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BETSY FAQ

What is BETSY?

BETSY is a free, open-source Android app that reads hybrid battery data, diagnostic trouble codes and Toyota INF/detail sub-codes through an ELM327-compatible adapter. The goal is to give Prius owners useful diagnostic information without requiring dealer software, a special diagnostic cable or a laptop.

Which cars are supported?

• Prius 2004–2009 (Gen 2): confirmed on a stock US-market 2009 car.
• Prius 2010–2015 (Gen 3): implemented, but not yet verified on a real Gen 3.
• Prius 2001–2003 and 2016 onward: recognised but not supported by the current build.

Other Toyota or Lexus hybrids using the same protocol may work, but they have not been validated.

What hardware do I need?

An Android phone running Android 8.0 or newer and an ELM327-compatible Bluetooth or Wi-Fi adapter. Development and on-car testing used an inexpensive Bluetooth clone.

Does BETSY read INF/detail sub-codes?

Yes, on the confirmed Gen 2 path. BETSY reads all five diagnostic detail pages from the hybrid-control ECU and reports the transmitted three-digit INF value.

Version 0.0.3 includes plain-language explanations for 204 exact DTC/INF combinations. That covers approximately 69% of the known Gen 2 pair inventory. Explanation coverage will grow as more source material and real-car captures become available.

What happens when BETSY encounters a sub-code it cannot explain?

BETSY still displays the main DTC and the raw INF value. It leaves the explanation unresolved rather than borrowing a meaning from another code or guessing.

The scan is therefore still useful, and sharing the raw capture can help add a verified explanation in a future build.

Can BETSY handle more than one fault at a time?

Yes. It matches each INF value only against documented parent DTC/INF pairs reported by the hybrid controller. Equivalent mappings can share an explanation; genuinely ambiguous combinations remain unresolved.

Will BETSY change anything on my car?

No. The current build is read-only. It does not clear trouble codes, run actuator tests or write to an ECU. Code clearing may be considered in a future build, but it is deliberately not implemented now because clearing a fault can destroy useful diagnostic and freeze-frame data.

What is included when I share a diagnostic capture?

A shared capture can include the app version, detected vehicle layout, adapter model, diagnostic trouble codes, raw diagnostic responses and a short diagnostic log. BETSY removes vehicle-identifying information before submission and does not include the VIN, location, or a phone/account identifier.

The app shows the consent details before anything is submitted.

Where can I download BETSY?

Download the latest APK from the BETSY releases page. Android will warn about installing an app from outside the Play Store; that is expected for a sideloaded build.

How can I help?

Try BETSY on a Gen 2 or Gen 3 Prius with an active or stored fault and share the resulting capture. Unknown and unusual faults are especially valuable because the raw data can extend both vehicle support and the explanation catalog.

For bugs, questions or contributions, open an issue.