Faults before the light
Cars log "pending" codes before the check-engine light comes on. Tachwise reads them along with the confirmed ones, and Otto explains each one: what it means and how soon it needs a look.
Our board is ready for production · Join the waitlist
Your car can't talk. Tachwise can.
Tachwise reads your car's OBD-II port, and Otto, our owl, explains what it finds in plain language: trouble codes (including the pending ones that come before the check-engine light), how the battery is holding up, and live data. It also keeps track of what's due and what's wearing: oil, brakes, tires and the rest. Made for everyday drivers, and still handy if you do your own wrenching.
The beta works with your own Bluetooth ELM327 dongle: in Chrome on Android or a desktop, or on iPhone through TestFlight.
Freeapp beta and waitlist
No paymenttaken for the device yet
Your phoneis where your data lives
The Tachwise device
The whole device
The whole device
is the plug.
No cable, and no box hanging under the dash: the plug is built into the case, so it goes straight into your car's OBD-II port and stays there. This is the first-run design, drawn from its CAD files. Turn it, and open it up.
- Plug built in The 16-pin OBD-II plug is part of the case. The port is usually under the dash, near the steering column.
- 2.2 × 4.2 in With the plug. The body is just over half an inch thick, about an inch at the plug.
- Our own board inside A six-layer circuit board we designed for the port, ready for production. Open the case to see it.
- Otto on top, a QR code underneath Turn it over: the code takes your phone to the Tachwise app.
- Nylon shell The first cases are 3D-printed in tough PA12 nylon.
Free. No payment, no deposit. The first boards go to testers from the waitlist.
This device has not been authorized as required by the rules of the Federal Communications Commission. This device is not, and may not be, offered for sale or lease, or sold or leased, until authorization is obtained.
What it watches
What your car reports.
What your car reports.
What it's due for.
Tachwise reads what the car shares through its OBD-II port. It also keeps track of the parts and fluids that wear out or come due, so a service doesn't sneak up on you.
What it reads from the car
Readings that come straight from the port, explained by Otto.
Live data and trips
Speed, rpm, coolant temperature and fuel trims while you drive, with each trip kept on your phone. With a dongle, that's every drive your phone was connected for.
EV and hybrid battery
On supported models: the pack's state of charge and state of health, and charging sessions. First up are Hyundai and Kia EVs and the Nissan Leaf, built from community-documented data that we haven't yet checked on a real car. Hybrids get the battery life reading where the car shares it.
Tachwise device
The 12 V battery, even while it's parked
Most OBD apps only see your car while your phone is in it. The device stays in the port. After you park, a healthy battery settles to a steady voltage overnight; a tired one sags, and a hidden drain keeps pulling it down. The device samples that resting voltage while the car sleeps, and how far the voltage dips at every start, so Otto can say "your battery is getting weak" before a cold morning says it for him.
What it keeps track of
Standard OBD-II data doesn't include brake pad wear, tire tread or oil condition, so Tachwise doesn't pretend to measure them. It estimates when each one is due from how far you drive and the services you log, against an interval you can edit.
In the app beta- Oil and filterBy distance or months, whichever comes first. Lots of short trips bring it forward.
- BrakesA reminder to have the pads and rotors inspected, and brake fluid by age and distance.
- Tires and rotationRotation by distance, a monthly pressure check, and tread depth and tire age from what you enter.
- Spark plugsBy distance. Engines vary a lot here, so the default is the cautious one.
- Transmission fluidBy distance. Some makers call it "lifetime" or "inspect only", so check your manual.
- CoolantBy distance and age, whichever comes first.
- Air and cabin filtersBy distance and months.
- Belts and wipersDrive belt and wiper blades, and a timing belt if your engine has one.
- 12 V batteryA yearly test reminder, alongside the voltage readings above.
- Hybrid and EV itemsHybrid battery checks, EV battery coolant and reduction-gear fluid. No oil or plugs on an EV.
Every item is estimated from your driving and service log, against an interval you can edit. None of them is a measurement of the part.
