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 and 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: Google Play (Android) or the App Store (iOS, where it's listed as "scan my T3SLA"), a one-time purchase of ~$10. Licenses are separate: buying on Android doesn't carry over to iPhone or the other way round (developer FAQ). If Google Play says the app isn't available, see the section below. The alternative is TM-Spy (similar features).
2. An adapter cable to the CAN connector: a different one for each model and build date (table below). The standard OBD-II port under the dash, if the car has one at all, won't work: on a Tesla it only provides +12 V and the VIN.
3. An OBD-II dongle over Bluetooth or Wi-Fi. On Android almost any decent ELM327-compatible dongle works; on iPhone only a few models do (below).

Total kit: from ~$45 on Android with an inexpensive ELM327; ~$85-140 on iPhone with a vLinker FS; ~$180-200 with an OBDLink MX+.

Where to download Scan My Tesla if Google Play says it's not available in your country

There are two official sources: Google Play and the App Store. scanmytesla.com only links to those stores; the developer offers no separate APK. If your Google account is registered in a country where Play sells the app, just buy it there. The "not available" message is a typical problem for accounts registered in Belarus, so the experience below comes from there; links like #426575 point to messages in the TESLA Belarus owners' chat.

• iPhone. The Belarusian App Store sells the app without changing region (#426575, #426579). Search for "scan my T3SLA". The catch is the hardware: not every dongle works with an iPhone, and a cheap ELM327 won't connect (details below).
• Android. With a Belarusian Google Play account the paid app can't be downloaded or bought (#426602). A VPN doesn't help: the store looks at the account's country, not your IP (#1375).

What owners do:

1. Buy it on an iPhone if there's one in the family, and get a compatible dongle for it.
2. Set up a separate Google account with another country, for example during a trip to Poland or Lithuania. Under Google's rules you can only set the Play country while physically in that country and with a payment card from it, and the next change is possible no sooner than 90 days later (Google help). When you're abroad, Play offers to switch the region of your main account, but you can't switch it back quickly, so the chat's advice is to create a second account and leave the main one alone (#359677, #359678).

Why not install a cracked APK from chat files, forums or "mirrors":

• Scan My Tesla connects to the car's CAN bus through the dongle, and the dongle can send messages to the bus, not only read them. A repackaged app can send anything there, and garbage on the CAN bus can seriously harm the car (#426549).
• Nobody has checked an APK from an unofficial source: it may carry a trojan, and the app needs access to the phone's Bluetooth and location.
• Cracked builds are usually old versions: no support for newer cars and firmware, no updates, no refunds.
• The license is a one-time ~$10, cheaper than the cable.

Which cable and adapter you need, by model and year

Pick the cable by model and build date (it's on the sticker in the driver's door opening). Even a Model 3 can't be read without the cable (#237597), and a cable for one model doesn't fit another: a 2019 Model S can't be read with the 26-pin Model 3 cable (#469882).

Prices are from the European sellers that the Scan My Tesla site recommends, as of October 2026. Such cables are cheaper on AliExpress, but check the connector against the photos: if your build date is close to a generation change, the developer explicitly advises comparing your plugs with the pictures in the store.

The 26-pin and 20-pin cables are splitters: you unclip the factory connector and insert the cable between the two halves. Before that, turn off Sentry Mode, lock the car and let it go to sleep: cable sellers recommend waiting about 10 minutes until the CAN buses power down. The dongle doesn't depend on the model; you choose it for your phone.

iPhone or Android: which dongle works

The difference is the Bluetooth type. The Android version works with any ELM327-compatible Bluetooth Classic adapter that supports CAN. iOS doesn't let apps use ordinary Classic adapters, so the iPhone version supports only specific models: OBDLink MX+, vLinker FS and S3XY Commander (the list from the App Store description), plus the CANserver and S3XY Buttons Wi-Fi adapters. Generic Wi-Fi ELM327 dongles aren't on the compatibility list.

