What Does the DPF Light Mean?
Your diesel particulate filter traps soot from the exhaust. To stop it filling up, the engine periodically burns the soot off in a process called regeneration. This needs the exhaust to be hot for a sustained period, usually during steady driving at higher speeds. Most of the time this happens without you noticing.
When the DPF light comes on, the filter has built up more soot than it can clear on its own. If it keeps filling, the car may go into limp mode to protect the engine. At that point a normal drive is unlikely to clear it, and the risk of needing a costly replacement filter goes up.
Common Signs of DPF Problems
- DPF warning light on, or flashing
- Engine management light or glow plug light alongside it
- Reduced power or limp mode
- Cooling fan running after you switch off
- Idle speed higher than usual
- Worse fuel economy than normal
- A strong smell or more smoke than usual
See your exact gains first
Put your reg into the gains checker for your Stage 1 figures.
Why DPFs Block Up Around Cambridge
Short journeys are the main cause. School runs, commutes into Cambridge city centre and stop-start traffic rarely let the exhaust get hot enough to regenerate. Each failed or interrupted regeneration leaves more soot behind.
Other causes include a sticking EGR valve sending soot back through the engine, faulty pressure sensors giving the wrong reading, boost leaks, and worn injectors. Fixing the DPF without fixing the cause usually means the light comes back within weeks, so we always look at the whole picture.
How We Diagnose DPF Problems
Read codes and soot load
We check the fault codes and the soot and ash levels the ECU has recorded, along with how many regenerations have failed.
Check the sensors
A faulty differential pressure sensor can report a blocked DPF when it is not. We look at the live readings to rule this out.
Look for the root cause
We check for EGR, boost and other faults that may be loading the filter. If a part needs replacing, we will tell you honestly, even if that means the job is not one for us.
Forced Regeneration Where Possible
If the soot load is not too high and there is no underlying fault, we may be able to run a forced regeneration with diagnostic equipment. This burns off the soot while the vehicle is stationary and can clear the problem without further work.
A forced regen is not always possible or safe. If the filter is too heavily loaded or the cause is still present, it may fail or the problem may return quickly. We will explain the options before we start.
The DPF Software Solution
For vehicles with repeated DPF problems, we offer an ECU software DPF solution from £180, or £40 extra when added to a Stage 1 remap (£290 combo). We take a full backup of your original software first, so the work is fully reversible.
This solution is typically sold for off-road, export or motorsport use in many markets, so please be aware of MOT and emissions rules. We will never promise an MOT pass. For more detail on this service, see our DPF delete page.
Vehicles We Cover
- VW, Audi, Skoda and SEAT TDI
- BMW and Mercedes diesels
- Ford TDCi and EcoBlue, including Transit
- Vauxhall CDTi, Vivaro and Movano
- Peugeot and Citroën HDi and BlueHDi
- Land Rover and Range Rover diesels
- Iveco Daily, Fiat Ducato and motorhomes
We are mobile across Cambridgeshire with no travel charge, including Ely, Huntingdon, St Neots, St Ives, Newmarket and Peterborough, or visit our Milton workshop.