Telltale — Live Car Telemetry

Read your car through an ELM327 adapter: live RPM, speed, coolant, load and intake temperature, fault codes, and the full vehicle state recorded at the moment a fault occurred.

This app is organised around one sentence:

A plausible wrong number is worse than no number.

Diagnostic results get acted on with a wrench. A −40 °C coolant reading gets a sensor replaced; "no fault codes" sends someone away in a car that still has a problem. So every rule here exists to make uncertainty look like uncertainty, instead of like an answer.

〇What it does

• Six hand-drawn gauges in five skins — not just recoloured: the dial shape, needle and motion differ. Both dark and light backgrounds
• Fault codes: Mode 03 stored, Mode 07 pending, Mode 0A permanent, each labelled with the controller that reported it
• Freeze frame: the vehicle state at the moment the fault was confirmed — RPM, coolant, load, fuel trim. It is the only record in the app of conditions while the fault was happening, and clearing the codes destroys it permanently, so the app asks first
• Emissions readiness: see which monitors have completed before an inspection
• Derived values: power, torque, fuel use, air flow. Generic OBD still works with no VIN and no catalog match; estimates are labelled with the formula and the vehicle assumptions they rest on, and are not measurements
• Custom PIDs: write your own formulas, with CSV import and export
• Acceleration test: timed from a standstill to a target speed
• Diagnostic transcript: every byte exchanged with the adapter is kept and can be exported when a connection fails; recording and export keep their status labels
• English, Traditional Chinese and German, switchable on the connect screen and in Settings, or set to follow the system. A few messages are still Traditional Chinese only

〇Four ways to connect

Bluetooth Classic (RFCOMM/SPP), Bluetooth LE (GATT UART), Wi-Fi (TCP), and a built-in Demo simulator — every screen works with no adapter and no vehicle.

〇What it deliberately refuses to do

• It does not turn "the controllers that answered reported no codes" into "this vehicle has no fault codes"
• When two controllers answer the same question differently, it uses neither — picking one is picking at random
• Unverified readings stay usable and stay labelled with their source and state (unverified / estimated / anomalous); a malformed packet never becomes a plausible-looking number
• No ads, no tracking, no personal data collected

〇Open source

The source is on GitLab under GPL-3.0, and you can build it yourself:
https://gitlab.com/aa22396584/telltale

The paid Play edition has exactly the same features — nothing is held back. It is for people who would rather not build it themselves, and for those willing to support continued development.

F-Droid, GitLab release and Google Play builds use three different signing keys. They cannot update each other in place; that is intentional.

〇What you need

An ELM327 OBD2 adapter (Bluetooth or Wi-Fi) and an OBD2-compliant vehicle. It still connects and reads without a catalog entry or vehicle data.

〇Notice

This app is not affiliated with, endorsed by, or derived from Ian Hawkins' Torque or Torque Pro. The OBD2 implementation follows public standards including SAE J1979 and the ELM327 datasheet.

Recent changes:
Larger Android Auto gauges with day/night colors. Speed now displays as an integer. Tap a dashboard gauge’s info icon to understand its status. Very-low-priority PIDs stay fresh between normal updates. Vehicles without 7E8 learn support from all responders; unsupported PIDs stop polling. Tested with Demo/DHU only; reporter vehicles, adapters and real head units remain unverified.