Frequently asked questions

Yes, an OBD-II adapter on the ELM327 chip (Bluetooth Classic SPP) — starts around $10. We do not sell adapters, but we maintain a compatibility list in the docs.

All cars and light commercial vehicles with an OBD-II port — mandatory since 1996 in the US, 2001 in the EU. Heavy trucks on J1939 are on the roadmap.

DTC reads and live telemetry — yes, fully local with the adapter. AI analysis, history sync and cloud reports — internet required.

Reading data (Mode 01, 03, 09) is fully safe — passive queries only. Clearing DTCs (Mode 04) is safe but requires explicit confirmation. We do not perform write operations without certification.

Session data lives in a secured cloud DB, tied to your account. AI analysis uses anonymised readings (no VIN). Full policy — see /privacy.

Yes, any time from your account. Access stays until the end of the paid period. Your subscription renews automatically until you cancel; a receipt is emailed after each charge.

Currently GPT-class for text explanations and proprietary ML models for failure prediction (based on DTC history + telemetry). Specifics in /docs/getting-started.

Yes, OBD-II diagnostics works regardless of fuel type — the diagnostic port and protocols are the same. LPG equipment does not interfere with engine code reading. Specific LPG injector errors are usually not broadcast over standard OBD-II.

Diesel engines are fully supported — OBD-II is a single standard for both petrol and diesel. EGR codes (P0400–P0409), DPF codes (P2002, P242F) and injection system faults are read with standard Mode 03/07/0A queries. No extra adapters needed.

Avoid adapters without a marked chip version, "MINI ELM327 v1.5" units without the actual v1.5 chip, and WiFi-only clones. Signs of a genuine adapter: "ELM327 v1.5" or "v2.1" printed on the case, Bluetooth Classic (SPP), price from $10. Recommended models are listed in the adapter pairing docs.

Car Diagnostics is currently Android 7+ only. An iOS version is on the roadmap but there is no specific timeline. BLE (Bluetooth Low Energy) OBD-II adapters are technically iOS-compatible and widely available, but the Car Diagnostics Android client uses Bluetooth Classic SPP — this is why BLE-only adapters are not supported here.

Free — 1 vehicle. Personal — up to 3 vehicles. Pro — up to 10 vehicles. Fleet — unlimited. Full feature breakdown per plan is on the pricing page.

A "Delete Account" button is in your profile section. After confirmation, all your data — session history, vehicles, payment info — is permanently deleted. The process is irreversible and GDPR-compliant.

PID (Parameter ID) refers to standard OBD-II parameter identifiers such as engine RPM (PID 0C), vehicle speed (PID 0D), and coolant temperature (PID 05). Live telemetry means reading these parameters in real time at up to 5 Hz and plotting graphs on screen.

Yes, Car Diagnostics reads all four code groups: P (powertrain), B (body — airbags, climate), C (chassis — ABS, traction) and U (network — CAN bus). However, not all vehicles expose B/C/U codes over standard OBD-II — this is manufacturer-dependent.

Car Diagnostics is a consumer app for quick diagnostics, not a professional dealer-level scan tool. VCDS and Launch offer deeper ECU access (coding, adaptations) but cost $200–$1000+. Our advantage: AI explanations in plain language, pricing from $0, and compatibility with any $10 ELM327 adapter.

Subscription can be paid via Monobank or PrivatBank. Credit/debit card (Visa/Mastercard) and Google Pay are also available. All prices are in USD, billed monthly.

Hybrids are supported — they have a standard OBD-II port for the internal combustion engine. Electric vehicles (Tesla, Nissan Leaf, etc.) are not supported because their diagnostics use separate, non-OBD-II protocols.

The Fleet plan lets you add unlimited vehicles, create roles (admin, mechanic, driver) and assign per-vehicle access. Pricing is custom — based on fleet size. Contact us through the website form for a quote.

The Free plan gives you unlimited local scans, 1 vehicle, and guest mode. Shows the bare fault code only — no description, severity, or system. Limitations: no cloud history, no AI explanations, no AI reports, no exports, no fleet features. For full AI-assisted diagnostics, we recommend Personal ($4.99/mo).

A large commercial language model accessed through a model-routing abstraction layer, so the provider can be swapped without changing the diagnostic pipeline. Analysis runs across 8 specialized AI agents — one of which is the router that dispatches to the other seven.

Yes — approximately 145,000 DTC codes with expert descriptions, maintained server-side and never bundled into the mobile app. The AI is grounded in this data rather than answering from general knowledge.

Yes — a dedicated retrieval service backed by a vector database with text embeddings. Relevant technical material is retrieved and injected into the model context before it answers. RAG powers the AI chat, failure predictions, DTC analysis and maintenance recommendations.

On top of standard TLS transport, the app establishes an additional application-layer encrypted channel: X25519 ephemeral ECDH key exchange, HKDF-SHA256 key derivation, and AES-256-GCM authenticated encryption. This is transport protection, not end-to-end encryption — the server decrypts data in order to analyse it.