Quick answer
Fixing DPF issues often starts with a forced or active regen to burn soot. If that fails, professional cleaning or replacing the filter may be needed. Also address underlying causes, like short trips or engine faults, to prevent recurring blockages.
Detailed answer
Diesel Particulate Filter (DPF) headaches usually revolve around soot build-up. Solve that, and you’re on your way to smoother diesel motoring. But sometimes it’s not just the filter—it’s how you drive or a hidden mechanical fault. Below is a roadmap for fixing common DPF problems.
1. Check the Dashboard Warnings
If your DPF light is on, see if the car is still driveable. Often, you can attempt an active regeneration by taking a 20–30-minute motorway run at moderate RPM. The engine control unit (ECU) may automatically raise exhaust temps to burn off soot. If the light goes out afterward, problem solved.
2. Attempt a Forced Regeneration
When normal driving won’t do the trick, a forced regen can be initiated at a garage or with the right scan tool. The engine is revved at high idle for 10–20 minutes, incinerating the built-up soot. This typically works if the filter is partially clogged but not physically damaged. Expect a small garage fee, but it’s cheaper than a new DPF.
3. Professional DPF Cleaning
If the forced regen doesn’t fix it—or blockages are severe—removing the DPF for a proper clean is next. Special machines use chemicals, water, or ultrasonic agitation to break down soot and ash. Cleaning can restore the filter to near-new condition. Costs vary from about £200 to £400, far less than a fresh DPF.
4. Replacement
A last resort if your filter is cracked, melted, or heavily ash-laden beyond salvage. Replacement can run £700–£2,000 depending on brand and model. Before paying, confirm the filter is truly unfixable. Some unscrupulous places push replacements unnecessarily.
5. Address Root Causes
Why did the DPF clog in the first place?
– Short Trips: Without longer journeys, the exhaust never reaches high enough temps. Try scheduling weekly or bi-weekly motorway runs.
– Engine Faults: Leaking injectors, turbo seal leaks, or a faulty EGR valve produce extra soot. Fix them or your fresh filter will clog again soon.
– Wrong Oil: High-ash oils accelerate residue buildup. Switch to the manufacturer’s recommended low-SAPS oil.
6. Driving Habits
After a fix, re-examine your routine. If you rarely exceed 50 mph, the DPF can keep clogging. Some people do a “DPF-friendly drive” once a week—20 minutes at 2,000–3,000 RPM—to let regeneration happen. Keep an eye on the dash for regen cues: idle changes, a hot exhaust smell, or a slightly higher rev at idle.
7. DPF Additives
Fuel additives can lower the soot burn temperature, helping prevent blockages. They won’t revive a filter that’s already severely clogged, but they may help keep a clean or partially cleaned filter in good shape.
8. Don’t Delete
Tempting as it sounds, removing the DPF is illegal on public roads and an MOT fail in the UK.
In Summary
To fix DPF problems, start with attempts at regeneration—either a decent motorway run or a forced regen. If that fails, consider professional cleaning or, if needed, replacement. Crucially, tackle the underlying issues that caused it to clog in the first place, whether that’s your driving style, incorrect oil, or engine malfunctions. Take these steps, and you’ll dramatically reduce the chance of facing the same DPF woes a month later.
