Your car already knows when its battery is tiring or a sensor is drifting. It just can't tell you. Tachwise reads the car's OBD-II port and Otto, our owl, puts what it finds in plain language: what's fine, what's changing, and what needs a look. 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. iPhone support comes with the native app.
Most OBD apps only see your car while your phone is in it. The Tachwise device stays in the port and keeps watching after you walk away.
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, so Otto can say "your battery is getting weak" before a cold morning says it for him.
Every start pulls the voltage down for a moment. How far it dips, start after start, is one of the clearest signs a battery is on its way out.
Cars log "pending" codes before the check-engine light comes on. Tachwise reads them, and Otto explains each one: what it means and how soon it needs a look.
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.
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 battery rested at 12.6 V overnight. That's normal.
Your car logged a pending code for the downstream oxygen sensor. No light yet. Keep an eye on it; I will too.
The Tachwise device is a working prototype on the bench, not a product yet. The roadmap says where each piece stands.
Start today with a dongle you may already own, or get in line for the device that keeps watching when you're not there.
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.
app.tachwise.com
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.
Free. Takes a minute.
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.
Where each piece actually stands today.
Our firmware, on a development board, has read live data from a real car's OBD-II port. The companion app runs against a simulator.
The app at app.tachwise.com connects to Bluetooth ELM327 dongles in Chrome. Early, and we're learning which dongles behave.
The board that plugs into the port and watches the battery while the car is parked. Next milestone: working in a real car, overnight.
Only once the board works in a car. Until then the waitlist is free and we take no money.
A small production run and radio certification (FCC in the US, ISED in Canada). The price gets set when those costs are known.
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.
No date until we can keep it. The waitlist hears first.
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.
Safari on iPhone and iPad doesn't support Web Bluetooth, which is how a web page talks to a dongle. iPhone support comes with the native Tachwise app. Third-party browsers such as Bluefy add Web Bluetooth, but we haven't tested them.
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.
The app beta is free. For the device, the plan is a one-time price with no monthly fee for what it does. We haven't set a price, and we won't take any money until the device works in a car.
When it's ready. The waitlist hears first.
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.
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.
Join the free waitlist for the Tachwise device. No payment, no deposit. Tell us what you drive so we test on the cars people actually own.