{"id":77090,"date":"2022-11-01T18:49:17","date_gmt":"2022-11-02T01:49:17","guid":{"rendered":"https:\/\/blogv2prod.wpenginepowered.com\/blog\/?p=77090"},"modified":"2023-09-15T01:43:51","modified_gmt":"2023-09-15T08:43:51","slug":"p0840-code-transmission-fluid-pressure-sensor-switch-a-circuit","status":"publish","type":"post","link":"https:\/\/www.carparts.com\/blog\/p0840-code-transmission-fluid-pressure-sensor-switch-a-circuit\/","title":{"rendered":"P0840 Code: Transmission Fluid Pressure Sensor\/Switch \u201cA\u201d Circuit"},"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_b8ca5f-35 > .kt-inside-inner-col{border-top-width:0px;border-right-width:0px;border-bottom-width:0px;border-left-width:0px;}.kadence-column_b8ca5f-35 > .kt-inside-inner-col,.kadence-column_b8ca5f-35 > .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_b8ca5f-35 > .kt-inside-inner-col{column-gap:var(--global-kb-gap-sm, 1rem);}.kadence-column_b8ca5f-35 > .kt-inside-inner-col{flex-direction:column;}.kadence-column_b8ca5f-35 > .kt-inside-inner-col > .aligncenter{width:100%;}.kadence-column_b8ca5f-35 > .kt-inside-inner-col:before{opacity:0.3;}.kadence-column_b8ca5f-35{position:relative;}@media all and (max-width: 1024px){.kadence-column_b8ca5f-35 > .kt-inside-inner-col{flex-direction:column;justify-content:center;}}@media all and (max-width: 767px){.kadence-column_b8ca5f-35 > .kt-inside-inner-col{flex-direction:column;justify-content:center;}}<\/style>\n<div class=\"wp-block-kadence-column inner-column-1 kadence-column_b8ca5f-35 qk-look-widget\"><div class=\"kt-inside-inner-col\">\n<div class=\"wp-block-ultimate-post-row ultp-block-df42c7  qk-main-wrap\"><div class=\"ultp-row-wrapper\"><div class=\"ultp-row-content\">\n<div class=\"wp-block-ultimate-post-column ultp-block-f6506d\"><div class=\"ultp-column-wrapper\"><style>.wp-block-kadence-advancedheading.kt-adv-heading_3007c3-4a, .wp-block-kadence-advancedheading.kt-adv-heading_3007c3-4a[data-kb-block=\"kb-adv-heading_3007c3-4a\"]{text-align:center;font-size:20px;font-style:normal;}.wp-block-kadence-advancedheading.kt-adv-heading_3007c3-4a mark.kt-highlight, .wp-block-kadence-advancedheading.kt-adv-heading_3007c3-4a[data-kb-block=\"kb-adv-heading_3007c3-4a\"] 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_3007c3-4a img.kb-inline-image, .wp-block-kadence-advancedheading.kt-adv-heading_3007c3-4a[data-kb-block=\"kb-adv-heading_3007c3-4a\"] img.kb-inline-image{width:150px;vertical-align:baseline;}<\/style>\n<div class=\"kt-adv-heading_3007c3-4a summary-title wp-block-kadence-advancedheading\" data-kb-block=\"kb-adv-heading_3007c3-4a\"><span>Summary<\/span><\/div>\n\n\n\n<ul class=\"wp-block-list\"><li>On-board diagnostics will log a P0840 code when there&rsquo;s an electrical fault in the transmission fluid pressure sensor\/switch.<\/li><li>Aside from electrical issues, low transmission fluid, valve body problems, and internal transmission failure can trigger this code.<\/li><li>If this code is present, you&rsquo;ll notice symptoms like shifting problems, poor fuel economy, and your vehicle getting stuck in limp mode.<\/li><\/ul>\n<\/div><\/div>\n<\/div><\/div><\/div>\n<\/div><\/div>\n\n\n\n\n\n<p>The transmission fluid pressure sensor relays information that the <a href=\"https:\/\/www.carparts.com\/engine-control-module\" target=\"_blank\" rel=\"noreferrer noopener\" aria-label=\"powertrain control module\">powertrain control module<\/a> (PCM) or <a href=\"https:\/\/www.carparts.com\/transmission-control-module\" target=\"_blank\" rel=\"noreferrer noopener\" aria-label=\"transmission control module\">transmission control module<\/a> (TCM) needs to engage the clutches and shift gears smoothly while driving. Fluid pressure in the system can be affected by problems with the hydraulic clutch or pressure switch.<\/p>\n\n\n\n<p>If the PCM detects an abnormality with the transmission fluid pressure, on-board diagnostics (OBD) will log a P0840 code.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">What Does the P0840 Code Mean?<\/h2>\n\n\n\n<p><a href=\"https:\/\/www.carparts.com\/blog\/search-obd2-codes-list\/\" target=\"_blank\" rel=\"noreferrer noopener\" aria-label=\"Diagnostic trouble code\">Diagnostic trouble code<\/a> (DTC) P0840 stands for &ldquo;Transmission Fluid Pressure Sensor\/Switch &lsquo;A&rsquo; Circuit.