{"id":1385,"date":"2025-09-29T08:19:19","date_gmt":"2025-09-29T08:19:19","guid":{"rendered":"https:\/\/www.way.com\/ask\/?p=1385"},"modified":"2025-09-29T08:19:19","modified_gmt":"2025-09-29T08:19:19","slug":"how-to-diagnose-and-fix-a-p0420-code-on-a-subaru","status":"publish","type":"post","link":"https:\/\/www.way.com\/ask\/how-to-diagnose-and-fix-a-p0420-code-on-a-subaru\/","title":{"rendered":"How to diagnose and fix a P0420 code on a Subaru?\u00a0"},"content":{"rendered":"<ul>\n<li><span data-contrast=\"none\">Inspect the catalytic converter for any damage or contamination. Perform a pressure test to determine whether it&#8217;s functioning properly<\/span><span data-ccp-props=\"{}\">\u00a0<\/span><\/li>\n<li><span data-contrast=\"none\">Check whether the oxygen sensors are giving accurate readings. A malfunctioning 02 sensor can also cause a P0420 on a Subaru<\/span><span data-ccp-props=\"{}\">\u00a0<\/span><\/li>\n<li><span data-contrast=\"none\">Check the exhaust system for any leaks, damage or corrosion<\/span><span data-ccp-props=\"{}\">\u00a0<\/span><\/li>\n<li><span data-contrast=\"none\">The fuel system should be thoroughly investigated. Ensure that the fuel injectors are working properly\u00a0and the fuel filter is unclogged. <\/span><span data-ccp-props=\"{}\">\u00a0<\/span><\/li>\n<li><span data-contrast=\"none\">Inspect the EGR system<\/span><span data-ccp-props=\"{}\">\u00a0<\/span><\/li>\n<li><span data-contrast=\"none\">While you are at it, get your catalytic converter cleaned<\/span><span data-ccp-props=\"{}\">\u00a0<\/span><\/li>\n<\/ul>\n<p><span data-contrast=\"none\">Diagnosing a P0420 on a Subaru accurately is half the battle won and fixing it is comparatively easier. Here\u2019s what you\u2019ll need to do:<\/span><span data-ccp-props=\"{&quot;335559685&quot;:0}\">\u00a0<\/span><\/p>\n<ul>\n<li><span data-contrast=\"none\">Locate and repair any exhaust leaks<\/span><span data-ccp-props=\"{}\">\u00a0<\/span><\/li>\n<li><span data-contrast=\"none\">Replace any faulty sensors<\/span><span data-ccp-props=\"{}\">\u00a0<\/span><\/li>\n<li><span data-contrast=\"none\">Replace spark plugs, spark plug wires, and the air filter to ensure the engine is running efficiently. An efficiently running engine means a functioning catalytic converter.<\/span><span data-ccp-props=\"{}\">\u00a0<\/span><\/li>\n<li><span data-contrast=\"none\">If the problem persists, it\u2019s probably time to replace your catalytic converter.\u00a0Make sure to use original equipment manufacturer parts and not the aftermarket ones.<\/span><span data-ccp-props=\"{&quot;134233117&quot;:false,&quot;134233118&quot;:false,&quot;335551550&quot;:0,&quot;335551620&quot;:0,&quot;335557856&quot;:16777215,&quot;335559738&quot;:240,&quot;335559739&quot;:240}\">\u00a0<\/span><\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"<p>Inspect the catalytic converter for any damage or contamination. Perform a pressure test to determine whether it&#8217;s functioning properly\u00a0 Check whether the oxygen sensors are giving accurate readings. A malfunctioning 02 sensor can also cause a P0420 on a Subaru\u00a0 Check the exhaust system for any leaks, damage or corrosion\u00a0 The fuel system should be&hellip; <a class=\"more-link\" href=\"https:\/\/www.way.com\/ask\/how-to-diagnose-and-fix-a-p0420-code-on-a-subaru\/\">Continue reading <span class=\"screen-reader-text\">How to diagnose and fix a P0420 code on a Subaru?\u00a0<\/span><\/a><\/p>\n","protected":false},"author":11,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[1],"tags":[],"class_list":["post-1385","post","type-post","status-publish","format-standard","hentry","category-car-repair-maintenance","entry"],"acf":[],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v27.1.1 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>How to diagnose and fix a P0420 code on a Subaru?