{"id":909,"date":"2026-03-21T14:27:24","date_gmt":"2026-03-21T18:27:24","guid":{"rendered":"https:\/\/www.4roadservice.com\/resources\/?page_id=909"},"modified":"2026-03-21T14:27:28","modified_gmt":"2026-03-21T18:27:28","slug":"detroit-diesel-spn-3480-fmi-16-dpf-ash-load-high","status":"publish","type":"page","link":"https:\/\/www.4roadservice.com\/resources\/detroit-diesel-spn-3480-fmi-16-dpf-ash-load-high\/","title":{"rendered":"Detroit Diesel SPN 3480 FMI 16 \u2013 DPF Ash Load High (Meaning, Causes &amp; Fix)"},"content":{"rendered":"\n<p class=\"wp-block-paragraph\"><a href=\"https:\/\/www.4roadservice.com\/resources\/detroit-diesel-fault-codes-dd13-dd15-dd16\/\">\u2190 Back to Detroit Diesel Fault Codes<\/a><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Detroit Diesel SPN 3480 FMI 16 indicates that the ash load inside the Diesel Particulate Filter has accumulated beyond the acceptable threshold. Unlike soot, ash is a non-combustible byproduct of engine oil consumption and cannot be removed through regeneration. This code appears on DD13, DD15, and DD16 engines and typically means the DPF requires professional cleaning or replacement.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Symptoms<\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Check engine light on <\/li>\n\n\n\n<li>DPF warning light illuminated <\/li>\n\n\n\n<li>Reduced engine performance <\/li>\n\n\n\n<li>Increased exhaust back pressure <\/li>\n\n\n\n<li>Regeneration cycles becoming more frequent <\/li>\n\n\n\n<li>Engine derate possible Regen completing but codes returning quickly<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">Cause<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">This code triggers when the ECM calculates that ash accumulation inside the DPF has exceeded the acceptable level based on engine hours and oil consumption data. Common causes include:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Normal long term ash accumulation over high mileage <\/li>\n\n\n\n<li>Excessive engine oil consumption accelerating ash buildup <\/li>\n\n\n\n<li>Wrong engine oil specification causing higher ash content <\/li>\n\n\n\n<li>Worn piston rings or valve seals increasing oil burning <\/li>\n\n\n\n<li>Extended oil change intervals contributing to higher ash deposits <\/li>\n\n\n\n<li>DPF approaching end of service life<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">Can You Keep Driving?<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Limited driving may be possible but ash cannot be burned off through regeneration like soot can. The DPF will continue to restrict exhaust flow as ash builds up, leading to increased back pressure, more frequent regens, and eventual derate. The DPF needs to be cleaned or replaced to resolve this condition.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Recommended Action<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Have the DPF removed and professionally cleaned using a DPF cleaning machine to remove ash deposits. If the filter is too heavily loaded or damaged it will need to be replaced. Also investigate engine oil consumption \u2014 if the engine is burning excessive oil the root cause should be addressed to prevent rapid ash reaccumulation after cleaning.<\/p>\n\n\n\n<div class=\"schema-faq wp-block-yoast-faq-block\"><div class=\"schema-faq-section\" id=\"faq-question-1774117364531\"><strong class=\"schema-faq-question\">What does Detroit Diesel SPN 3480 FMI 16 mean?<\/strong> <p class=\"schema-faq-answer\">It means the DPF has accumulated too much ash, which is a non-combustible byproduct of oil combustion that cannot be removed through normal regeneration and requires professional cleaning or filter replacement.<\/p> <\/div> <div class=\"schema-faq-section\" id=\"faq-question-1774117366624\"><strong class=\"schema-faq-question\">What causes SPN 3480 FMI 16?<\/strong> <p class=\"schema-faq-answer\">The most common cause is normal long term ash accumulation over high mileage. Excessive engine oil consumption, wrong oil specification, or worn piston rings can accelerate ash buildup significantly.<\/p> <\/div> <div class=\"schema-faq-section\" id=\"faq-question-1774117366231\"><strong class=\"schema-faq-question\">Can I keep driving with SPN 3480 FMI 16?