{"id":976,"date":"2026-04-12T14:38:26","date_gmt":"2026-04-12T18:38:26","guid":{"rendered":"https:\/\/www.4roadservice.com\/resources\/?page_id=976"},"modified":"2026-04-12T14:38:29","modified_gmt":"2026-04-12T18:38:29","slug":"detroit-diesel-spn-3700-fmi-1-dpf-outlet-temperature-low","status":"publish","type":"page","link":"https:\/\/www.4roadservice.com\/resources\/detroit-diesel-spn-3700-fmi-1-dpf-outlet-temperature-low\/","title":{"rendered":"SPN 3700 FMI 1 \u2013 DPF Outlet Temperature Low"},"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 3700 FMI 1 indicates that the temperature at the DPF outlet is below the minimum acceptable threshold. This code appears on DD13, DD15, and DD16 engines and signals that exhaust temperatures exiting the DPF are insufficient for proper aftertreatment operation. Low outlet temperatures can prevent effective regeneration and indicate issues with exhaust heat management or sensor accuracy.<\/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 or regen warning light illuminated <\/li>\n\n\n\n<li>Passive regeneration unable to complete effectively <\/li>\n\n\n\n<li>DPF soot load gradually increasing <\/li>\n\n\n\n<li>Reduced aftertreatment efficiency <\/li>\n\n\n\n<li>May appear alongside DPF inlet temperature low codes<\/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 DPF outlet temperature sensor detects exhaust temperatures below the minimum required threshold after passing through the filter. Common causes include:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Extended idling or light load operation preventing adequate exhaust temperatures <\/li>\n\n\n\n<li>Frequent short trips not allowing engine to reach full operating temperature <\/li>\n\n\n\n<li>Faulty or stuck open thermostat causing low engine and exhaust temperatures <\/li>\n\n\n\n<li>Failed DPF outlet temperature sensor giving false low readings <\/li>\n\n\n\n<li>Damaged or missing exhaust insulation causing excessive heat loss <\/li>\n\n\n\n<li>Engine running lean or misfiring reducing exhaust output temperatures <\/li>\n\n\n\n<li>Cold weather operation with light duty cycles<\/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\">Driving is possible but low DPF outlet temperatures indicate the aftertreatment system is not reaching the temperatures needed for effective regeneration. Soot will accumulate over time leading to more severe DPF faults if the root cause is not addressed.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Recommended Action<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Check engine operating temperature and thermostat condition. Review the vehicle duty cycle for excessive idling or short trip patterns. Inspect the DPF outlet temperature sensor and wiring for damage or corrosion. Check exhaust insulation for damage that may be causing excessive heat loss between the DPF inlet and outlet.<\/p>\n\n\n\n<div class=\"schema-faq wp-block-yoast-faq-block\"><div class=\"schema-faq-section\" id=\"faq-question-1776018478547\"><strong class=\"schema-faq-question\">What does Detroit Diesel SPN 3700 FMI 1 mean?<\/strong> <p class=\"schema-faq-answer\">It means the temperature exiting the DPF is below the minimum required threshold, indicating exhaust heat is insufficient for effective aftertreatment operation and regeneration.<\/p> <\/div> <div class=\"schema-faq-section\" id=\"faq-question-1776018808101\"><strong class=\"schema-faq-question\">What causes SPN 3700 FMI 1?<\/strong> <p class=\"schema-faq-answer\">The most common causes are extended idling, frequent short trips, a faulty thermostat causing low engine temperatures, a failed DPF outlet temperature sensor, or damaged exhaust insulation.<\/p> <\/div> <div class=\"schema-faq-section\" id=\"faq-question-1776018480459\"><strong class=\"schema-faq-question\">Can I keep driving with SPN 3700 FMI 1?<\/strong> <p class=\"schema-faq-answer\">Driving is possible but ongoing low outlet temperatures will prevent effective regeneration and allow soot to accumulate leading to more severe DPF faults over time.