\u00a0 - ask<\/title>\n<meta name=\"description\" content=\"Want to know how to diagnose and fix a P0420 code on a Subaru?\u00a0Well, here&#039;s everything you need to know and more.\" \/>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.way.com\/ask\/how-to-diagnose-and-fix-a-p0420-code-on-a-subaru\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"How to diagnose and fix a P0420 code on a Subaru?\u00a0 - ask\" \/>\n<meta property=\"og:description\" content=\"Want to know how to diagnose and fix a P0420 code on a Subaru?\u00a0Well, here&#039;s everything you need to know and more.\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.way.com\/ask\/how-to-diagnose-and-fix-a-p0420-code-on-a-subaru\/\" \/>\n<meta property=\"og:site_name\" content=\"ask\" \/>\n<meta property=\"article:published_time\" content=\"2025-09-29T08:19:19+00:00\" \/>\n<meta name=\"author\" content=\"Gareth Newman\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:label1\" content=\"Written by\" \/>\n\t<meta name=\"twitter:data1\" content=\"Gareth Newman\" \/>\n\t<meta name=\"twitter:label2\" content=\"Est. reading time\" \/>\n\t<meta name=\"twitter:data2\" content=\"1 minute\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\/\/schema.org\",\"@graph\":[{\"@type\":\"Article\",\"@id\":\"https:\/\/www.way.com\/ask\/how-to-diagnose-and-fix-a-p0420-code-on-a-subaru\/#article\",\"isPartOf\":{\"@id\":\"https:\/\/www.way.com\/ask\/how-to-diagnose-and-fix-a-p0420-code-on-a-subaru\/\"},\"author\":{\"name\":\"Gareth Newman\",\"@id\":\"https:\/\/www.way.com\/ask\/#\/schema\/person\/418ef9e86ed6bfcb5b45b3cdac1ab9c9\"},\"headline\":\"How to diagnose and fix a P0420 code on a Subaru?\u00a0\",\"datePublished\":\"2025-09-29T08:19:19+00:00\",\"mainEntityOfPage\":{\"@id\":\"https:\/\/www.way.com\/ask\/how-to-diagnose-and-fix-a-p0420-code-on-a-subaru\/\"},\"wordCount\":183,\"commentCount\":0,\"publisher\":{\"@id\":\"https:\/\/www.way.com\/ask\/#organization\"},\"articleSection\":[\"Car Repair &amp; Maintenance\"],\"inLanguage\":\"en-US\",\"potentialAction\":[{\"@type\":\"CommentAction\",\"name\":\"Comment\",\"target\":[\"https:\/\/www.way.com\/ask\/how-to-diagnose-and-fix-a-p0420-code-on-a-subaru\/#respond\"]}]},{\"@type\":\"WebPage\",\"@id\":\"https:\/\/www.way.com\/ask\/how-to-diagnose-and-fix-a-p0420-code-on-a-subaru\/\",\"url\":\"https:\/\/www.way.com\/ask\/how-to-diagnose-and-fix-a-p0420-code-on-a-subaru\/\",\"name\":\"How to diagnose and fix a P0420 code on a Subaru?\u00a0 - ask\",\"isPartOf\":{\"@id\":\"https:\/\/www.way.com\/ask\/#website\"},\"datePublished\":\"2025-09-29T08:19:19+00:00\",\"description\":\"Want to know how to diagnose and fix a P0420 code on a Subaru?\u00a0Well, here's everything you need to know and more.\",\"breadcrumb\":{\"@id\":\"https:\/\/www.way.com\/ask\/how-to-diagnose-and-fix-a-p0420-code-on-a-subaru\/#breadcrumb\"},\"inLanguage\":\"en-US\",\"potentialAction\":[{\"@type\":\"ReadAction\",\"target\":[\"https:\/\/www.way.com\/ask\/how-to-diagnose-and-fix-a-p0420-code-on-a-subaru\/\"]}]},{\"@type\":\"BreadcrumbList\",\"@id\":\"https:\/\/www.way.com\/ask\/how-to-diagnose-and-fix-a-p0420-code-on-a-subaru\/#breadcrumb\",\"itemListElement\":[{\"@type\":\"ListItem\",\"position\":1,\"name\":\"Home\",\"item\":\"https:\/\/www.way.com\/ask\/\"},{\"@type\":\"ListItem\",\"position\":2,\"name\":\"How to diagnose and fix a P0420 code on a Subaru?