Replacing a DPF is two jobs, not one: the mechanical swap, and the electronic set-up that tells the vehicle a new filter is fitted. Skip the second and the car will carry on managing the new filter as if it were the old, nearly-full one — regeneration never resets, and the new DPF can block within a few hundred miles. The set-up requires diagnostic equipment, which is why a new DPF should be fitted by a competent technician with DPF experience; failing to complete it properly can also invalidate the warranty.
Before anything else: the old filter blocked for a reason. Work through why DPFs block and fix the cause first — this is the single most important step on this page. Then record the new unit’s serial number (six letters, pin-stamped on the body) before fitting; it’s needed for any warranty query.
Removal
- Let the exhaust cool fully, disconnect the battery earth terminal, and raise the vehicle securely on a ramp.
- Photograph the installed unit for reference — DPFs often carry several sensors and pipes, and orientation matters.
- Identify every electrical connector and sensor on the unit: differential pressure pipes, exhaust-gas temperature sensors, oxygen sensors. Unplug connectors, free all wiring, and remove sensors carefully — they seize and are easily broken.
- Loosen all retaining nuts, bolts and clamps; use penetrating oil (or careful heat, with precautions) on anything seized.
- Support the rest of the system and remove the old unit — DPFs are bulky, so get help if needed.
Fitting
- Clean all mating surfaces thoroughly — no old gasket material, no corrosion at the joints.
- Use a new fitting kit wherever possible; corroded fixings lose thread and length.
- Inspect the rubber differential-pressure hoses for splits, perishing or blockages and renew if in any doubt — and make sure they go back the correct way round. Best practice is to renew the pressure pipes and the differential pressure sensor itself with the new filter; a false pressure reading will quietly ruin it.
- No exhaust paste, no sealant on joints ahead of the DPF — hardened paste destroys the filter core and voids the warranty.
- Fit the unit loosely first, align it with the rest of the system, then refit the sensors (snug, not over-tight) and reconnect all wiring, routing cables clear of hot surfaces.
- Check clearances all round, then tighten everything fully, taking care not to over-tighten.
- Reconnect the battery, start the engine and check every joint for leaks.
The ECU set-up — not optional
With the mechanical work done, connect a capable diagnostic tool and complete the manufacturer’s replacement procedure. Depending on the vehicle this includes:
- Clearing all stored fault codes — an active fault will prevent regeneration from ever initiating.
- Registering the new DPF — telling the ECU a replacement has been fitted.
- Resetting the ash and soot counters — otherwise the car believes the new filter is still full.
- Calibrating the differential pressure sensor to the new, clean filter.
- Reprogramming the additive level, on vehicles with a fuel-additive system, after topping up the tank.
- Performing a forced regeneration where the procedure calls for it, and confirming it completes.
Done properly, a quality aftermarket DPF behaves exactly as the original did when new. Done without the set-up, the best filter in the world will block again — which is why we repeat: use a garage with DPF experience and the right diagnostic kit.
Find the right filter for your vehicle with the part finder or browse the DPF range — and check our vehicle-specific notes for models with known extra requirements.