Tesla diagnostic software: Scan My Tesla, OBD adapter & what it shows (2026)

Scan My Tesla is the go-to Tesla diagnostic app: what Tesla hides from the owner, it reads straight off the car's bus. Real battery state, cell imbalance, temperatures, charge efficiency — everything you need to judge a used car or catch a problem early.

What you need to connect

1. The Scan My Tesla app — iOS App Store or Android Google Play, one-time ~$10. Alternative — TM-Spy (similar features).
2. An adapter to the diagnostic port:
   • Model 3 / Y — non-standard port behind the trim at the rear of the center console. 4-pin on Model 3 from April 2019 and all Model Y; earlier Model 3 (2017 – early 2019) use a different connector. Adapter cables come in two versions — "pre-2019" and "2019+" — pick by build date ($20-40), otherwise it won't connect.
   • Model S / X — diagnostic access differs (behind the center console / under trim); match the adapter to your year.
3. An OBD-II dongle over Bluetooth/Wi-Fi. Working ones: OBDLink MX+ / LX, Vgate iCar Pro. Cheap ELM327 clones often choke on Tesla's data — get a proven one.

Total kit — roughly $40-120 depending on the dongle. Buy once, use forever.

Key readings (and what they mean)

How to read it when buying used

The most accurate way to avoid a dead battery or a rolled-back odometer:

• SOH ≥ 85% for mileage up to ~150k km. If SOH is well below the claimed mileage, the odometer is probably rolled back (see the used-buying checklist).
• Cell imbalance: <30 mV for NMC/NCA, <10 mV for LFP (LFP is stricter). Big imbalance on NCA 82 kWh Panasonic is a known issue.
• Compare Nominal Full Pack vs Full Pack When New to identify the pack and its real degradation. Cross-check with the battery chemistry guide.

Alternatives to Scan My Tesla

• Service Mode — built-in, no hardware: the Battery section shows configuration and basic data. Since firmware 2025.8 Tesla also has its own battery health test. Less detail, but free (how to enter — in the certificates & Service Mode article).
• TM-Spy — a Scan My Tesla analog.
• TeslaMate — continuous logging (needs a server/Raspberry Pi), for long history rather than a one-off check.
• Aviloo — a paid certified battery-health test (issues a report/certificate), handy for resale.

When self-diagnostics isn't enough

Scan My Tesla covers most everyday questions, but some systems it doesn't see at all or sees only partially. A professional diagnostic session additionally covers:

• insulation resistance of the high-voltage system — an early indicator of moisture and insulation degradation;
• the condition of the charge port contactor;
• the air suspension — bags and compressor (relevant for S/X);
• the correctness of the inverter's control signals;
• real-time analysis under load — cell balance deviation while driving, elevated AC compressor current, drop in regen efficiency.

Minsk reference prices, BYN (one shop's figures, not the market): basic diagnostics, 30–40 minutes — from 80 BYN; an extended session with real-time parameters, 1–1.5 hours — from 150 BYN; with a test drive, up to 2 hours — from 200 BYN.

A sensible cadence for a professional session is once a year or every 20,000 km, and it's a must before buying used and after any accident.

Source: tsk.by

Related articles

• Used Tesla buying checklist — where to plug Scan My Tesla in and what to measure
• Battery chemistry guide (NCA, NMC, LFP, 4680) — identify the pack by its numbers
• 82 kWh Panasonic module imbalance — the main thing diagnostics catches
• Module/cell replacement — if diagnostics found a problem