Comparison

J1939OBD vs DiagNova

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

Head to head
About

J1939OBD

Features
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A diagnostic app for industrial and commercial vehicle engines using the J1939 CAN protocol. The app supports the following functions: - Display the active error codes - Display the passive error codes - Delete the error codes - Display of engine measured values - Information about the status DPF - Information about the SCR system - Information about fuel consumption - Engine information - Terminal mode To connect to the engine you need an EML327 compatible Wifi OBD interface as of V1.4 and a connection cable from the diagnostic connector to OBD. Various manufacturers offer corresponding cables, as well as a well-known engine manufacturer from Cologne, who distributes a corresponding adapter cable via his dealer network. Visit my homepage for further informations. An EML327 Wifi interface is offered on known Internet platforms.

About

DiagNova

Features
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DiagNova turns any ELM327-compatible OBD2 adapter into a guided diagnostic assistant. Most scanners stop at "here are your codes." DiagNova tells you the likely cause, whether the car is safe to drive, and walks you through the fix β€” using your car's own live data. WHY DIAGNOVA IS DIFFERENT β€’ Guided live diagnosis β€” A decision-tree engine reads your live sensor data (RPM, fuel trims, MAF, O2, coolant) and ranks the most likely causes with confidence scores. No more swapping parts on a guess. β€’ Safe-to-Drive verdict β€” A clear, conservative call β€” stop now, drive with caution, or you're OK β€” based on misfire severity, temperature, battery and code criticality. β€’ Pre-MIL prediction β€” Reads Mode 06 on-board monitor trends to warn you before the check-engine light actually comes on. β€’ Second-Opinion certificate β€” Export a shareable PDF that proves the diagnosis with the live data behind it. Bring it to the mechanic so you don't get upsold. β€’ Multi-code root-cause correlation β€” When several codes fire together, DiagNova spots the single underlying fault that explains them. β€’ Plain-language symptom search β€” Describe the problem in your own words and jump straight to the right playbook. EVERYTHING FROM ONE CHEAP ADAPTER β€’ Stored, pending and permanent DTCs (Mode 03 / 07 / 0A). β€’ Mode 06 on-board monitor test results and Mode 09 vehicle info (CALID / CVN / IUMPR). β€’ Freeze-frame analysis β€” ranks causes from the snapshot saved when the fault triggered, no driving needed. β€’ Per-cylinder misfire localization. β€’ 97 DTC playbooks and 22 repair playbooks β€” and it learns: your repair outcomes refine the next diagnosis. EVERYDAY DASHBOARD β€’ Live vitals strip β€” coolant, battery, fuel level, intake air, in real time. β€’ Last-scan summary and session compare (DTC diff + PID trend charts). β€’ Threshold alerts (coolant, fuel trim, battery) and readiness monitors for inspection. β€’ VIN decoder, trip fuel-cost tracker, maintenance log with service reminders. β€’ Adapter health check β€” detects common ELM327 clones and connection quality. β€’ PDF / CSV export. FREE, PRIVATE, LOCAL-FIRST β€’ 100% free β€” no subscription, no ads. β€’ No accounts, no cloud, no tracking, no analytics. β€’ All data stays on your device in a local SQLite database. Anything shared is strictly opt-in. WORKS WITH β€’ Any ELM327-compatible adapter β€” BLE (Bluetooth Low Energy) and WiFi. DISCLAIMER DiagNova is a diagnostic aid, not a replacement for professional service. Always follow your vehicle manufacturer's repair procedures and observe safety warnings.

Screenshots

J1939OBD4 screens
DiagNova4 screens

Verdict

The call

The clearest difference is in-app purchases: DiagNova at none against J1939OBD's 1. On price, ads, device support and iOS requirement there is nothing between them.

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

CostPrice Β· In-app purchases Β· Ads Β· Monetization

Both are free to download. J1939OBD sells 1 one-off in-app purchase. DiagNova asks for nothing beyond the download.

Scorecard1 real difference Β· 5 level
J1939OBD versus DiagNova: the parameters behind the verdict, then further details
ParameterJ1939OBDDiagNova
PriceFreeFree
Update frequencyEvery 41 monthsβ€”
AdsNoNo
In-app purchasesYesNo β€” better
DevicesiPhone, iPodiPhone, iPad, iPod β€” better
Requires iOS12.1 β€” better13.0
Further details β€” not scored
Size14 MB29 MB
Age rating4+4+
DeveloperS.KoepgeKING DROID SRL

In-app purchases

1 purchases

J1939OBD

One-time1
  • Get full access for 1939OBD$3.99
None

DiagNova

No in-app purchases

Questions

Is J1939OBD free?
J1939OBD is free to download, with in-app purchases available.
Is DiagNova free?
DiagNova is free to download, with no in-app purchases.
Do J1939OBD or DiagNova have ads?
Neither J1939OBD nor DiagNova shows ads.

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