Is a blocked DPF always the DPF's fault?

No. Sensor faults, EGR problems, boost leaks, injector issues and short-journey use can all cause a DPF to load up. That is why we diagnose before recommending regeneration or replacement.

Do you work on vans as well as cars?

Yes, we regularly work on light commercial vehicles and diesel vans alongside cars.

DPF & Diesel

Diesel Diagnostics

Modern diesels combine high-pressure fuelling, turbocharging, exhaust gas recirculation and after-treatment. When one part of that system drifts, the symptoms usually show up somewhere else.

Diesel in limp mode?

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Common diesel complaints

Repeated DPF warnings or blocked DPF messages
Limp mode and sudden loss of power
Smoke, rough running or a knocking injector
Poor starting when hot or cold
EGR valve and cooler faults
Turbo and boost pressure problems
Glow plug and preheat faults
Excessive oil consumption or oil level rising

How we approach diesel faults

We look at the whole system rather than a single code. Boost and exhaust pressures, fuel rail pressure, injector correction values, EGR position and after-treatment temperatures all get checked so the underlying cause is identified rather than a downstream symptom.

Driving conditions matter

Short, cold journeys are hard on diesel after-treatment systems. Part of diagnosis is understanding how the vehicle is used, because that often explains recurring DPF and EGR problems and changes what we recommend.

Frequently asked questions

Diesel running badly?

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Our work

Recent jobs from our workshop

Photographs taken during work carried out at our Iver workshop.

Piston removed during an engine strip, showing carbon build-up
Soot-blocked EGR port removed for cleaning
Inlet manifold off — carbon build-up in the runners
Carbon-choked inlet port found during diagnosis

Ford & Transit

Related Ford and Transit work

Wet belts, diesel diagnostics and DPF work on Ford cars and Transit vans — each page covers a different part of the job.

Ford Repairs & ServicingFord cars and vans make up a good share of the work that comes through our Iver workshop. This page covers how we approach Ford repairs generally — the belt-in-oil pages go into the timing and oil pump drive work in detail.Read more Ford Transit Custom RepairsThe Transit Custom is a working van, and the faults we see reflect that — high mileage, heavy loads and a lot of short urban journeys. Here is what tends to come in, and how we approach it.Read more Ford Wet Belt ReplacementFord's belt-in-oil designs are among the most common wet belt systems on UK roads, and among the most talked about. We replace them properly, including the oil pump drive.Read more Ford EcoBlue Wet Belt ReplacementEcoBlue diesels use a belt-in-oil timing drive. Owners often first hear about it when an oil pressure warning appears — which is the worst time to find out.Read more Ford Transit Custom Wet Belt ReplacementThe Transit Custom is one of the hardest-working vans in the country, and its belt-in-oil timing drive is one of the jobs owners cannot afford to leave.Read more DPF DiagnosticsA DPF warning is the end of a chain of events, not the start. Finding out why the filter is loading up is the part that saves money.Read more Timing Belt Replacement in IverThe timing belt keeps the crankshaft and camshafts turning in step. If it fails in service, the damage is usually to the engine rather than the belt.Read more

Advice

Helpful reading on this fault

DPF light on? What it means and what not to doA DPF light is a warning, not a failure. What you do in the next few hundred miles decides whether this is cheap or expensive.Read more DPF cleaning or replacement — which do you need?Cleaning a filter that blocked for a mechanical reason just buys time. Start with why it blocked.Read more Signs your DPF is blocking upA DPF rarely blocks without warning. These are the signs worth acting on before it becomes a replacement.Read more

Symptoms

Symptoms that often lead to this repair

Look up what your car is doing and read what it commonly means.

Car stuck in limp modeLimp mode is a protection strategy, not a fault in itself. The control unit has seen a reading it does not trust and has reduced power to keep things safe.Read more DPF warning light onThe DPF light means soot has built up beyond the level the system is happy with. Whether a drive will clear it depends on why it built up.Read more Glow plug (coil) light flashing on a dieselOn many diesels the coil symbol doubles as an engine fault warning. A flashing light usually means a stored fault, not necessarily a glow plug.Read more Black smoke from a diesel exhaustBlack smoke is unburnt fuel. On a modern diesel with a DPF it usually also means extra soot heading into the filter.Read more Car losing power when acceleratingLoss of power is either a fuelling, air or protection issue. Live data under load is what separates them rather than guesswork.Read more Car hard to start when coldCold starting depends on battery condition, fuel pressure, compression and, on diesels, glow plug operation. Cold weather exposes weakness in any of them.Read more Turbo failure symptomsTurbos rarely fail without a reason. Oil supply, oil condition and blocked exhaust flow are common contributors, and replacing the turbo alone can repeat the failure.Read more EGR valve symptomsEGR valves soot up over time, particularly on cars used for short journeys. The symptoms overlap with several other faults, so testing matters.Read more Car jerking when acceleratingJerking under load usually means the engine is briefly not getting the fuel, air or spark it needs — live data while driving is the quickest route to the cause.Read more

You may also need

DPF DiagnosticsA DPF warning is the end of a chain of events, not the start. Finding out why the filter is loading up is the part that saves money.Read more DPF RegenerationRegeneration burns accumulated soot out of the filter. It is effective when the filter and the engine are in a fit state — and pointless when they are not.Read more EGR Valve Repair & ReplacementThe EGR system recirculates a measured amount of exhaust gas back into the engine. When it sticks, everything downstream suffers — including the DPF.Read more Turbo ReplacementTurbo failure often has an underlying cause. Oil supply, restriction and boost control are checked first — otherwise the new turbo goes the same way as the old one.Read more Injector Diagnostics & Injector-Related RepairsInjector faults imitate a lot of other problems. Testing the injector data before replacing anything avoids fitting expensive parts the engine did not need.Read more Car Diagnostics & Fault Finding in IverA warning light tells you something has been detected — not what has failed. We diagnose the vehicle first so the repair that follows is the repair the car actually needs.Read more

Talk to us about diesel diagnostics

Based in Iver, covering West London, Berkshire and South Buckinghamshire. Send your registration and we will quote for your vehicle.

Call 07440 140340 WhatsApp us