\u00a0\"}]},{\"@type\":\"WebSite\",\"@id\":\"https:\/\/www.way.com\/ask\/#website\",\"url\":\"https:\/\/www.way.com\/ask\/\",\"name\":\"ask\",\"description\":\"\",\"publisher\":{\"@id\":\"https:\/\/www.way.com\/ask\/#organization\"},\"potentialAction\":[{\"@type\":\"SearchAction\",\"target\":{\"@type\":\"EntryPoint\",\"urlTemplate\":\"https:\/\/www.way.com\/ask\/?s={search_term_string}\"},\"query-input\":{\"@type\":\"PropertyValueSpecification\",\"valueRequired\":true,\"valueName\":\"search_term_string\"}}],\"inLanguage\":\"en-US\"},{\"@type\":\"Organization\",\"@id\":\"https:\/\/www.way.com\/ask\/#organization\",\"name\":\"ask\",\"url\":\"https:\/\/www.way.com\/ask\/\",\"logo\":{\"@type\":\"ImageObject\",\"inLanguage\":\"en-US\",\"@id\":\"https:\/\/www.way.com\/ask\/#\/schema\/logo\/image\/\",\"url\":\"https:\/\/www.way.com\/ask\/wp-content\/uploads\/2024\/11\/logo-text.png\",\"contentUrl\":\"https:\/\/www.way.com\/ask\/wp-content\/uploads\/2024\/11\/logo-text.png\",\"width\":96,\"height\":37,\"caption\":\"ask\"},\"image\":{\"@id\":\"https:\/\/www.way.com\/ask\/#\/schema\/logo\/image\/\"}},{\"@type\":\"Person\",\"@id\":\"https:\/\/www.way.com\/ask\/#\/schema\/person\/418ef9e86ed6bfcb5b45b3cdac1ab9c9\",\"name\":\"Gareth Newman\",\"image\":{\"@type\":\"ImageObject\",\"inLanguage\":\"en-US\",\"@id\":\"https:\/\/www.way.com\/ask\/#\/schema\/person\/image\/\",\"url\":\"https:\/\/secure.gravatar.com\/avatar\/9475312dfad46f7dabc15241d0f0be990aa26fb0202c2d0e2e470dc4834ff123?s=96&d=mm&r=g\",\"contentUrl\":\"https:\/\/secure.gravatar.com\/avatar\/9475312dfad46f7dabc15241d0f0be990aa26fb0202c2d0e2e470dc4834ff123?s=96&d=mm&r=g\",\"caption\":\"Gareth Newman\"},\"url\":\"https:\/\/www.way.com\/ask\/author\/gareth-newman\/\"}]}<\/script>\n<!-- \/ Yoast SEO plugin. -->","yoast_head_json":{"title":"How to diagnose and fix a P0420 code on a Subaru?\u00a0 - ask","description":"Want to know how to diagnose and fix a P0420 code on a Subaru?\u00a0Well, here's everything you need to know and more.","robots":{"index":"index","follow":"follow","max-snippet":"max-snippet:-1","max-image-preview":"max-image-preview:large","max-video-preview":"max-video-preview:-1"},"canonical":"https:\/\/www.way.com\/ask\/how-to-diagnose-and-fix-a-p0420-code-on-a-subaru\/","og_locale":"en_US","og_type":"article","og_title":"How to diagnose and fix a P0420 code on a Subaru?\u00a0 - ask","og_description":"Want to know how to diagnose and fix a P0420 code on a Subaru?\u00a0Well, here's everything you need to know and more.","og_url":"https:\/\/www.way.com\/ask\/how-to-diagnose-and-fix-a-p0420-code-on-a-subaru\/","og_site_name":"ask","article_published_time":"2025-09-29T08:19:19+00:00","author":"Gareth Newman","twitter_card":"summary_large_image","twitter_misc":{"Written by":"Gareth Newman","Est. reading time":"1 minute"},"schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":"Article","@id":"https:\/\/www.way.com\/ask\/how-to-diagnose-and-fix-a-p0420-code-on-a-subaru\/#article","isPartOf":{"@id":"https:\/\/www.way.com\/ask\/how-to-diagnose-and-fix-a-p0420-code-on-a-subaru\/"},"author":{"name":"Gareth Newman","@id":"https:\/\/www.way.com\/ask\/#\/schema\/person\/418ef9e86ed6bfcb5b45b3cdac1ab9c9"},"headline":"How to diagnose and fix a P0420 code on a Subaru?\u00a0","datePublished":"2025-09-29T08:19:19+00:00","mainEntityOfPage":{"@id":"https:\/\/www.way.com\/ask\/how-to-diagnose-and-fix-a-p0420-code-on-a-subaru\/"},"wordCount":183,"commentCount":0,"publisher":{"@id":"https:\/\/www.way.com\/ask\/#organization"},"articleSection":["Car Repair &amp; Maintenance"],"inLanguage":"en-US","potentialAction":[{"@type":"CommentAction","name":"Comment","target":["https:\/\/www.way.com\/ask\/how-to-diagnose-and-fix-a-p0420-code-on-a-subaru\/#respond"]}]},{"@type":"WebPage","@id":"https:\/\/www.way.com\/ask\/how-to-diagnose-and-fix-a-p0420-code-on-a-subaru\/","url":"https:\/\/www.way.com\/ask\/how-to-diagnose-and-fix-a-p0420-code-on-a-subaru\/","name":"How to diagnose and fix a P0420 code on a Subaru?