back to article Thousands of Teslas recalled over brake fluid bug

Got a Tesla Model X built between 2021 and 2023? The US National Highway Traffic Safety Administration (NHTSA) has said Tesla will recall almost 55,000 vehicles over a brake fluid warning sensor. Tesla submitted a report regarding the issue on October 11 and an acknowledgment was sent out on October 16. Some 54,676 vehicles …

  1. PRR Silver badge

    I was taught to check my brake fluid manually. Is that no longer possible on Tesla? (It is well-described in my 2023 Toyota Owner Manual.)

    I know that even unto the 1991 Miata there was a float-switch, but that has given trouble, both false alarm and fail to alert (sticky switch or float).

    1. A. Coatsworth Silver badge

      To mangle the well-know proverb: "if a sensor throws an alarm, and no app records it, did it happen?"

    2. Kevin McMurtrie Silver badge

      The tank could run low in just a few pedal presses due to the extreme pressure. There aren't many places where failure will only cause a slow leak.

      1. BenDwire Silver badge

        You obviously haven't ever owned a British Leyland car from the 1970's that had no paint left on the bulkhead (firewall) due to a weeping joint between the reservoir and the master cylinder. They don't make 'em like that any more ...

        Icon - because they couldn't

        1. Anonymous Coward
          Anonymous Coward

          You wouldn't be allowed to make them like that. The master cylinder would be outlawed.

          1. John Brown (no body) Silver badge

            Are we still allowed to call it a "master" cylinder these days?

        2. CrazyOldCatMan Silver badge

          You obviously haven't ever owned a British Leyland car from the 1970's

          Or a 1966 Morris Minor. I borrowed my wifes' one day (my Honda was in for a service) and, when I first went to brake, my foot went flat to the floor.. Frantic pumping of the brake pedal eventually resulted in the usual faint rubbing noises and the car eventually came to a stop.

          I mentioned it to her - her response? "It does that all the time, I just pump the brake pedel a bit before I drive off"!

          The next week it went to the Morris Minor centre in Brislington to have disk brakes fitted on the front. Not had a problem since.

          It's still got the orginal engine block and cylinder head. Replaced the crankshaft about 20 years ago. It's got -tive earth conversion, a proper alternator, heated rear *and* front windows and is currently using Mini Metro seats (headrests). It's not converted for unleaded (shortens the valve and crankshaft life) but instead uses an in-line tin device that the fuel flows over on its way to the carb. Seems to work a treat.

      2. PRR Silver badge

        > The tank could run low in just a few pedal presses due to the extreme pressure. There aren't many places where failure will only cause a slow leak.

        Twice I have had the fun of pedal dropping right to floor, total burst pipe/hose. (Once at the traffic light at the bottom of the hill.)

        All pedals drop slowly as the pads wear (drums not so much cuz (self) adjusters). But the volume of the pot is sized larger than the total pad volume so you run out of pad before you normally run out of fluid.

        ALL breaks leak. Not so much cuz pressure; they know that and design the seals for the need. But no seal is perfect and over-tight seals make sticky brakes. (I've had that too, 500 miles from home.) The foot-end cylinder (we won't say master) has a little extra capacity to cover expected seepage.

        Henry Ford resisted using hydraulic brakes because he thought they were unsafe. He was not wrong, but Lockheed's (and other's) determination and standardized reliability has turned out better than most mechanical brakes (especially on the steerable wheels).

        And no, a seepy main cylinder is not illegal. That's where you look when you can't find the leak (on some cars it runs inside and you have to lift the carpet.)

    3. imanidiot Silver badge

      In a lot of modern cars the car manufacturers (idiots that they are) assume that all owners are idiots and make even the most basic of service tasks like checking fluid levels nearly impossible.

  2. John Robson Silver badge

    We really do need a new name

    For these "required updates" as opposed to a "recall" because they aren't actually recalling anything.

    In the same way M$ computers aren't "recalled" each patch Tuesday.

    1. Ken Moorhouse Silver badge

      Re: We really do need a new name

      How about recoil?

      1. Doctor Syntax Silver badge

        Re: We really do need a new name

        The crumple zone should stop it recoiling.

    2. Roland6 Silver badge

      Re: We really do need a new name

      Failure to implement required functionality.

      What is clear Tesla set the wrong value in their controller software for some thing as well known and understood as a brake fluid sensor. Which raises questions about their attention to other important operational variables such as their much hyped driver assist features …

    3. Lee D Silver badge

      Re: We really do need a new name


      "Mass mandatory critical software fix for potentially lethal issue".

      What's that? Oh, you're happy calling it a recall instead?

  3. Gene Cash Silver badge

    Lucas called

    They're suing over their patent on electrical shorts in road-going vehicles.