<\/p> <\/div> <div class=\"schema-faq-section\" id=\"faq-question-1776018480179\"><strong class=\"schema-faq-question\">Will SPN 3700 FMI 1 cause a derate?<\/strong> <p class=\"schema-faq-answer\">Not immediately but soot accumulation resulting from ineffective regeneration will eventually trigger DPF soot load codes and derate conditions.<\/p> <\/div> <div class=\"schema-faq-section\" id=\"faq-question-1776018479930\"><strong class=\"schema-faq-question\">How do I clear SPN 3700 FMI 1?<\/strong> <p class=\"schema-faq-answer\">Address the root cause of low exhaust temperatures \u2014 check the thermostat, duty cycle, and temperature sensor. Once DPF outlet temperatures return to the normal operating range the code should clear.<\/p> <\/div> <div class=\"schema-faq-section\" id=\"faq-question-1776018479627\"><strong class=\"schema-faq-question\"><\/strong> <p class=\"schema-faq-answer\"><\/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-3700-fmi-16-dpf-outlet-temperature-high\/\" type=\"link\" id=\"https:\/\/www.4roadservice.com\/resources\/detroit-diesel-spn-3700-fmi-16-dpf-outlet-temperature-high\/\">SPN 3700 FMI 16 <\/a><\/li>\n\n\n\n<li><a href=\"https:\/\/www.4roadservice.com\/resources\/detroit-diesel-spn-3242-fmi-1-dpf-inlet-temperature-low\/\" type=\"link\" id=\"https:\/\/www.4roadservice.com\/resources\/detroit-diesel-spn-3242-fmi-1-dpf-inlet-temperature-low\/\">SPN 3242 FMI 1 <\/a><\/li>\n\n\n\n<li><a href=\"https:\/\/www.4roadservice.com\/resources\/detroit-diesel-spn-3242-fmi-16-dpf-inlet-temperature-high-meaning-causes-fix\/\" type=\"link\" id=\"https:\/\/www.4roadservice.com\/resources\/detroit-diesel-spn-3242-fmi-16-dpf-inlet-temperature-high-meaning-causes-fix\/\">SPN 3242 FMI 16 <\/a><\/li>\n\n\n\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-3826-fmi-16-dpf-incomplete-regeneration\/\" type=\"link\" id=\"https:\/\/www.4roadservice.com\/resources\/detroit-diesel-spn-3826-fmi-16-dpf-incomplete-regeneration\/\">SPN 3826 FMI 16<\/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 3700 FMI 1 indicates that the temperature at the DPF outlet is below the minimum acceptable threshold. This code appears on DD13, DD15, and DD16 engines and signals that exhaust temperatures exiting the DPF are insufficient for proper aftertreatment operation. Low outlet temperatures can prevent &hellip; <a href=\"https:\/\/www.4roadservice.com\/resources\/detroit-diesel-spn-3700-fmi-1-dpf-outlet-temperature-low\/\" class=\"more-link\">Continue reading <span class=\"screen-reader-text\">SPN 3700 FMI 1 \u2013 DPF Outlet Temperature Low<\/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-976","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>Detroit Diesel SPN 3700 FMI 1 \u2013 DPF Outlet Temperature Low<\/title>\n<meta name=\"description\" content=\"Detroit Diesel SPN 3700 FMI 1 means DPF outlet temperature is too low. 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Resources for Truck Drivers","publisher":{"@id":"https:\/\/www.4roadservice.com\/resources\/#organization"},"potentialAction":[{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https:\/\/www.4roadservice.com\/resources\/?s={search_term_string}"},"query-input":{"@type":"PropertyValueSpecification","valueRequired":true,"valueName":"search_term_string"}}],"inLanguage":"en-US"},{"@type":"Organization","@id":"https:\/\/www.4roadservice.com\/resources\/#organization","name":"4RoadService.com","url":"https:\/\/www.4roadservice.com\/resources\/","logo":{"@type":"ImageObject","inLanguage":"en-US","@id":"https:\/\/www.4roadservice.com\/resources\/#\/schema\/logo\/image\/","url":"https:\/\/blog.4roadservice.com\/wp-content\/uploads\/2015\/08\/logo-sidebar@2x.png","contentUrl":"https:\/\/blog.4roadservice.com\/wp-content\/uploads\/2015\/08\/logo-sidebar@2x.png","width":380,"height":64,"caption":"4RoadService.com"},"image":{"@id":"https:\/\/www.4roadservice.com\/resources\/#\/schema\/logo\/image\/"},"sameAs":["https:\/\/www.facebook.com\/4roadservice","https:\/\/x.com\/4RoadService"]},{"@type":"Question","@id":"https:\/\/www.4roadservice.com\/resources\/detroit-diesel-spn-3700-fmi-1-dpf-outlet-temperature-low\/#faq-question-1776018478547","position":1,"url":"https:\/\/www.4roadservice.com\/resources\/detroit-diesel-spn-3700-fmi-1-dpf-outlet-temperature-low\/#faq-question-1776018478547","name":"What