What DPF diagnostics involves
We read fault codes across the engine and related modules, then look at the data the control unit uses to judge the DPF: differential pressure, calculated soot and ash loading, exhaust temperatures and the regeneration history where it is available. Comparing those values tells us whether the filter really is blocked, whether a sensor is giving a false reading, or whether regenerations are being prevented.
We also look at the usual contributors to soot: EGR behaviour, boost, injector-related data, thermostat and coolant temperature, and any additive system on vehicles that use one.
- 01Fault codes and freeze-frame data
- 02Differential pressure sensor and pipework
- 03Exhaust gas temperature sensors
- 04Calculated soot and ash load
- 05Regeneration history and conditions
- 06EGR, boost and injector-related data
After the diagnosis
Once we know the cause we explain the options: repairing a sensor or pipe, addressing an EGR or injector fault, a forced regeneration, a clean, or replacement where the filter is damaged. You receive a quote for the agreed work before anything else is done.
Diagnostics is also the right first step if you are considering a remap on a diesel that has had DPF problems. Tuning a vehicle with an unresolved DPF fault is not something we recommend.
How we approach DPF diagnostics
Diagnosis comes before parts or software. We read stored fault codes, look at live data such as sensor readings, temperatures and pressures where the system makes them available, and ask how and when the problem appears. A warning light describes a symptom that the control unit has detected; it does not always name the part that has failed, so the fault code is the starting point of the investigation rather than the answer.
Once we understand the likely cause we explain the findings in plain language and discuss the sensible options, which might be a repair, a clean, a software update, a replacement part or simply a change in how the vehicle is used. You receive a quote for the agreed scope before further work goes ahead. We will not recommend removing an emissions system as a fix for a road vehicle.
What to send us before booking DPF diagnostics
The quickest way to get useful advice is to send the registration and a short description by WhatsApp or through the quote form. Support and suitability vary by engine, gearbox, control unit and software version, so a registration lets us check the right information instead of guessing. Any estimate given remotely is provisional until the vehicle has been seen and the required checks are complete.
- 01Vehicle registration and approximate mileage
- 02Make, model and engine size, if known
- 03Any warning lights, messages, symptoms or fault codes
- 04Existing remaps, tuning boxes or hardware modifications
- 05How the vehicle is used — commuting, towing, short trips or heavy loads
- 06Whether the vehicle is currently in limp mode or will not start
Emissions equipment and the law
We do not offer DPF, EGR or AdBlue/SCR deletes for vehicles intended for public-road use. Removing or disabling emissions controls can make road use unlawful, and a missing factory-fitted DPF is an MOT failure. An “off-road” disclaimer does not make a road vehicle compliant. Non-road enquiries are considered only where the intended use can be verified, and are assessed individually against the applicable requirements.
Read the government guidance on diesel particulate filters ↗
Visiting the workshop for DPF diagnostics
All work is carried out at our single workshop at Unit 2, Lancaster Works, Kingsbridge Road, Manchester M9 5SP. We do not run a mobile remapping service and we have no other branches, so every DPF diagnostics enquiry is booked into the same Manchester workshop. Visits are by arrangement: please call or WhatsApp before travelling so we can confirm the vehicle, the time and what the visit will involve.
Access is through the black gate. Call when you arrive so we can let you in, then keep left towards the rear of the site. We are open Monday to Friday 8am–6pm and Saturday 8am–1pm, and closed on Sunday. If the vehicle is in limp mode, showing a serious warning or will not start, tell us before setting off so we can talk about whether it is sensible to drive it or whether transport should be arranged.