    1. David 132 Silver badge

      Re: Lucas called

      Eh, ignore them, they’re just blowing smoke :)

      1. CrazyOldCatMan Silver badge

        Re: Lucas called

        Eh, ignore them, they’re just blowing smoke :)

        Along with the Ducatti bike parked alongside..

        (Italian electrics and British weather are not particularly compatible - to be fair, it mostly results in the bike failing to power up, let alone start..)

  4. Ken Moorhouse Silver badge trundle to their nearest service center

    In other news Tesla Service Center|re's will be modified to have doors at both ends.

    Just in case drivers are unable to stop in time.

  5. elsergiovolador Silver badge


    // uint8_t brakeFluidStatus = getBrakeFluidStatus(&car);

    // if (brakeFluidStatus & BRAKE_FLUID_STATUS_LOW_FLAG) {

    // setBrakeFluidLowLight(&car, true);

    // }

    // ^^ don't bother with the sensor


    uint32_t timeSinceLastService = getTimeSinceLastService(&car);

    if (timeSinceLastService > 94608000) {

    // if it has not been serviced in 3 years, just nudge the user to visit one

    setBrakeFluidLowLight(&car, true);

    if (timeSinceLastService > 126227704) {

    // ok this user is taking the piss. Let's set the engine warning light

    setEngineFailureLight(&car, true);



  6. Anonymous Coward
    Anonymous Coward

    There was me expecting to see pictures of ladybirds spilling out of master cylinders.....

    1. Doctor Syntax Silver badge

      I was thinking of micro-organisms. Two countries separated by a common language.

      1. abend0c4 Silver badge

        It's the macro organisms you've got to watch out for.

        1. Anonymous Coward
          Anonymous Coward

          In a similar vein - don't use your windscreen washers to try and remove monkeys off your car bonnet (hood) when visiting safari parks. That's what my friend tells me - the little sods, then try and drink it damaging the nozzles in the process......

          1. imanidiot Silver badge

            Apparently some windscreen washer fluids contain ethylene glycol which is sweet tasting, and also very damaging to the kidneys. More commonly it's methanol, which is ALSO tasty to primates and very toxic.Either way it's probably a bad idea to let the cretins drink any of it.

            1. CrazyOldCatMan Silver badge

              probably a bad idea to let the cretins drink any of it

              And the monkeys.

              It's also a good way to lose your windscreen wipers.

              1. John Brown (no body) Silver badge

                Yes. The correct solution if you are concerned about monkeys on your car bonnet is the UK is to either NOT visit a safari park or to park up and take the bus trip guided tour option instead. :-)

  7. spireite Silver badge

    I guess while they investigated, looking for the problem, the PR department could only say the situation is fluid.

  8. Winkypop Silver badge
    Big Brother


    Are Tesla owners even allowed access to their cars service areas?

    His Muskiness doesn’t like those with poor faith…

    1. Anonymous Coward
      Anonymous Coward

      Re: Permission

      Well they do provide a number of DIY guides for basic maintenance:

      And a free subscription (aimed at professionals but accessible to everyone) that covers:

      Service Manuals

      Parts Manuals

      Wiring Diagrams and Connector References

      Service Bulletins

      So, yeah, if you are up for it, you can certainly have a go...

  9. Bebu Silver badge


    I was surprised Teslas had hydraulic brakes :)

    I assumed in Musk's best of all possible worlds, the breaking would be all electric - regenerative breaking to slow down and emergency breaking - shove in a pile of amps from the battery to give it a bit of welly. Of course all under the control of the included safety critical software. :)

    Drive in a Tesla? Sorry mate I'll stick to my Leyland P76 ;)

    1. Snake Silver badge

      Re: Surprised....

      Wait, wait - a Leyland actually drives? As in, it can roll the tyres without a major part exploding??

      Shirley you jest ;D

      1. John Brown (no body) Silver badge

        Re: Surprised....

        You just need two friends to push :-)

    2. Potty Professor

      Re: Breaking....

      They break all the time, it's braking that's the problem.

  10. CowHorseFrog Silver badge

    Its good too see how Musk shares his software engineering particularly his wisdom and best practices around automated testing of software, this is yet another fine example of this.

  11. Anonymous Coward
    Anonymous Coward

    This is why some things should be hardwired

    Why would the sensor need to go through the computer? Critical safety systems are typically direct-wired, at least in industry, as you can't trust that the computer will respond in time, or correctly. (It usually will, but "usually" isn't good enough for safety systems.) To be fair, this is more of a warning, but it's a "pull over right now" warning.

    (Automation engineer, with 1.5 decades experience in instrumentation.)

    1. Anonymous Coward
      Anonymous Coward

      Re: This is why some things should be hardwired

      Hard wired to what exactly?

      Teslas don't have little rows of warning lights (or rows of switches).

      If you want something displayed to the driver, it has to go on the flat screen. Which means the computer needs to do it...

      And this isn't just Teslas any more. Many vehicles basically now have a flat screen display instead of the little rows of lights.

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