<\/strong> <p class=\"schema-faq-answer\">Short distances may be possible but ash accumulation will not improve on its own. Continued operation will lead to increased back pressure, more frequent regeneration cycles, and eventual derate.<\/p> <\/div> <div class=\"schema-faq-section\" id=\"faq-question-1774117365879\"><strong class=\"schema-faq-question\"><strong>Will SPN 3480 FMI 16 cause a derate?<\/strong><\/strong> <p class=\"schema-faq-answer\">Yes. As ash continues to restrict exhaust flow through the DPF the ECM will trigger derate conditions due to excessive back pressure and reduced aftertreatment performance.<\/p> <\/div> <div class=\"schema-faq-section\" id=\"faq-question-1774117365432\"><strong class=\"schema-faq-question\">How do I clear SPN 3480 FMI 16?<\/strong> <p class=\"schema-faq-answer\">The DPF must be removed and professionally cleaned or replaced. Simply performing a regeneration will not remove ash. Once the cleaned or new filter is reinstalled and the ECM confirms acceptable ash and back pressure levels the code should clear.<\/p> <\/div> <\/div>\n\n\n\n<h2 class=\"wp-block-heading\">Related codes<\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li><a href=\"https:\/\/www.4roadservice.com\/resources\/detroit-diesel-spn-3713-fmi-16-dpf-soot-load-high\/\" type=\"link\" id=\"https:\/\/www.4roadservice.com\/resources\/detroit-diesel-spn-3713-fmi-16-dpf-soot-load-high\/\">SPN 3713 FMI 16 <\/a><\/li>\n\n\n\n<li><a href=\"https:\/\/www.4roadservice.com\/resources\/detroit-diesel-spn-3713-fmi-18-dpf-soot-load-critical\/\" type=\"link\" id=\"https:\/\/www.4roadservice.com\/resources\/detroit-diesel-spn-3713-fmi-18-dpf-soot-load-critical\/\">SPN 3713 FMI 18 <\/a><\/li>\n\n\n\n<li><a href=\"https:\/\/www.4roadservice.com\/resources\/detroit-diesel-spn-3719-fmi-0\/\" type=\"link\" id=\"https:\/\/www.4roadservice.com\/resources\/detroit-diesel-spn-3719-fmi-0\/\">SPN 3719 FMI 0 <\/a><\/li>\n\n\n\n<li><a href=\"https:\/\/www.4roadservice.com\/resources\/detroit-diesel-spn-3251-fmi-18-dpf-differential-pressure-sensor-fault\/\" type=\"link\" id=\"https:\/\/www.4roadservice.com\/resources\/detroit-diesel-spn-3251-fmi-18-dpf-differential-pressure-sensor-fault\/\">SPN 3251 FMI 18 <\/a><\/li>\n\n\n\n<li><a href=\"https:\/\/www.4roadservice.com\/resources\/detroit-diesel-spn-5246-fmi-0\/\" type=\"link\" id=\"https:\/\/www.4roadservice.com\/resources\/detroit-diesel-spn-5246-fmi-0\/\">SPN 5246 FMI 0<\/a><\/li>\n<\/ul>\n\n\n\n<div class=\"wp-block-group\"><div class=\"wp-block-group__inner-container is-layout-constrained wp-block-group-is-layout-constrained\">\n<h2 class=\"wp-block-heading\">Need Immediate Help With This Fault Code?<\/h2>\n<\/div><\/div>\n\n\n\n<p class=\"wp-block-paragraph\">If your engine is derating, losing power, or unable to complete regeneration, don\u2019t risk further damage or costly downtime.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Use 4RoadService to locate mobile truck repair, dealer diagnostics, or emergency roadside assistance near your location.<\/p>\n\n\n\n<div class=\"wp-block-buttons has-off-white-background-color has-background is-content-justification-center is-layout-flex wp-container-core-buttons-is-layout-fe48e5de wp-block-buttons-is-layout-flex\">\n<div class=\"wp-block-button\"><a class=\"wp-block-button__link wp-element-button\" href=\"https:\/\/www.4roadservice.com\/truck-dealers\">Find Truck Repair Near Me<\/a><\/div>\n\n\n\n<div class=\"wp-block-button\"><a class=\"wp-block-button__link has-text-align-center wp-element-button\" href=\"https:\/\/www.4roadservice.com\/truck-repair\">Find Mobile Road Service<\/a><\/div>\n<\/div>\n\n\n\n<h3 class=\"wp-block-heading\">Important Notice<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">The information provided above is for general informational purposes only and should not replace official OEM service procedures. Always consult the manufacturer\u2019s service manual or a qualified diesel technician before performing repairs. Operating a vehicle with active fault codes may result in further damage.