# OTR Diagnostics vs Circle Fuel

The clearest difference is update cadence: OTR Diagnostics at fortnightly against Circle Fuel's monthly. Circle Fuel's advantage is iOS requirement (14.0 vs 17.6). On price, ads, in-app purchases and device support 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 ships an update fortnightly, Circle Fuel monthly. The most recent releases landed on October 15, 2026 and October 7, 2026 respectively.

## The numbers

| Metric | OTR Diagnostics | Circle Fuel |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[4.0 (99 ratings)](https://appshunter.io/ios/app/otr-diagnostics/id1508165885/reviews)** | — |
| Number of ratings | **99** | — |
| Positive reviews | 55.2% of reviews | — |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | **Fortnightly** | Monthly |
| Monetization | Free with in-app purchases | — |
| Size | 267 MB | 38 MB |
| Requires iOS | 17.6 | **14.0** |
| Devices | iPhone, iPad | **iPhone, iPad, iPod** |
| Age rating | 4+ | 4+ |
| Developer | [OTR Performance](https://appshunter.io/developer/1508165884) | [Circle 5 Corporation](https://appshunter.io/developer/1711072111) |

## 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


### Circle Fuel

[App page](https://appshunter.io/ios/app/circle-fuel/id6468963879)

**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 Circle Fuel free?

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

### Do OTR Diagnostics or Circle Fuel have ads?

Neither OTR Diagnostics nor Circle Fuel shows ads.

### Which is updated more often, OTR Diagnostics or Circle Fuel?

OTR Diagnostics ships an update fortnightly, and Circle Fuel monthly. Most recently, OTR Diagnostics was updated on October 15, 2026 and Circle Fuel on October 7, 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.*