong yet.

Emissions

EGR Solutions

Sticking or faulty EGR valves diagnosed and resolved at the source.

Emissions

AdBlue Solutions

Persistent AdBlue faults and dosing errors resolved.

Sensors

Lambda / O2 Sensor

Faulty oxygen sensor faults diagnosed for smoother running and accurate fuelling.

Why WCH Tuning

Fixed properly, so it doesn't block up again next month.

DPF faults are frustrating because a quick reset rarely lasts if the underlying cause isn't addressed. We diagnose why it's blocking in the first place, then clear or repair it properly.

Genuinely Mobile

We bring the full diagnostic and regeneration kit to your driveway or depot — no towing or waiting for a garage slot.

All Major Diesel Manufacturers

From daily-driver diesels to fleet vehicles, we work on DPF systems across the vast majority of makes and models.

MOT-Safe, Compliant Repairs

Every repair keeps your DPF fully functional and compliant — nothing that risks an MOT failure.

Straight-Talking Diagnosis

A clear explanation of what's actually wrong before any work starts, with no pressure to over-spend.

In Their Words

From drivers fed up with the DPF light

★★★★★

"Filter was blocked solid from years of short school-run trips. Forced regen and a proper clean sorted it in an hour."

— Driver, Swansea
★★★★★

"Turned out to be a faulty pressure sensor, not the filter itself. Saved me from an unnecessary replacement."

— Driver, Carmarthenshire
★★★★★

"Checked the EGR at the same time and found that was making the DPF block faster. Both fixed properly in one visit."

— Driver, Pembrokeshire
Coverage

Mobile across South & West Wales

If you're within reach of these areas, we'll come to you. Based further afield? Get in touch — we regularly travel beyond our core patch for the right job.

Cardiff Newport Bristol Bridgend Merthyr Tydfil Pontypridd Aberdare Caerphilly Barry Cwmbran Blackwood Ebbw Vale Abergavenny Ross-on-Wye West Wales Swansea Neath Port Talbot Llanelli Carmarthen Haverfordwest
Map showing WCH Tuning's mobile coverage across South and West Wales
Questions

Before you book

No. Removing or gutting a DPF is illegal on any road-registered vehicle in the UK under the Road Vehicles (Construction and Use) Regulations, causes an automatic MOT failure under the smoke and visual checks introduced in 2014, and can result in prosecution for the vehicle owner and whoever carried out the work. We offer diagnostics, cleaning and regeneration only, restoring the filter to proper working order.

Usually a pattern of short, low-speed journeys that never let the filter reach regeneration temperature for long enough. It can also be a sensor fault or an EGR issue increasing soot production — we'll check both before recommending a fix.

Most blockages can be cleared with a forced regeneration or a proper clean. Replacement is only needed where the filter itself is physically damaged or has melted internally — we'll always try the less expensive fix first.

Diagnosis typically takes 30–60 minutes. A forced regeneration or clean usually adds another 30–60 minutes, so most visits are completed within two hours depending on how blocked the filter is.

Yes — MOT testers check for excessive smoke and will fail a car if the DPF appears to have been removed or tampered with. Keeping the filter working properly, as we do, avoids that risk entirely.

Optimised Performance

Get your vehicle back in tip top condition with WCH Tuning.
Search