{"id":26785,"date":"2026-07-19T17:39:11","date_gmt":"2026-07-19T16:39:11","guid":{"rendered":"https:\/\/www.cathive.co.uk\/advice\/why-dpfs-block\/"},"modified":"2026-10-01T19:33:50","modified_gmt":"2026-10-01T18:33:50","slug":"why-dpfs-block","status":"publish","type":"page","link":"https:\/\/www.cathive.co.uk\/nl\/advice\/why-dpfs-block\/","title":{"rendered":"Roetfilter verstopt? Pak eerst de oorzaak aan"},"content":{"rendered":"<p>A blocked DPF is a symptom, not a diagnosis. The filter blocks because something stopped <a href=\"\/advice\/what-is-a-dpf\/\">regeneration<\/a> from happening \u2014 a driving pattern, a vehicle fault, or both. Replace the filter without finding that something, and the new one can block in under 300 miles. This page is the checklist we&#8217;d want any garage (or determined owner) to work through first.<\/p>\n<h2>Start with the two easy questions<\/h2>\n<h3>How is the car driven?<\/h3>\n<p>Short, stop-start town journeys never get the exhaust hot enough for passive regeneration, and they keep interrupting active regenerations before they finish. Less obviously, gentle motorway cruising in a high gear on a 6-speed car can <em>also<\/em> run too cool \u2014 occasional harder driving in a lower gear is sometimes all that&#8217;s missing. If the driving pattern is the root cause, a new DPF plus the same driving pattern equals the same blockage \u2014 see <a href=\"\/advice\/looking-after-your-dpf\/\">looking after your DPF<\/a> for what actually helps.<\/p>\n<h3>How long was the warning light ignored?<\/h3>\n<p>The DPF light coming on means the filter is partially blocked and the car needs a sustained run to regenerate \u2014 at that stage the fix costs nothing. Around 75% full, only a garage-forced regeneration will recover it. Around 95%, the ECU puts the car into limp mode and the filter is usually beyond saving. The service history of the warning light tells you how the filter got to where it is.<\/p>\n<h2>Then check the systems regeneration depends on<\/h2>\n<p>Active regeneration only initiates when the ECU is happy with a long list of conditions. A fault in any of these can silently prevent it \u2014 often <em>without<\/em> being obviously connected to the DPF, and note that almost any unresolved fault that lights the engine-management lamp will stop regeneration from running at all:<\/p>\n<ul>\n<li><strong>Differential pressure sensor and its pipes<\/strong> \u2014 the sensor measures how blocked the filter is; split, kinked or blocked pressure pipes feed the ECU false readings. Best practice is to renew the sensor (and pipes if in doubt) with every new DPF.<\/li>\n<li><strong>Engine oil<\/strong> \u2014 two checks: is it the correct low-ash (low-SAPS) specification, and is the level high? An over-full sump suggests fuel dilution from repeated failed regenerations, and the oil must be changed.<\/li>\n<li><strong>Fuel additive system<\/strong> (where fitted) \u2014 an empty additive tank quietly disables regeneration; refilling usually requires the ECU to be reprogrammed to the new level.<\/li>\n<li><strong>EGR valve<\/strong> \u2014 a sticking or blocked EGR valve is one of the most common regeneration killers; clean it as a minimum, and on some vehicles replace it as a matter of course.<\/li>\n<li><strong>Glow plugs and their controller<\/strong> \u2014 on many vehicles (BMW especially) regeneration won&#8217;t initiate with a glow-plug system fault, and a failed controller often stores no fault code. When one glow plug fails, plugs and controller are usually replaced together.<\/li>\n<li><strong>Thermostat(s)<\/strong> \u2014 an engine running too cool never reaches the temperature window for regeneration. Some vehicles have two thermostats; both need to work.<\/li>\n<li><strong>Fuel vaporiser<\/strong> (Euro 5\/6 Fords and several PSA\/Fiat vans) \u2014 injects diesel into the exhaust to heat the filter; when it blocks, regeneration fails every time. See our <a href=\"\/advice\/vehicle-specific-fitting-notes\/\">vehicle-specific notes<\/a>.<\/li>\n<li><strong>Exhaust temperature and oxygen sensors<\/strong> \u2014 false temperature readings prevent or abort regeneration.<\/li>\n<li><strong>The wider engine<\/strong> \u2014 air-flow meter, turbo and engine wear, leaking injectors, air filter condition, and the upstream catalytic converter itself: regeneration relies on a working cat to generate heat, so a dead cat can block a DPF.<\/li>\n<\/ul>\n<h2>Then \u2014 and only then \u2014 replace the filter<\/h2>\n<p>With the cause fixed, fit the new filter following our <a href=\"\/advice\/fitting-a-dpf\/\">DPF fitting guide<\/a> \u2014 including the ECU set-up steps at the end, which are not optional. Find the right part for your vehicle with the <a href=\"\/#ch-make\">part finder<\/a> or browse the <a href=\"\/product-category\/dpf\/\">DPF range<\/a>.<\/p>\n<p><strong>Find the part:<\/strong> browse <a href=\"\/product-category\/pressure-pipe\/\">DPF pressure pipes<\/a>, <a href=\"\/product-category\/dpf\/\">replacement DPFs<\/a> and <a href=\"\/product-category\/catalytic-converter-dpf\/\">combined catalytic converter and DPF units<\/a>, or go straight to your vehicle: <a href=\"\/parts\/vauxhall\/vivaro\/\">Vauxhall Vivaro DPFs<\/a>, <a href=\"\/parts\/peugeot\/308\/\">Peugeot 308 DPFs<\/a>, <a href=\"\/parts\/citroen\/c4\/\">Citroen C4 DPFs<\/a>, <a href=\"\/parts\/ford\/focus\/\">Ford Focus DPFs<\/a> or <a href=\"\/parts\/\">all vehicles<\/a>.<\/p>\n<p><a href=\"\/advice\/\">&larr; Back to Help &amp; Advice<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Een verstopt roetfilter is een symptoom. Controleer eerst rijgedrag, lampje, drukleidingen, olie, additief, EGR, gloeibougies en sensoren.<\/p>\n","protected":false},"author":0,"featured_media":0,"parent":26778,"menu_order":70,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-26785","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.cathive.co.uk\/nl\/wp-json\/wp\/v2\/pages\/26785","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.cathive.co.uk\/nl\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/www.cathive.co.uk\/nl\/wp-json\/wp\/v2\/types\/page"}],"replies":[{"embeddable":true,"href":"https:\/\/www.cathive.co.uk\/nl\/wp-json\/wp\/v2\/comments?post=26785"}],"version-history":[{"count":1,"href":"https:\/\/www.cathive.co.uk\/nl\/wp-json\/wp\/v2\/pages\/26785\/revisions"}],"predecessor-version":[{"id":26926,"href":"https:\/\/www.cathive.co.uk\/nl\/wp-json\/wp\/v2\/pages\/26785\/revisions\/26926"}],"up":[{"embeddable":true,"href":"https:\/\/www.cathive.co.uk\/nl\/wp-json\/wp\/v2\/pages\/26778"}],"wp:attachment":[{"href":"https:\/\/www.cathive.co.uk\/nl\/wp-json\/wp\/v2\/media?parent=26785"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}