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u2190 Back to Detroit Diesel Fault Codes Detroit Diesel SPN 3480 FMI 16 indicates that the ash load inside the Diesel Particulate Filter has accumulated beyond the acceptable threshold. Unlike soot, ash is a non-combustible byproduct of engine oil consumption and cannot be removed through regeneration. This code appears on DD13, DD15, and DD16 engines &hellip; <a href=\"https:\/\/www.4roadservice.com\/resources\/detroit-diesel-spn-3480-fmi-16-dpf-ash-load-high\/\" class=\"more-link\">Continue reading <span class=\"screen-reader-text\">Detroit Diesel SPN 3480 FMI 16 \u2013 DPF Ash Load High (Meaning, Causes &amp; Fix)<\/span> <span class=\"meta-nav\">&rarr;<\/span><\/a><\/p>\n","protected":false},"author":4,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-909","page","type-page","status-publish","hentry"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v28.1 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>SPN 3480 FMI 16 - DPF Ash Load High<\/title>\n<meta name=\"description\" content=\"Detroit Diesel SPN 3480 FMI 16 means DPF ash load is too high. 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Excessive engine oil consumption, wrong oil specification, or worn piston rings can accelerate ash buildup significantly.","inLanguage":"en-US"},"inLanguage":"en-US"},{"@type":"Question","@id":"https:\/\/www.4roadservice.com\/resources\/detroit-diesel-spn-3480-fmi-16-dpf-ash-load-high\/#faq-question-1774117366231","position":3,"url":"https:\/\/www.4roadservice.com\/resources\/detroit-diesel-spn-3480-fmi-16-dpf-ash-load-high\/#faq-question-1774117366231","name":"Can I keep driving with SPN 3480 FMI 16?","answerCount":1,"acceptedAnswer":{"@type":"Answer","text":"Short distances may be possible but ash accumulation will not improve on its own. Continued operation will lead to increased back pressure, more frequent regeneration cycles, and eventual derate.","inLanguage":"en-US"},"inLanguage":"en-US"},{"@type":"Question","@id":"https:\/\/www.4roadservice.com\/resources\/detroit-diesel-spn-3480-fmi-16-dpf-ash-load-high\/#faq-question-1774117365879","position":4,"url":"https:\/\/www.4roadservice.com\/resources\/detroit-diesel-spn-3480-fmi-16-dpf-ash-load-high\/#faq-question-1774117365879","name":"Will SPN 3480 FMI 16 cause a derate?","answerCount":1,"acceptedAnswer":{"@type":"Answer","text":"Yes. As ash continues to restrict exhaust flow through the DPF the ECM will trigger derate conditions due to excessive back pressure and reduced aftertreatment performance.","inLanguage":"en-US"},"inLanguage":"en-US"},{"@type":"Question","@id":"https:\/\/www.4roadservice.com\/resources\/detroit-diesel-spn-3480-fmi-16-dpf-ash-load-high\/#faq-question-1774117365432","position":5,"url":"https:\/\/www.4roadservice.com\/resources\/detroit-diesel-spn-3480-fmi-16-dpf-ash-load-high\/#faq-question-1774117365432","name":"How do I clear SPN 3480 FMI 16?","answerCount":1,"acceptedAnswer":{"@type":"Answer","text":"The DPF must be removed and professionally cleaned or replaced. Simply performing a regeneration will not remove ash. Once the cleaned or new filter is reinstalled and the ECM confirms acceptable ash and back pressure levels the code should clear.","inLanguage":"en-US"},"inLanguage":"en-US"}]}},"jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/P6wicq-eF","_links":{"self":[{"href":"https:\/\/www.4roadservice.com\/resources\/wp-json\/wp\/v2\/pages\/909","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.4roadservice.com\/resources\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/www.4roadservice.com\/resources\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/www.4roadservice.com\/resources\/wp-json\/wp\/v2\/users\/4"}],"replies":[{"embeddable":true,"href":"https:\/\/www.4roadservice.com\/resources\/wp-json\/wp\/v2\/comments?post=909"}],"version-history":[{"count":5,"href":"https:\/\/www.4roadservice.com\/resources\/wp-json\/wp\/v2\/pages\/909\/revisions"}],"predecessor-version":[{"id":915,"href":"https:\/\/www.4roadservice.com\/resources\/wp-json\/wp\/v2\/pages\/909\/revisions\/915"}],"wp:attachment":[{"href":"https:\/\/www.4roadservice.com\/resources\/wp-json\/wp\/v2\/media?parent=909"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}