# OTR Diagnostics vs ZDOBD

The clearest difference is review sentiment: OTR Diagnostics at 55% against ZDOBD's 0%. OTR Diagnostics also leads on rating (4.0 vs 2.0) and ratings volume (99 vs 4). ZDOBD's advantage is iOS requirement (15.6 vs 17.6). On price, ads, in-app purchases and monetization model there is nothing between them.

Both are free to download. Neither carries in-app purchases, so what you see is what you pay.

OTR Diagnostics holds the better App Store score, 4.0 against 2.0. That said, the two scores are not equally well evidenced: OTR Diagnostics has 99 ratings behind it against 4, so its average is the more settled of the two. Written reviews point the same way: 55% of OTR Diagnostics's written reviews are positive against 0% of ZDOBD's.

OTR Diagnostics ships an update fortnightly, ZDOBD monthly. The most recent releases landed on September 23, 2026 and September 8, 2026 respectively.

## The numbers

| Metric | OTR Diagnostics | ZDOBD |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[4.0 (99 ratings)](https://appshunter.io/ios/app/otr-diagnostics/id1508165885/reviews)** | [2.0 (4 ratings)](https://appshunter.io/ios/app/zdobd/id6449920963/reviews) |
| Number of ratings | **99** | 4 |
| Positive reviews | **55.2% of reviews** | 0.0% of reviews |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | **Fortnightly** | Monthly |
| Monetization | Free with in-app purchases | Free with in-app purchases |
| Size | 266 MB | 22 MB |
| Requires iOS | 17.6 | **15.6** |
| Devices | iPhone, iPad | iPhone, iPod |
| Age rating | 4+ | 4+ |
| Developer | [OTR Performance](https://appshunter.io/developer/1508165884) | [深圳市正德友邦科技有限公司](https://appshunter.io/developer/1691030696) |

## What reviewers say

### OTR Diagnostics

[App page](https://appshunter.io/ios/app/otr-diagnostics/id1508165885)

This app helps heavy-duty truck owners diagnose and resolve common issues like fault codes, regen problems, and derates. It provides plain-language explanations of error codes, allows for bi-directional commands to fix issues, and monitors live truck data to prevent downtime.

**Highlights:** AI-powered fault code explanation, Bi-directional commands for repairs, Reset active/inactive fault codes, Run forced DPF/SCR regens, Live data monitoring, Fault code history tracking

**Features:** macOS Compatibility, Vision Pro support

**In-app purchases:** none

**What reviewers like**

- 💰 Saves money on repairs
- 🛠️ Clears fault codes
- 🔄 Performs forced regens
- ✅ Works with various engines
- 👍 Easy to use

**What reviewers complain about**

- 💸 Overpriced
- 🐛 Buggy and unstable app
- 🔌 Frequent Bluetooth disconnects
- 📉 Updates cause problems
- ❌ Some features disappeared after updates

**Reported bugs**

- App constantly disconnects from device
- Generic code option disappeared
- Forced regen is no longer consistent
- AI assistant not working
- App asks to do things not available in app

**Requested features**

- Remember email address for login
- Allow offline functionality without data connection
- Add option to change speed
- More detailed diagnostic information
- Allow basic subscription to work on multiple VINs


### ZDOBD

[App page](https://appshunter.io/ios/app/zdobd/id6449920963)

This diagnostic tool connects to portable diesel vehicle devices via Bluetooth to perform comprehensive vehicle checks. It allows users to view ECU information, diagnose and clear faults, monitor real-time data, and conduct specific tests like DPF regeneration.

**Highlights:** Bluetooth connectivity, ECU version information, Vehicle fault diagnosis and clearing, Real-time data flow monitoring, DPF regeneration, SCR testing

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is OTR Diagnostics free?

OTR Diagnostics is free to download, with no in-app purchases.

### Is ZDOBD free?

ZDOBD is free to download, with no in-app purchases.

### Which has better reviews, OTR Diagnostics or ZDOBD?

OTR Diagnostics is rated higher. OTR Diagnostics averages 4.0 out of 5 from 99 ratings, while ZDOBD averages 2.0 from 4 ratings.

### Do OTR Diagnostics or ZDOBD have ads?

Neither OTR Diagnostics nor ZDOBD shows ads.

### Which is updated more often, OTR Diagnostics or ZDOBD?

OTR Diagnostics ships an update fortnightly, and ZDOBD monthly. Most recently, OTR Diagnostics was updated on September 23, 2026 and ZDOBD on September 8, 2026.

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*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*