{"id":70834,"date":"2022-08-09T23:52:23","date_gmt":"2022-08-10T06:52:23","guid":{"rendered":"https:\/\/blogv2prod.wpenginepowered.com\/blog\/?p=70834"},"modified":"2024-01-24T17:38:43","modified_gmt":"2024-01-25T01:38:43","slug":"u0121-code-lost-communication-with-anti-lock-braking-system-abs-module","status":"publish","type":"post","link":"https:\/\/www.carparts.com\/blog\/u0121-code-lost-communication-with-anti-lock-braking-system-abs-module\/","title":{"rendered":"U0121 Code: Lost Communication With Anti-Lock Braking System (ABS) Module"},"content":{"rendered":"<!DOCTYPE html PUBLIC \"-\/\/W3C\/\/DTD HTML 4.0 Transitional\/\/EN\" \"http:\/\/www.w3.org\/TR\/REC-html40\/loose.dtd\">\n<html><body><span class=\"span-reading-time rt-reading-time\" style=\"display: block;\"><span class=\"rt-label rt-prefix\">Reading Time: <\/span> <span class=\"rt-time\"> 3<\/span> <span class=\"rt-label rt-postfix\">minutes<\/span><\/span><style>.kadence-column_2737b5-cd > .kt-inside-inner-col{border-top-width:0px;border-right-width:0px;border-bottom-width:0px;border-left-width:0px;}.kadence-column_2737b5-cd > .kt-inside-inner-col,.kadence-column_2737b5-cd > .kt-inside-inner-col:before{border-top-left-radius:0px;border-top-right-radius:0px;border-bottom-right-radius:0px;border-bottom-left-radius:0px;}.kadence-column_2737b5-cd > .kt-inside-inner-col{column-gap:var(--global-kb-gap-sm, 1rem);}.kadence-column_2737b5-cd > .kt-inside-inner-col{flex-direction:column;}.kadence-column_2737b5-cd > .kt-inside-inner-col > .aligncenter{width:100%;}.kadence-column_2737b5-cd > .kt-inside-inner-col:before{opacity:0.3;}.kadence-column_2737b5-cd{position:relative;}@media all and (max-width: 1024px){.kadence-column_2737b5-cd > .kt-inside-inner-col{flex-direction:column;justify-content:center;}}@media all and (max-width: 767px){.kadence-column_2737b5-cd > .kt-inside-inner-col{flex-direction:column;justify-content:center;}}<\/style>\n<div class=\"wp-block-kadence-column inner-column-1 kadence-column_2737b5-cd qk-look-widget\"><div class=\"kt-inside-inner-col\">\n<div class=\"wp-block-ultimate-post-row ultp-block-7b0d03  qk-main-wrap\"><div class=\"ultp-row-wrapper\"><div class=\"ultp-row-content\">\n<div class=\"wp-block-ultimate-post-column ultp-block-0680ea\"><div class=\"ultp-column-wrapper\"><style>.wp-block-kadence-advancedheading.kt-adv-heading_9ea5b4-4a, .wp-block-kadence-advancedheading.kt-adv-heading_9ea5b4-4a[data-kb-block=\"kb-adv-heading_9ea5b4-4a\"]{text-align:center;font-size:20px;font-style:normal;}.wp-block-kadence-advancedheading.kt-adv-heading_9ea5b4-4a mark.kt-highlight, .wp-block-kadence-advancedheading.kt-adv-heading_9ea5b4-4a[data-kb-block=\"kb-adv-heading_9ea5b4-4a\"] mark.kt-highlight{font-family:Inter;font-weight:500;font-style:normal;color:#f76a0c;-webkit-box-decoration-break:clone;box-decoration-break:clone;padding-top:0px;padding-right:0px;padding-bottom:0px;padding-left:0px;}.wp-block-kadence-advancedheading.kt-adv-heading_9ea5b4-4a img.kb-inline-image, .wp-block-kadence-advancedheading.kt-adv-heading_9ea5b4-4a[data-kb-block=\"kb-adv-heading_9ea5b4-4a\"] img.kb-inline-image{width:150px;vertical-align:baseline;}<\/style>\n<div class=\"kt-adv-heading_9ea5b4-4a summary-title wp-block-kadence-advancedheading\" data-kb-block=\"kb-adv-heading_9ea5b4-4a\"><span>Summary<\/span><\/div>\n\n\n\n<ul class=\"wp-block-list\"><li>The U0121 code stands for &ldquo;Lost Communication With Anti-Lock Braking System (ABS) Module.&rdquo;<\/li><li>Some issues that could trigger the code include a dead battery, a faulty ABS control module, and CAN bus issues.<\/li><li>It&rsquo;s best to let a professional resolve this code instead of trying to repair it yourself.