From the chat:

• A cheap ELM327 doesn't work with an iPhone (#426579), while a vLinker FS from AliExpress and an OBDLink MX+ do connect (#335538, #497520).
• On Android even a cheap ELM327 reads a Tesla (#426545); data just comes in more slowly (#30943). Get the two-board v1.5 version with the PIC18F25K80 chip (#426596): one owner's single-board ELM327 v2.0 read another car but not the Tesla (#476672).
• Don't leave the dongle in the car permanently. A stranger can connect to a cheap ELM327 with its default password and push garbage onto the CAN bus that can disable the car. The splitter cable itself can stay; unplug the dongle (#426549, #426555).

Key readings (and what they mean)

How to check SOH

SOH (State of Health) comes from one formula:

SOH = Nominal Full Pack ÷ Full Pack When New × 100%

• Nominal Full Pack is how much energy the pack holds now, as estimated by the BMS (service signal BMS_nominalFullPackEnergyRemaining).
• Full Pack When New is the pack's factory constant (BMS_beginningOfLifePackEnergy). Scan My Tesla shows it only for Model 3/Y.
• The BMS reports both numbers including the buffer, so the buffer doesn't skew the result (#157776, #334554).

Don't look for a ready-made degradation percentage in Scan My Tesla: the developer removed that calculation from the app as inaccurate (FAQ). Do the math yourself.

Example from the chat: a 2023 Model Y Performance with 30,000 km; the owner posted the BMS service signal values (#438142, #438143).

82.1 kWh is the factory constant of the 82 kWh Panasonic pack; for comparison, pre-refresh US Model 3 Long Range cars show 77.8 (#157798). That matches the 82 kWh capacity listed in the Akkuwiki. What the example shows: 83% at 30,000 km is below the "≥85% up to ~150,000 km" benchmark, even though cell balance is perfect. Capacity and imbalance are independent readings, so check both. For this pack's weak spots, see the article on 82 kWh Panasonic imbalance.

Pitfalls:

• Full Pack When New shows 0 or 0.1. That's a read glitch, seen after the 2025.32 update (#310951, #311524, #426511). Take your pack's factory capacity from the battery chemistry guide.
• LFP. The BMS estimate on LFP is accurate only after a recent charge to 100% (Tesla already recommends charging LFP to 100% once a week). If the car spent a month between 50% and 70%, the figure can drift by a few percent.
• Model S/X. The app doesn't show Full Pack When New, so compare Nominal Full Pack with the pack's factory capacity, e.g. ~100 kWh for Palladium.
• One reading isn't a verdict. The BMS estimate wanders by a couple of percent. If the number is borderline, the Battery Test in Service Mode gives a more precise result.

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

Scan My Tesla is the cheapest way to see the battery cell by cell. The other tools cover other jobs: alerts and service routines, a certificate for resale, long-term history or the factory spec.

• Service Mode: how to enter it is covered in the certificates & Service Mode article. Some alerts aren't visible there: they're hidden Service Mode Plus alerts, and Service Mode Plus is unlocked with Toolbox (#403188, #381804).
• Toolbox 3 is sold officially at toolbox.tesla.com. Before the 2025 price cut the subscription cost $500 a month and $3,000 a year, so the chat treated Toolbox as a workshop tool (#27492); a $75 one-day pass is now within reach of a private owner.
• Don't buy a "cheap Toolbox" through middlemen, proxy services or cracked copies: the car connects to someone else's account and server, and you have no control over what's done to it there.
• TeslaMate is for long-term history rather than a one-off check; what happened to it after the Tesla API changes is covered separately.
• Aviloo is handy for resale: the buyer sees a certificate from an independent company.

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
• Tesla battery (BMS) error codes decoded: what the alerts in Service Mode mean
• Battery Test via Service Mode: a precise capacity reading when SOH is borderline
• TeslaMate and the paid Tesla API: a history logger on your own server