&rdquo;<\/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\/11\/transmission-fluid-pressure-sensor-causing-p0840-code-1024x682.jpg\" alt=\"transmission fluid pressure sensor causing p0840 code\" class=\"wp-image-77144\" width=\"1024\" height=\"682\" srcset=\"https:\/\/www.carparts.com\/blog\/wp-content\/uploads\/2022\/11\/transmission-fluid-pressure-sensor-causing-p0840-code-1024x682.jpg 1024w, https:\/\/www.carparts.com\/blog\/wp-content\/uploads\/2022\/11\/transmission-fluid-pressure-sensor-causing-p0840-code-300x200.jpg 300w, https:\/\/www.carparts.com\/blog\/wp-content\/uploads\/2022\/11\/transmission-fluid-pressure-sensor-causing-p0840-code-768x512.jpg 768w, https:\/\/www.carparts.com\/blog\/wp-content\/uploads\/2022\/11\/transmission-fluid-pressure-sensor-causing-p0840-code-1536x1024.jpg 1536w, https:\/\/www.carparts.com\/blog\/wp-content\/uploads\/2022\/11\/transmission-fluid-pressure-sensor-causing-p0840-code-600x400.jpg 600w, https:\/\/www.carparts.com\/blog\/wp-content\/uploads\/2022\/11\/transmission-fluid-pressure-sensor-causing-p0840-code-1200x800.jpg 1200w, https:\/\/www.carparts.com\/blog\/wp-content\/uploads\/2022\/11\/transmission-fluid-pressure-sensor-causing-p0840-code-150x100.jpg 150w, https:\/\/www.carparts.com\/blog\/wp-content\/uploads\/2022\/11\/transmission-fluid-pressure-sensor-causing-p0840-code.jpg 2000w\" sizes=\"(max-width: 1024px) 100vw, 1024px\"><figcaption>The transmission fluid pressure sensor sends a voltage signal to the PCM, informing the computer of the hydraulic pressure within the transmission.<\/figcaption><\/figure>\n\n\n\n<p>The <a href=\"https:\/\/www.carparts.com\/auto-trans-oil-pressure-sensor\" target=\"_blank\" rel=\"noreferrer noopener\" aria-label=\"transmission fluid pressure sensor\">transmission fluid pressure sensor<\/a> sends a voltage signal to the PCM, informing the computer of the hydraulic pressure within the transmission. Using this information, the PCM or TCM will control output devices, such as the pressure control solenoid.<\/p>\n\n\n\n<p>The transmission fluid pressure sensor is usually subject to electrical fault, causing it to send operating voltage input that&rsquo;s outside the normal range. This issue can trigger a P0840 code.<\/p>\n\n\n\n<p><strong><em>Note:<\/em><\/strong><em> The definition of code P0840 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<h2 class=\"wp-block-heading\">What are the Common Causes of the P0840 Code?<\/h2>\n\n\n\n<ul class=\"wp-block-list\"><li>Transmission fluid pressure sensor failure<\/li><li>Wiring issues<\/li><li><a href=\"https:\/\/www.carparts.com\/blog\/how-much-is-transmission-fluid-plus-answers-to-commonly-asked-questions\" target=\"_blank\" rel=\"noreferrer noopener\" aria-label=\"Low transmission fluid\">Low transmission fluid<\/a><\/li><li><a href=\"https:\/\/www.carparts.com\/blog\/car-pcm-meaning-symptoms-of-failure-and-more\/\" target=\"_blank\" rel=\"noreferrer noopener\" aria-label=\"Powertrain control module failure\">Powertrain control module failure<\/a><\/li><li>Internal transmission failure<\/li><li><a href=\"https:\/\/www.carparts.com\/blog\/transmission-valve-body-what-it-is-how-it-works-and-more\/\" target=\"_blank\" rel=\"noreferrer noopener\" aria-label=\"Valve body problems\">Valve body problems<\/a><\/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 P0840 Code?<\/h2>\n\n\n\n<ul class=\"wp-block-list\"><li><a href=\"https:\/\/www.carparts.com\/blog\/check-engine-light-flashing\/\" target=\"_blank\" rel=\"noreferrer noopener\" aria-label=\"Illuminated check engine light\">Illuminated check engine light<\/a><\/li><li>Transmission not shifting properly<\/li><li>Increased fuel consumption<\/li><li>Vehicle in <a href=\"https:\/\/www.carparts.com\/blog\/web-stories\/what-is-limp-mode\/\" target=\"_blank\" rel=\"noreferrer noopener\" aria-label=\"limp mode\">limp mode<\/a><\/li><\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">How to Diagnose the P0840 Code<\/h2>\n\n\n\n<p>Code P0840 is a generic powertrain code that vehicles with an OBD-II system can log. However, keep in mind that factors like vehicle specifications (year, make, and model) can alter the diagnostic process.<\/p>\n\n\n\n<p>Diagnosing this type of code might involve the use of a scan tool and checking the affected system for damaged wiring. If you&rsquo;re not familiar with how the process works, you can always let a certified mechanic do the job for you. But if you think you can handle the task on your own, then you can go ahead and perform the necessary procedures.<\/p>\n\n\n\n<p>To help you out, here&rsquo;s a short clip that shows 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=\"2011 Nissan Maxima Transmission Problem Code P0840\/P0845 Diagnose Result\" width=\"500\" height=\"281\" src=\"https:\/\/www.youtube.com\/embed\/H2oAovY4qAU?