<\/li><\/ul>\n<\/div><\/div>\n<\/div><\/div><\/div>\n<\/div><\/div>\n\n\n\n\n\n<p>Most modern vehicles are equipped with an <a href=\"https:\/\/www.carparts.com\/blog\/what-is-abs-anti-lock-braking-system-a-complete-guide\/\" target=\"_blank\" rel=\"noreferrer noopener\" aria-label=\"anti-lock braking system\">anti-lock braking system<\/a> (ABS). The system prevents the wheels from locking up during emergency braking situations and whenever the roads are slippery. It also reduces the risk of skidding during a panic stop, which helps the driver maintain vehicle control.<\/p>\n\n\n\n<p>The ABS has a <a href=\"https:\/\/www.carparts.com\/abs-control-module\" target=\"_blank\" rel=\"noreferrer noopener\" aria-label=\"control module\">control module<\/a> that relies on the input from the wheel speed sensors to monitor the wheels&rsquo; deceleration rates during braking. This module also communicates with other on-board computers over the controller area network (CAN) bus to operate the entire ABS.<\/p>\n\n\n\n<p>If the module is unable to receive and transmit information over the CAN bus, fault code U0121 will be logged by on-board diagnostics.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">What Does the U0121 Code Mean?<\/h2>\n\n\n\n<p>Fault code U0121 stands for &ldquo;Lost Communication With Anti-Lock Braking System (ABS) Module.&rdquo;<\/p>\n\n\n\n<p>The ABS module issues the necessary commands to modulate brake pressure and maintain the correct percentage of tire slip under emergency braking and adverse road surface conditions.<\/p>\n\n\n\n<p>If the module detects that wheel lockup is about to take place, it will command the hydraulic modulator to regulate fluid pressure accordingly. The prompt applies until the hydraulic control reaches its final phase, which is referred to as the pressure increase phase. This means that the maximum master cylinder pressure has been applied to the wheels.<\/p>\n\n\n\n<p><strong><em>Note:<\/em><\/strong><em> The definition of code U0121 might be different depending on the vehicle manufacturer. Consult the appropriate repair manual or repair database for the exact code definition.<\/em><\/p>\n\n\n\n<figure class=\"wp-block-image size-large is-resized\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/www.carparts.com\/blog\/wp-content\/uploads\/2022\/07\/automotive-ABS-Control-Module-in-engine-area-focused-1024x682.jpg\" alt=\"automotive ABS Control Module in engine area focused\" class=\"wp-image-70835\" width=\"1024\" height=\"682\" srcset=\"https:\/\/www.carparts.com\/blog\/wp-content\/uploads\/2022\/07\/automotive-ABS-Control-Module-in-engine-area-focused-1024x682.jpg 1024w, https:\/\/www.carparts.com\/blog\/wp-content\/uploads\/2022\/07\/automotive-ABS-Control-Module-in-engine-area-focused-300x200.jpg 300w, https:\/\/www.carparts.com\/blog\/wp-content\/uploads\/2022\/07\/automotive-ABS-Control-Module-in-engine-area-focused-768x512.jpg 768w, https:\/\/www.carparts.com\/blog\/wp-content\/uploads\/2022\/07\/automotive-ABS-Control-Module-in-engine-area-focused-1536x1024.jpg 1536w, https:\/\/www.carparts.com\/blog\/wp-content\/uploads\/2022\/07\/automotive-ABS-Control-Module-in-engine-area-focused-600x400.jpg 600w, https:\/\/www.carparts.com\/blog\/wp-content\/uploads\/2022\/07\/automotive-ABS-Control-Module-in-engine-area-focused-150x100.jpg 150w, https:\/\/www.carparts.com\/blog\/wp-content\/uploads\/2022\/07\/automotive-ABS-Control-Module-in-engine-area-focused.jpg 1700w\" sizes=\"(max-width: 1024px) 100vw, 1024px\"><figcaption>If the ABS module detects that wheel lockup is about to take place, it will command the hydraulic modulator to regulate fluid pressure accordingly.<\/figcaption><\/figure>\n\n\n\n<h2 class=\"wp-block-heading\">What are the Common Causes of the U0121 Code?