does Detroit Diesel SPN 3700 FMI 1 mean?","answerCount":1,"acceptedAnswer":{"@type":"Answer","text":"It means the temperature exiting the DPF is below the minimum required threshold, indicating exhaust heat is insufficient for effective aftertreatment operation and regeneration.","inLanguage":"en-US"},"inLanguage":"en-US"},{"@type":"Question","@id":"https:\/\/www.4roadservice.com\/resources\/detroit-diesel-spn-3700-fmi-1-dpf-outlet-temperature-low\/#faq-question-1776018808101","position":2,"url":"https:\/\/www.4roadservice.com\/resources\/detroit-diesel-spn-3700-fmi-1-dpf-outlet-temperature-low\/#faq-question-1776018808101","name":"What causes SPN 3700 FMI 1?","answerCount":1,"acceptedAnswer":{"@type":"Answer","text":"The most common causes are extended idling, frequent short trips, a faulty thermostat causing low engine temperatures, a failed DPF outlet temperature sensor, or damaged exhaust insulation.","inLanguage":"en-US"},"inLanguage":"en-US"},{"@type":"Question","@id":"https:\/\/www.4roadservice.com\/resources\/detroit-diesel-spn-3700-fmi-1-dpf-outlet-temperature-low\/#faq-question-1776018480459","position":3,"url":"https:\/\/www.4roadservice.com\/resources\/detroit-diesel-spn-3700-fmi-1-dpf-outlet-temperature-low\/#faq-question-1776018480459","name":"Can I keep driving with SPN 3700 FMI 1?","answerCount":1,"acceptedAnswer":{"@type":"Answer","text":"Driving is possible but ongoing low outlet temperatures will prevent effective regeneration and allow soot to accumulate leading to more severe DPF faults over time.","inLanguage":"en-US"},"inLanguage":"en-US"},{"@type":"Question","@id":"https:\/\/www.4roadservice.com\/resources\/detroit-diesel-spn-3700-fmi-1-dpf-outlet-temperature-low\/#faq-question-1776018480179","position":4,"url":"https:\/\/www.4roadservice.com\/resources\/detroit-diesel-spn-3700-fmi-1-dpf-outlet-temperature-low\/#faq-question-1776018480179","name":"Will SPN 3700 FMI 1 cause a derate?","answerCount":1,"acceptedAnswer":{"@type":"Answer","text":"Not immediately but soot accumulation resulting from ineffective regeneration will eventually trigger DPF soot load codes and derate conditions.","inLanguage":"en-US"},"inLanguage":"en-US"},{"@type":"Question","@id":"https:\/\/www.4roadservice.com\/resources\/detroit-diesel-spn-3700-fmi-1-dpf-outlet-temperature-low\/#faq-question-1776018479930","position":5,"url":"https:\/\/www.4roadservice.com\/resources\/detroit-diesel-spn-3700-fmi-1-dpf-outlet-temperature-low\/#faq-question-1776018479930","name":"How do I clear SPN 3700 FMI 1?","answerCount":1,"acceptedAnswer":{"@type":"Answer","text":"Address the root cause of low exhaust temperatures \u2014 check the thermostat, duty cycle, and temperature sensor. Once DPF outlet temperatures return to the normal operating range the code should clear.","inLanguage":"en-US"},"inLanguage":"en-US"}]}},"jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/P6wicq-fK","_links":{"self":[{"href":"https:\/\/www.4roadservice.com\/resources\/wp-json\/wp\/v2\/pages\/976","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=976"}],"version-history":[{"count":4,"href":"https:\/\/www.4roadservice.com\/resources\/wp-json\/wp\/v2\/pages\/976\/revisions"}],"predecessor-version":[{"id":981,"href":"https:\/\/www.4roadservice.com\/resources\/wp-json\/wp\/v2\/pages\/976\/revisions\/981"}],"wp:attachment":[{"href":"https:\/\/www.4roadservice.com\/resources\/wp-json\/wp\/v2\/media?parent=976"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}