# OTR Diagnostics vs Chicago fuel

The clearest difference is update cadence: OTR Diagnostics at fortnightly against Chicago fuel's every 11 months. Chicago 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, Chicago fuel every 11 months. The most recent releases landed on October 29, 2026 and October 14, 2026 respectively.

## The numbers

| Metric | OTR Diagnostics | Chicago 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** | Every 11 months |
| Monetization | Free | — |
| Size | 268 MB | 34 MB |
| Requires iOS | 17.6 | **14.0** |
| Devices | iPhone, iPad | **iPhone, iPad, iPod** |
| Age rating | 4+ | 17+ |
| Developer | [OTR Performance](https://appshunter.io/developer/1508165884) | [Tomas Gintila](https://appshunter.io/developer/1594199960) |

## What reviewers say

### OTR Diagnostics

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

This diagnostic tool helps heavy-duty truck owners understand and resolve fault codes, perform crucial maintenance tasks like regens, and monitor live engine data. It aims to reduce downtime and avoid costly dealer visits by empowering users with detailed insights and control over their vehicle's systems.

**Highlights:** Reset active and inactive fault codes, Perform forced DPF/SCR regens, Understand fault codes in plain language, Monitor live engine data, Track fault code history, Bi-directional commands for repairs

**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


### Chicago fuel

[App page](https://appshunter.io/ios/app/chicago-fuel/id1634815571)

**In-app purchases:** none


## Frequently asked questions

### Is OTR Diagnostics free?

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

### Is Chicago fuel free?

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

### Do OTR Diagnostics or Chicago fuel have ads?

Neither OTR Diagnostics nor Chicago fuel shows ads.

### Which is updated more often, OTR Diagnostics or Chicago fuel?

OTR Diagnostics ships an update fortnightly, and Chicago fuel every 11 months. Most recently, OTR Diagnostics was updated on October 29, 2026 and Chicago fuel on October 14, 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.*