- Distance drivenFrom the car's odometer reading where it shares one, otherwise from the drives the app sees, corrected each time you log the dashboard figure.
- Your service logLog what was done and when, and that item's countdown starts again from there.
- Intervals you can editEach item starts at the cautious end of what owners' manuals say, with the sources linked. Check it against your own manual and change it in one tap.
- Add to calendarPut a reminder in Google Calendar, Apple Calendar or Outlook. It says it's an estimate.
Otto explains. He never nags.
Otto is the voice of the app. He tells you what changed and why it matters, in a sentence you'd use yourself, and stays quiet when there's nothing to say.
Your car logged a pending code for the downstream oxygen sensor. No light yet. Keep an eye on it; I will too.
Tire rotation is due in about 500 miles.
Your battery rested at 12.6 V overnight. That's normal.
The Tachwise device has run in a car as a prototype, and its own circuit board is ready for production. It isn't for sale yet. The roadmap says where each piece stands.
Get started
Two ways in.
Start today with a dongle you may already own, or get in line for the device that keeps watching when you're not there.
With your own ELM327 dongle
Have a Bluetooth Low Energy ELM327 dongle (Veepeak, Vgate and many others)? Open the Tachwise app beta, plug the dongle in and connect. It's free and needs no account.
- On Android or a computer, open it in Chrome with Bluetooth. Nothing to install.
- On iPhone, join through TestFlight, Apple's app for betas: open the link below on your phone, install TestFlight when asked, then install Tachwise from it.
- On Android, Chrome works today, nothing to install. A Play Store beta is on its way and needs Google's review first; to be in the first group, email support@tachwise.com from the Google account on your phone.
- Only while you're connected. A dongle sees the car while your phone is in it and the app is open.
- It's a beta. Expect rough edges, and tell us which dongle you used.
app.tachwise.com on Android and desktop · TestFlight on iPhone
The Tachwise device
A small unit that stays plugged into the port and keeps watching while the car is parked: the battery's resting curve, the cranking dip, and faults as they appear. Your phone doesn't need to be anywhere near it.
- Where it is: proven on the road as a prototype, reading live data and sending it to the phone over Bluetooth. Its own circuit board is designed and ready for production.
- First boards: to hand-picked testers from the waitlist, in their own cars. The car you enter helps us choose.
- Ordering: waitlist members get first call, and we'll contact you when orders open. Want one? Email us any time.
- Price: set once production quotes are in. No payment is taken to join.
Free. Takes a minute.
This device has not been authorized as required by the rules of the Federal Communications Commission. This device is not, and may not be, offered for sale or lease, or sold or leased, until authorization is obtained.
Built for real winters
Cold mornings
Cold mornings
are where batteries quit.
A battery that seemed fine in October can fail to turn the engine over on the first 0 °F morning, because cold cuts what it can deliver just when the engine is hardest to turn over. You can usually see that coming: the resting voltage slips and the cranking dip deepens over weeks, and that's why the device is being built to keep watching while the car sits in the driveway.
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Cold starts firstBattery health is the first thing the device is being built to watch.
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Your data stays on your phoneSharing with Tachwise is off unless you switch it on.
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Measured, then claimedWe only say the device does something once we've seen it do it.
Roadmap
From bench to driveway.
Where each piece actually stands today.
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Done
A prototype proves itself on the road
Our firmware, on development boards, has run in a car on the road: reading live data from the OBD-II port and sending it to the phone over Bluetooth.
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Done
Our own circuit board, ready for production
Designed from the ground up for the OBD-II port, with the plug built right in so the whole device is one small unit. Laid out, checked by independent design reviews, and ready for its first production run.
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Now
App beta with your own dongle
The app at app.tachwise.com connects to Bluetooth ELM327 dongles in Chrome, and on iPhone through TestFlight. Early, and we're learning which dongles behave.
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Now
The first boards
We're lining up the first production run. The first boards go to hand-picked testers from the waitlist, in their own cars. First milestone: a full night in a real car.