<\/h2>\n\n\n\n<ul class=\"wp-block-list\"><li>Dead <a href=\"https:\/\/www.carparts.com\/battery\" target=\"_blank\" rel=\"noreferrer noopener\" aria-label=\"battery\">battery<\/a><\/li><li><a href=\"https:\/\/www.carparts.com\/blog\/what-are-the-symptoms-of-a-bad-abs-module-plus-faq\/\" target=\"_blank\" rel=\"noreferrer noopener\" aria-label=\"Faulty ABS control module\">Faulty ABS control module<\/a><\/li><li>CAN bus issues<\/li><li>Circuit problems, such as damaged <a href=\"https:\/\/www.carparts.com\/electrical-wires\" target=\"_blank\" rel=\"noreferrer noopener\" aria-label=\"wires\">wires<\/a> or poor connections<\/li><\/ul>\n\n\n\n<div id=\"article-search-widget\">\n<div class=\"cp-search\">\n<div align=\"center\">\n<img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/cld.partsimg.com\/image\/upload\/w_auto,dpr_auto\/carparts\/logos\/badge_wordmark\/full_color\/CP_LOGO_COLOUR_RGB\" alt=\"CarParts.com\" width=\"300\" height=\"56\">\n<\/div>\n<form id=\"cpsearchform\" name=\"cpsearchform\" action=\"https:\/\/www.carparts.com\/search\" method=\"get\" target=\"_blank\" accept-charset=\"character_set\" aria-label=\"search CarParts.com\">\n    <input type=\"text\" class=\"keyword\" name=\"q\" placeholder=\"Search for parts on CarParts.com\" value=\"\" aria-label=\"Search CarParts.com\"><input type=\"submit\" class=\"btn-search\" value=\"Search\" aria-label=\"Search\">\n<\/form>\n<\/div>\n<\/div>\n\n\n\n<h2 class=\"wp-block-heading\">What are the Common Symptoms of the U0121 Code?<\/h2>\n\n\n\n<ul class=\"wp-block-list\"><li><a href=\"https:\/\/www.carparts.com\/blog\/brake-system-warning-light-what-does-it-mean\/\" target=\"_blank\" rel=\"noreferrer noopener\" aria-label=\"Illuminated warning lights\">Illuminated warning lights<\/a><\/li><li>ABS performance issues<\/li><\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">How to Diagnose the U0121 Code<\/h2>\n\n\n\n<p>U0121 is a <a href=\"https:\/\/www.carparts.com\/blog\/search-obd2-codes-list\/\" target=\"_blank\" rel=\"noreferrer noopener\" aria-label=\"generic powertrain code\">generic powertrain code<\/a> that can be logged in vehicles with on-board diagnostics (OBD). Although this fault code is common, its steps for diagnosis and repair can vary from one vehicle to another.<\/p>\n\n\n\n<p>If you&rsquo;re not familiar with the process of diagnosing trouble codes yet, it&rsquo;s best to have your vehicle checked by a certified mechanic. Otherwise, you can go ahead and do the job yourself.<\/p>\n\n\n\n<p>Check out the video below to get an idea of what the process might involve.<\/p>\n\n\n\n<figure class=\"wp-block-embed is-type-video is-provider-youtube wp-block-embed-youtube wp-embed-aspect-16-9 wp-has-aspect-ratio\"><div class=\"wp-block-embed__wrapper\">\n<iframe loading=\"lazy\" title='U0121 DIAG\/FIXED Chevy \"NO COMMUNICATION\"' width=\"500\" height=\"281\" src=\"https:\/\/www.youtube.com\/embed\/ZzB_crXwx60?feature=oembed\" frameborder=\"0\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share\" referrerpolicy=\"strict-origin-when-cross-origin\" allowfullscreen><\/iframe>\n<\/div><\/figure>\n\n\n\n<h2 class=\"wp-block-heading\">How to Fix the U0121 Code<\/h2>\n\n\n\n<p>Without the right tools and know-how, attempting to fix a U0121 code can be difficult. It can even lead to further complications if done incorrectly. So if you&rsquo;re not confident with your DIY skills yet, it&rsquo;s a good idea to bring your vehicle to the nearest repair shop and have a certified professional do the repairs for you.<\/p>\n\n\n\n<p>But if you think you can do it, make sure you have everything you need before proceeding. It&rsquo;s also a good idea to check out vehicle-specific repair information like those from Chilton or an ALLDATA subscription before you start.