Comparison

OBD2 Logger vs Diagnose AI

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

OBD2 Logger

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OBD2 Logger turns your iPhone into a precision data logger for any modern car. Plug a Bluetooth ELM327 adapter into your vehicle's OBD2 port, pair it once, and stream live engine, hybrid, battery, and emissions data straight into per-session CSV files on your phone. No accounts. No cloud. No analytics. Your driving data never leaves your device. LIVE READOUT • 40+ standard SAE J1979 PIDs, automatically discovered from your car: RPM, vehicle speed, coolant temp, throttle, MAF, intake MAP, fuel trims, catalyst temperatures, and more. • Manufacturer-specific Mode 21 PIDs on profiled vehicles — including HV pack voltage, MG1/MG2 motor torque, and battery cell-block temperatures on Toyota/Lexus hybrids. • Values grouped by category (Engine, Hybrid, Battery, Emissions, Diagnostics) and updated every second. • One CSV per logging session, written into the app's Files container — open it in Numbers, Excel, pandas, DuckDB, or any other tool with no preprocessing. • Wide-table format: ISO-8601 timestamps, one column per active PID, blank cells where the ECU returned no data (no spurious forward-fill). • Smart-stop after extended idle so you don't end up with a tail of empty rows when you forget to tap Stop. WORKS IN THE BACKGROUND • Keeps logging while you drive with Maps in the foreground or the screen off, using Apple's standard background location mode for trip-tracking apps. The system location indicator is shown the entire time. We don't store your location. VEHICLE PROFILES • Ships with three profiles: a generic Mode-01 fallback, a Toyota hybrid family profile, and a 2020 Lexus RX 450h/450hL profile validated against a real vehicle. • VIN auto-read on connect; year, make, model, and trim pre-filled from NHTSA's free public vPIC API. • Import any third-party profile JSON to add coverage for your car. The format is documented and human-readable. DON'T HAVE AN ADAPTER YET? • Tap "Try demo mode" on the second onboarding step to explore the app end-to-end with synthetic data — no hardware required. WHAT YOU NEED • Any Bluetooth Low Energy ELM327 adapter (Veepeak OBDCheck BLE+, vLinker MC+, OBDLink, etc. — most BLE clones work). USB-only and Wi-Fi-only adapters are NOT supported. • A car with an OBD2 port (1996+ in the US, 2001+ in the EU). PRIVACY • Nothing is collected, transmitted, or stored on our servers — we don't have servers. The only outbound call the app ever makes is one VIN decode per vehicle to NHTSA's vPIC API. • Your CSVs and vehicle records live in the app's Files container, accessible to you in the iOS Files app under On My iPhone → OBD2 Logger. • Open source: github.com/NathanNam/obd2-logger

About

Diagnose AI

This app transforms your phone into an automotive health assistant. It connects to your car's OBD-II system via Bluetooth to translate fault codes into plain English, offering AI-powered diagnostics and DIY action plans. Manage multiple vehicles and review scan history for informed repairs.

Highlights
  • AI-powered plain-English diagnostics
  • One-tap Bluetooth OBD-II scanning
  • DIY action plans and guidance
  • Multi-vehicle garage management
  • Full scan history
  • Premium dark automotive interface
Features
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Know what's your car is telling you Bruh.. and what to check before you buy one. Diagnose AI turns OBD-II fault codes, warning lights, recall information, and guided vehicle checks into clear findings you can act on. FOR YOUR CAR • Connect a compatible Bluetooth OBD-II adapter • Understand stored and pending trouble codes in plain English • See how urgent a problem may be and what to check next • Save your vehicles and scan history • Ask follow-up questions about a completed scan BEFORE YOU BUY • Enter a VIN to review available recall campaigns • Follow a guided visual inspection • Add supported OBD-II findings when available • See what needs attention, what needs review, and what was not checked • Export a Buyer Report to keep or share No adapter yet? No Worries Try the demo scan and explore the experience without connecting to a vehicle. Diagnose AI provides informational guidance and does not replace a qualified mechanic, professional pre-purchase inspection, official recall-repair confirmation, or vehicle history report. Vehicle and adapter support vary. Terms of Use (EULA): https://www.apple.com/legal/internet-services/itunes/dev/stdeula/

Screenshots

OBD2 Logger4 screens
Diagnose AI4 screens

Verdict

The call

The clearest difference is in-app purchases: OBD2 Logger at none against Diagnose AI's 2. OBD2 Logger also leads on update cadence (every 6 weeks vs every 4 months). Diagnose AI's advantage is device support (3 vs 1) and iOS requirement (15.0 vs 17.0). On price and ads there is nothing between them.

Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS

CostPrice · In-app purchases · Ads · Monetization

Both are free to download. Diagnose AI sells 2 in-app purchases, starting at $2.99 per month. OBD2 Logger asks for nothing beyond the download.

UpkeepUpdate frequency

OBD2 Logger ships an update every 6 weeks, Diagnose AI every 4 months. The most recent releases landed on October 4, 2026 and October 23, 2026 respectively.

Scorecard4 real differences · 5 level
OBD2 Logger versus Diagnose AI: the parameters behind the verdict, then further details
ParameterOBD2 LoggerDiagnose AI
PriceFreeFree
Rating—5.0 (1 ratings) — better
Number of ratings—1 — better
Update frequencyEvery 6 weeks — betterEvery 4 months
AdsNoNo
In-app purchasesNo — betterYes
Monetization—Freemium
DevicesiPhoneiPhone, iPad, iPod — better
Requires iOS17.015.0 — better
Further details — not scored
Size3 MB44 MB
Age rating4+4+
DeveloperDaehyun NamShivansh Chhhabra

In-app purchases

None

OBD2 Logger

No in-app purchases

2 purchases

Diagnose AI

Subscriptions2
  • Pro Monthly$2.991 Month
  • Pro Yearly$19.991 Year

Questions

Is OBD2 Logger free?
OBD2 Logger is free to download, with no in-app purchases.
Is Diagnose AI free?
Diagnose AI is free to download, with in-app purchases available.
Do OBD2 Logger or Diagnose AI have ads?
Neither OBD2 Logger nor Diagnose AI shows ads.
Which is updated more often, OBD2 Logger or Diagnose AI?
OBD2 Logger ships an update every 6 weeks, and Diagnose AI every 4 months. Most recently, OBD2 Logger was updated on October 4, 2026 and Diagnose AI on October 23, 2026.

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