# What is this warning light on my dash? **URL:** \ **Category:** Factual Questions\ **Created:** [June 2, 2017, 3:35pm UTC](https://boards.straightdope.com/t/what-is-this-warning-light-on-my-dash/787932 "2017-06-02T15:35:08Z")\ **Posts on this page:** 5\ **Page:** 2
**Author:** ![Amateur\_Barbarian](https://avatars.discourse-cdn.com/v4/letter/a/59ef9b/32.png) [@Amateur\_Barbarian](https://boards.straightdope.com/u/Amateur_Barbarian)\ **Post date:** [June 2, 2017, 7:18pm UTC](https://boards.straightdope.com/t/what-is-this-warning-light-on-my-dash/787932/21 "2017-06-02T19:18:34Z")
> [@Machine\_Elf](#): > > As mentioned, your vehicle is equipped with a tire pressure monitoring system (TPMS), and it’s trying to tell you that there’s a problem - either the pressure is low in one of your tires, or the system can’t communicate with all four pressure sensors. Most vehicles I am familiar with show the “butt symbol” only when a tire sensor actually reports a low pressure, and light a separate indicator (on my Honda, it’s a simple “TPMS” when a fault is detected within the system, such as not getting a signal from one or more sensors. I much preferred the Hella TPMS systems I installed in older vehicles, as most (now required) systems in mid-range cars only have these idiot lights, instead of reporting which tire, and actual tire pressures. ---
**Author:** ![DCnDC](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dcndc/32/2842_2.png) [@DCnDC](https://boards.straightdope.com/u/DCnDC)\ **Post date:** [June 2, 2017, 7:46pm UTC](https://boards.straightdope.com/t/what-is-this-warning-light-on-my-dash/787932/22 "2017-06-02T19:46:35Z")
There’s a lot of dash warning lights that are totally useless or hopelessly vague; “Check Engine” light, I’m looking at you. All cars, by law, have on-board diagnostics. Almost all cars manufactured in the last decade or so have some sort of digital display. The car knows what’s wrong, but it won’t tell me. Most people know a “Check Engine” light is bad, but most of the time the car keeps running. Most people know a flashing “Check Engine” light is _really_ bad, but most of the time the car keeps running. But that’s all the information we get. JUST TELL ME WHAT’S WRONG. I know, I can plug in my laptop and check it. I can get a mechanic to plug in and check it, some will do that much for free, others, like the dealership, will charge you $75. The car already has all of the necessary equipment to tell me what’s wrong, on the spot, the moment the error occurs, but it just won’t. JUST TELL ME WHAT’S WRONG. Maybe I can fix it myself, maybe I can’t, but I’ll at least have some idea, and probably enough info to determine whether it’s safe to keep driving or if I should seek immediate help. ---
**Author:** ![silenus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/silenus/32/166_2.png) [@silenus](https://boards.straightdope.com/u/silenus)\ **Post date:** [June 2, 2017, 8:02pm UTC](https://boards.straightdope.com/t/what-is-this-warning-light-on-my-dash/787932/23 "2017-06-02T20:02:10Z")
Our Nissan has a screen in the middle of the dash for all that stuff. The warning light goes on, and it’s a quick toggle through the menu until I hit the “Driver Warnings” menu. Then it tells me exactly what is wrong. It also tells me which tire is low, and by how much. You can get this stuff on just about any new car, for a few more bucks. ---
**Author:** ![aceplace57](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/aceplace57/32/3500_2.png) [@aceplace57](https://boards.straightdope.com/u/aceplace57)\ **Post date:** [June 2, 2017, 9:18pm UTC](https://boards.straightdope.com/t/what-is-this-warning-light-on-my-dash/787932/24 "2017-06-02T21:18:45Z")
> [@Machine\_Elf](#): > > [Here’s your owner’s manual.](http://www.fordservicecontent.com/Ford_Content/catalog/owner_guides/13ecoom2e.pdf) > > Pages 9-10 (PDF pages 10-11) shows “some of the symbols you may see on your vehicle.” > > the TPMS is explained starting on page 266 (PDF page 267). > > Page 89 (PDF page 90) indicates that if there’s a function problem with the TPMS, you’ll get an explicit “TIRE PRESSURE MONITOR FAULT” OR “TIRE PRESSURE SENSOR FAULT”. I guess this means if the TPMS beacon illuminates, the only interpretation is that there’s a tire on your vehicle that is genuinely low on air and needs prompt attention. > > Note that if your tire pressure has gone low enough to trip the sensor, it’s likely you’ve got a real leak that needs repair (unless nobody has ever put air in those tires after the van left the factory). Thank you for the link Machine Elf. I’ll keep the manual on my phone. I had the oil changed last Oct and the tires were checked then. ---
**Author:** ![bob\_2](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bob_2/32/3341_2.png) [@bob\_2](https://boards.straightdope.com/u/bob_2)\ **Post date:** [June 2, 2017, 10:27pm UTC](https://boards.straightdope.com/t/what-is-this-warning-light-on-my-dash/787932/25 "2017-06-02T22:27:42Z")
> [@aceplace57](#): > > I had the oil changed last Oct and the tires were checked then. Electronics notwithstanding, that’s a long time to go without checking pressures and fluid levels. My car has all these bells and whistles, but I still check once a month or so. [Previous page](https://boards.straightdope.com/t/what-is-this-warning-light-on-my-dash/787932.md?page=1)