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">How to Find a New ABS Control Module for Your Vehicle Online<\/h2>\n\n\n\n<p>Once you confirm that a faulty ABS control module triggered the U0121 code in your vehicle, it&rsquo;s best to replace the part immediately. If you continue driving without replacing the control module, your vehicle might be more vulnerable to skidding on slippery roads because the ABS might not work. For a quality replacement ABS control module that fits your car and budget, look no further than CarParts.com.<\/p>\n\n\n\n<p>At <a href=\"https:\/\/www.carparts.com\/\" target=\"_blank\" rel=\"noreferrer noopener\" aria-label=\"CarParts.com\">CarParts.com<\/a>, you will surely find a part or accessory that will fit your vehicle. Simply select the year, make, model, and engine of your car or truck on our website&rsquo;s vehicle selector to pull up the appropriate products from our catalog. Our parts are ready to ship from one of our distribution centers located across the US. If you live in the continental U.S. and order by 12 p.m. EST, you can expect to receive your new ABS control module in a few working days.<\/p>\n\n\n\n<p>Don&rsquo;t drive with a bad ABS control module and get a new one with a few clicks of a mouse or taps of your mobile phone&rsquo;s screen.<em> <\/em>Visit CarParts.com now and enjoy great deals on our <a href=\"https:\/\/www.carparts.com\/abs-control-module\" target=\"_blank\" rel=\"noreferrer noopener\" aria-label=\"ABS control modules\">ABS control modules<\/a>.<\/p>\n<\/body><\/html>\n","protected":false},"excerpt":{"rendered":"<p><span class=\"span-reading-time rt-reading-time\" style=\"display: block;\"><span class=\"rt-label rt-prefix\">Reading Time: <\/span> <span class=\"rt-time\"> 3<\/span> <span class=\"rt-label rt-postfix\">minutes<\/span><\/span>Most modern vehicles are equipped with an anti-lock braking system (ABS). The system prevents the wheels from locking up during&#8230; <a href=\"https:\/\/www.carparts.com\/blog\/u0121-code-lost-communication-with-anti-lock-braking-system-abs-module\/\" rel=\"nofollow\">Read More<\/a><\/p>\n","protected":false},"author":4,"featured_media":70836,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"_genesis_hide_title":false,"_genesis_hide_breadcrumbs":false,"_genesis_hide_singular_image":false,"_genesis_hide_footer_widgets":false,"_genesis_custom_body_class":"","_genesis_custom_post_class":"","_genesis_layout":"","footnotes":""},"categories":[1314],"tags":[1863,73],"ppma_author":[2607,2855],"class_list":{"0":"post-70834","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-obd-ii-trouble-codes","8":"tag-abs-control-module","9":"tag-battery","10":"entry"},"acf":{"adrotate_specific_mobile_ad":"","adrotate_specific_desktop_ad":""},"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v27.5 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>U0121 Code: Lost Communication With Anti-Lock Braking System (ABS) Module - In The Garage with CarParts.com<\/title>\n<meta name=\"description\" content=\"Learn what the U0121 code means, the most common causes and symptoms associated with it, and how best to approach a solution. Read on.\" \/>\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.carparts.com\/blog\/u0121-code-lost-communication-with-anti-lock-braking-system-abs-module\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"U0121 Code: Lost Communication With Anti-Lock Braking System (ABS) Module - In The Garage with CarParts.com\" \/>\n<meta property=\"og:description\" content=\"Learn what the U0121 code means, the most common causes and symptoms associated with it, and how best to approach a solution. 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