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 P0840 Code<\/h2>\n\n\n\n<p>Resolving a P0840 code can be tricky, especially if you don&rsquo;t have the right equipment and technical knowledge. If done incorrectly, your vehicle could develop more problems, which might lead to expensive repairs. If you&rsquo;re not confident with your DIY skills yet, it&rsquo;s best to bring your vehicle to the nearest auto repair shop and have a trained professional work on your daily driver.<\/p>\n\n\n\n<p>But if you have some experience fixing problems like this one, then you already know that there&rsquo;s not a single solution that works for all makes and models. So before you begin, make sure to consult the appropriate repair manual. Guides like those from Chilton or an ALLDATA subscription contain vehicle-specific repair information, so you might want to check those out.<\/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>The transmission fluid pressure sensor relays information that the powertrain control module (PCM) or transmission control module (TCM) needs to&#8230; <a href=\"https:\/\/www.carparts.com\/blog\/p0840-code-transmission-fluid-pressure-sensor-switch-a-circuit\/\" rel=\"nofollow\">Read More<\/a><\/p>\n","protected":false},"author":4,"featured_media":77145,"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":[2158,1323,1838,1222],"ppma_author":[2607,2855],"class_list":{"0":"post-77090","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-obd-ii-trouble-codes","8":"tag-auto-trans-oil-pressure-sensor","9":"tag-engine-control-module-2","10":"tag-oil-pressure-sensor","11":"tag-transmission-control-module","12":"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>P0840 Code: Transmission Fluid Pressure Sensor\/Switch \u201cA\u201d Circuit - In The Garage with CarParts.com<\/title>\n<meta name=\"description\" content=\"Learn what the P0840 code means and the most common causes that could trigger it.\" \/>\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\/p0840-code-transmission-fluid-pressure-sensor-switch-a-circuit\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"P0840 Code: Transmission Fluid Pressure Sensor\/Switch \u201cA\u201d Circuit - In The Garage with CarParts.com\" \/>\n<meta property=\"og:description\" content=\"Learn what the P0840 code means and the most common causes that could trigger it.\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.carparts.com\/blog\/p0840-code-transmission-fluid-pressure-sensor-switch-a-circuit\/\" \/>\n<meta property=\"og:site_name\" content=\"In The Garage with CarParts.com\" \/>\n<meta property=\"article:publisher\" content=\"https:\/\/www.facebook.com\/carpartscom\" \/>\n<meta property=\"article:published_time\" content=\"2022-11-02T01:49:17+00:00\" \/>\n<meta property=\"article:modified_time\" content=\"2023-09-15T08:43:51+00:00\" \/>\n<meta property=\"og:image\" content=\"https:\/\/www.carparts.com\/blog\/wp-content\/uploads\/2022\/10\/mechanic-uses-lamp-to-find-transmission-fluid-pressure-sensor.jpg\" \/>\n\t<meta property=\"og:image:width\" content=\"2000\" \/>\n\t<meta property=\"og:image:height\" content=\"1333\" \/>\n\t<meta property=\"og:image:type\" content=\"image\/jpeg\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:creator\" content=\"@carpartscom\" \/>\n<meta name=\"twitter:site\" content=\"@carpartscom\" \/>\n<meta name=\"twitter:label1\" content=\"Written by\" \/>\n\t<meta name=\"twitter:data1\" content=\"\" \/>\n\t<meta name=\"twitter:label2\" content=\"Est. reading time\" \/>\n\t<meta name=\"twitter:data2\" content=\"3 minutes\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\\\/\\\/schema.org\",\"@graph\":[{\"@type\":\"Article\",\"@id\":\"https:\\\/\\\/www.carparts.com\\\/blog\\\/p0840-code-transmission-fluid-pressure-sensor-switch-a-circuit\\\/#article\",\"isPartOf\":{\"@id\":\"https:\\\/\\\/www.carparts.com\\\/blog\\\/p0840-code-transmission-fluid-pressure-sensor-switch-a-circuit\\\/\"},\"author\":[{\"@type\":\"Person\",\"$id\":\"4\",\"name\":\"CarParts.com Research Team\",\"jobTitle\":\"Expert Automotive Writer\",\"description\":\"The CarParts.com Research Team is composed of experienced automotive and tech writers working with (ASE)-certified automobile technicians and automotive journalists to bring up-to-date, helpful information to car owners in the US. 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