Why Does My DPF Light Come On More in Winter?

What a DPF does

A diesel particulate filter (DPF) sits in the exhaust of most modern diesel cars and vans. It traps soot so it does not come out of the tailpipe. Over time the filter fills up, and the car burns the soot off in a process called regeneration.

Regeneration needs the exhaust to get very hot, which usually means a steady drive at higher speed for a while. If that never happens, the soot keeps building up and the DPF warning light comes on.

Why winter makes it worse

In winter, engines take longer to reach full temperature, and many people make shorter trips. A school run or a quick drive into Birmingham in traffic rarely gets the exhaust hot enough to regenerate.

Regenerations also get interrupted when you switch off mid-cycle. Do that a few times and the filter can go from partly full to blocked.

What to do when the DPF light comes on

Check your handbook first, as the advice varies between manufacturers. Often it recommends a steady drive at motorway speed for 15 to 20 minutes to let the car regenerate. If the light goes out, the filter has cleared.

If the light stays on, flashes, or comes with another warning light or a loss of power (limp mode), stop trying to clear it on the road and get it checked. Carrying on can leave the filter so full that it can no longer be regenerated.

The underlying fault is often something else

A DPF that keeps blocking is sometimes a symptom rather than the problem. Faulty pressure sensors, a sticking EGR valve, injector problems or the wrong engine oil can all stop the filter working properly.

At ER Automotive we read live data first to see what is actually going on, so you are not paying for a clean or a new filter that will block again a month later.

DPF help in Smethwick

If your DPF light is on, call ER Automotive on 0121 461 6097 or book online. We carry out forced regenerations and DPF cleaning, and we will tell you honestly whether the filter can be saved.