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Next
Compliance testing
Emissions testing to FCC and ISED rules, which every electronic device needs before it's sold. The price gets set when production quotes and test costs are in.
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Next
Orders open, waitlist first
We contact waitlist members first to place their orders. Nothing is charged before your device is ready to ship.
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Vision
Otto gets smarter
Where we want to take it: asking Otto questions about your car in plain words, spotting wear early from slow drifts in fuel trims, and pothole and hard-braking events from the device's motion sensor. Ideas we're working toward, not features you can use today.
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When it's ready
The device ships
No date until we can keep it. The waitlist hears first.
FAQ
Straight answers.
Which dongles work with the app beta?
Bluetooth Low Energy (BLE) ELM327 dongles. We're building against the most common ones: the Veepeak OBDCheck BLE and BLE+, and the Vgate iCar Pro BLE 4.0. The OBDLink CX and the FIXD sensor should speak the same language, but we haven't confirmed them yet.
Dongles that use classic Bluetooth or Wi-Fi can't be reached from a web page, so they won't work in the beta. BlueDriver, Bouncie and Vyncs are locked to their own apps.
If yours doesn't connect, join the waitlist and pick it under "OBD device you use now". That tells us what to test next.
How does Tachwise know when my brakes or tires are due?
It estimates; it doesn't measure. Standard OBD-II data doesn't include brake pad wear or tire tread, so Tachwise counts the distance you drive (from the car's odometer where it shares one), starts each countdown from the last service you logged, and compares that with a typical interval from owners' manuals. You can change any interval to match your own manual.
Brakes get a reminder to have the pads and rotors inspected, not a replacement date. If a shop measures your pad thickness or tread depth, you can log it. Treat every due date as a reminder to get something checked, not a verdict on the part. Maintenance tracking is in the app beta.
Does it work on my iPhone or Android phone?
Yes, through TestFlight, Apple's app for betas. Open testflight.apple.com/join/4G4GT6k1 on your iPhone, install the free TestFlight app when asked, then install Tachwise from it. The web version doesn't work in Safari, which can't talk to Bluetooth devices from a web page.
On Android it runs in Chrome today, dongle and all. A Play Store beta is on its way and needs Google's review first; email support@tachwise.com from the Google account on your phone and we'll add you to the first group.
What happens to my data?
The app keeps your car's data on your phone. Sending anything to Tachwise is off unless you turn it on, and photos, recordings and routes each have their own switch.
This site counts visits with PostHog without cookies, and never sends your email to analytics. Your waitlist details are used only for Tachwise. We don't sell them.
Tachwise is based in Canada, and your waitlist details are stored on servers in Canada.
Is there a subscription?
The app beta is free. For the device, the plan is a one-time price with no monthly fee for what it does. We set the price once production quotes are in, and nothing is charged before your device is ready to ship.
When does the device ship?
When it's ready and has passed its compliance testing. The first boards go to hand-picked testers from the waitlist; then waitlist members get first call to order.
Can I order one?
Tell us you want one: join the waitlist, or email support@tachwise.com and say so. When orders open, we contact waitlist members first, with the price. Nothing is charged before your device is ready to ship.
This device has not been authorized as required by the rules of the Federal Communications Commission. This device is not, and may not be, offered for sale or lease, or sold or leased, until authorization is obtained.
How are the first testers picked?
From the waitlist, by hand, so the first boards cover as many makes and models as we can. Tell us your car when you join, and tick the email box so we can reach you.
Will it work with my car?
Nearly every car and light truck sold in North America since the late 1990s has an OBD-II port, usually under the dash near the steering column. Tachwise reads the standard data that port shares. How much each car shares varies by make, and the car you put on the waitlist helps us decide what to test first.
Do I have to tick the email box to join?
No. You're on the waitlist either way. Tick it if you'd like us to email you about launches and the beta; you can unsubscribe any time.
Hear first
when it's ready.
Join the free waitlist for the Tachwise device. No payment, no deposit. All we need is your email; tell us what you drive too, if you like, so we test on the cars people actually own.