\u00a0 - ask","isPartOf":{"@id":"https:\/\/www.way.com\/ask\/#website"},"datePublished":"2025-09-29T08:19:19+00:00","description":"Want to know how to diagnose and fix a P0420 code on a Subaru?\u00a0Well, here's everything you need to know and more.","breadcrumb":{"@id":"https:\/\/www.way.com\/ask\/how-to-diagnose-and-fix-a-p0420-code-on-a-subaru\/#breadcrumb"},"inLanguage":"en-US","potentialAction":[{"@type":"ReadAction","target":["https:\/\/www.way.com\/ask\/how-to-diagnose-and-fix-a-p0420-code-on-a-subaru\/"]}]},{"@type":"BreadcrumbList","@id":"https:\/\/www.way.com\/ask\/how-to-diagnose-and-fix-a-p0420-code-on-a-subaru\/#breadcrumb","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https:\/\/www.way.com\/ask\/"},{"@type":"ListItem","position":2,"name":"How to diagnose and fix a P0420 code on a Subaru?\u00a0"}]},{"@type":"WebSite","@id":"https:\/\/www.way.com\/ask\/#website","url":"https:\/\/www.way.com\/ask\/","name":"ask","description":"","publisher":{"@id":"https:\/\/www.way.com\/ask\/#organization"},"potentialAction":[{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https:\/\/www.way.com\/ask\/?s={search_term_string}"},"query-input":{"@type":"PropertyValueSpecification","valueRequired":true,"valueName":"search_term_string"}}],"inLanguage":"en-US"},{"@type":"Organization","@id":"https:\/\/www.way.com\/ask\/#organization","name":"ask","url":"https:\/\/www.way.com\/ask\/","logo":{"@type":"ImageObject","inLanguage":"en-US","@id":"https:\/\/www.way.com\/ask\/#\/schema\/logo\/image\/","url":"https:\/\/www.way.com\/ask\/wp-content\/uploads\/2024\/11\/logo-text.png","contentUrl":"https:\/\/www.way.com\/ask\/wp-content\/uploads\/2024\/11\/logo-text.png","width":96,"height":37,"caption":"ask"},"image":{"@id":"https:\/\/www.way.com\/ask\/#\/schema\/logo\/image\/"}},{"@type":"Person","@id":"https:\/\/www.way.com\/ask\/#\/schema\/person\/418ef9e86ed6bfcb5b45b3cdac1ab9c9","name":"Gareth Newman","image":{"@type":"ImageObject","inLanguage":"en-US","@id":"https:\/\/www.way.com\/ask\/#\/schema\/person\/image\/","url":"https:\/\/secure.gravatar.com\/avatar\/9475312dfad46f7dabc15241d0f0be990aa26fb0202c2d0e2e470dc4834ff123?s=96&d=mm&r=g","contentUrl":"https:\/\/secure.gravatar.com\/avatar\/9475312dfad46f7dabc15241d0f0be990aa26fb0202c2d0e2e470dc4834ff123?s=96&d=mm&r=g","caption":"Gareth Newman"},"url":"https:\/\/www.way.com\/ask\/author\/gareth-newman\/"}]}},"_links":{"self":[{"href":"https:\/\/www.way.com\/ask\/wp-json\/wp\/v2\/posts\/1385","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.way.com\/ask\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.way.com\/ask\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.way.com\/ask\/wp-json\/wp\/v2\/users\/11"}],"replies":[{"embeddable":true,"href":"https:\/\/www.way.com\/ask\/wp-json\/wp\/v2\/comments?post=1385"}],"version-history":[{"count":1,"href":"https:\/\/www.way.com\/ask\/wp-json\/wp\/v2\/posts\/1385\/revisions"}],"predecessor-version":[{"id":1386,"href":"https:\/\/www.way.com\/ask\/wp-json\/wp\/v2\/posts\/1385\/revisions\/1386"}],"wp:attachment":[{"href":"https:\/\/www.way.com\/ask\/wp-json\/wp\/v2\/media?parent=1385"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.way.com\/ask\/wp-json\/wp\/v2\/categories?post=1385"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.way.com\/ask\/wp-json\/wp\/v2\/tags?post=1385"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}