# Gretio — The Missing Pocket Scan Tool

> Advanced GM vehicle diagnostics and service tool with OBDLINK MX+ integration. (iPhone/iPad app by Surreal Development LLC.)

- Source: https://appshunter.io/ios/app/gretio/id1498320180 (this page in markdown: same URL + `.md`)
- Developer: [Surreal Development LLC](https://appshunter.io/developer/1498320179)
- Category: Productivity, Utilities
- Price: Free with in-app purchases
- Rating: 3.91/5 from 22 App Store ratings · 18 written reviews indexed
- Age rating: 4+
- Requires: iOS 18.0 · 40 MB
- Languages: English
- Released: 2021-07-02
- Data updated: 2026-08-15
- Monetization: free with in-app purchases
- User reviews in markdown: https://appshunter.io/ios/app/gretio/id1498320180/reviews.md

## What is Gretio?

Use Gretio with an OBDLINK MX+ to perform advanced diagnostic functions on your diesel, gas, electric, or hybrid vehicle.

Analyze thousands of different data points at high speeds.
Look up diagnostic trouble codes for all modules including the Engine Control Module, Chassis Control Module, Drive Motor Control Modules, Battery Energy Control modules, Body Control Module, Radio, and many more.
Perform advanced service functions such as diesel particulate filter service regenerations, selective catalytic reduction tests, power relay tests, and even program some features.

Gretio is an advanced tool made for the DIY market. All procedures must be used in accordance with the vehicle's service manual or other OEM approved literature.

Gretio is made exclusively for General Motors vehicles. Additional models will be supported in the future.

## Key features

- Advanced diagnostic functions
- Analyze thousands of data points
- Look up diagnostic trouble codes
- Perform advanced service functions
- Exclusive for General Motors vehicles

## Pricing and in-app purchases

Base price: Free.

**Subscriptions**

| Subscription | Price | Period |
| --- | --- | --- |
| Gretio All Access | $19.99 | per year |

**One-time purchases**

| Purchase | Price | Type |
| --- | --- | --- |
| Gretio RPO Pack 1 | $29.99 | one-time |
| Gretio RPO Pack 2 | $29.99 | one-time |
| RPO Pack 3 | $29.99 | one-time |


## Recent user reviews (10 of 18)

All indexed reviews: https://appshunter.io/ios/app/gretio/id1498320180/reviews.md

### 5/5 — Phenomenal for 16 LML Duramax

*2025-10-08*

I bought the lml rpo pack and have been using gretio with the obdlink mx+ to work on my 2016 Chevrolet Duramax LML and it’s been great. From the egr cooler bypass valve to the reductsnt tank heaters to the NOX2 sensor, this has proven to be invaluable and helped save me thousands of dollars doing things myself. Highly recommended!

### 3/5 — Connection problems with obdlink mx+

*2025-07-11*

I bought the lml rpo pack and have been using gretio with the obdlink mx+ to monitor my 2016 lml duramax while driving. There are connection problems. I connect the obdlink mx+ to my iphone 11 pro running iOS 18.5, but when i then try to connect gretio, it doesn’t connect and the obdlink also disconnects and then has problems reconnecting. Ultimately , after factory resetting the obdlink and reconnecting from scratch, gretio will connect. But not always. Sometimes gretio still won’t connect and still disconnects the obdlink. Very frustrating. Sometimes it works and sometimes not. Something is not right.

### 5/5 — Extremely powerful for the cost

*2025-06-01*

Worth every penny considering a dedicated scan tool with the same capabilities would cost you over a thousand bucks. I downloaded this app just for the service bay test function to clear the dreaded “poor DEF quality” countdown to limp mode on my diesel Colorado. Highly recommend!

### 5/5 — Incredibly Capable

*2024-12-20*

Though not super slick and sometimes crashes, this app is an absolute powerhouse for dealing with complex, intermittent sensor issues in modern diesels. Without question, I would not have been able to resolve my issue without it. Be sure to track down their troubleshooting guide if you are chasing diesel emissions issues. The guide brings context to the data and maps a path to resolution.

**Developer response:** Thanks for the feedback, and I am glad it fixed your issues :)

### 5/5 — 2017 GMC Canyon with 19 miles before limp

*2024-11-13*

Found a forum where the author said he had a truck like ours with similar issues, and that he had an app for that! Bought the OBD link mentioned for $138 on Amazon and paid the $20 for the app. We also replaced the Nox sensor 1 to start fresh(er). Hooked the OBDlink up to Bluetooth, used the Gretio app to run the DPF Service Regen, (so cool to watch the soot percentage come down)then the DPF Reset, then the Reductant System Malfunction Warning Service Bay Test and all is right in the world again.

### 5/5 — Best $20 I’ve ever spent!

*2024-10-23*

Look, I’m a Soldier stationed overseas in Italy, NO GMC dealerships here. I got the dreaded “Exhaust Fluid Quality Poor” message in my 2017 Canyon, and I was freaking out, because I still have 3 years left in Italy. I swapped both NOx sensors and the speed limit warning did not go away, I kept searching and I came across the OBDLink MX+ and the Gretio App, I ran the Reductant System Malfunction Warning Service Bay Test through the Gretio App and BOOM! Problem solved! I’ll keep paying the yearly subscription out of gratitude for this fantastic app! Thank you!

### 4/5 — GM ultimate app!

*2024-10-20*

Many options and deep diagnostics on every module for these newer models! Great addition for a technician or at home mod fanatic!

### 5/5 — GM Diesel Enthusiast Must Have

*2024-07-14*

The combination of this app and its concise diesel emission trouble shooting guide are invaluable! Using them, along with OBDlink MX+, I was able to resolve the “Exhaust Fluid Quailty Poor” issue that was on the verge of bricking my LWN diesel. Being able to conduct diagnostic tests to resolve diesel emission issues removes the haunting fear of diesel ownership. I give thanks to the developer for sharing his skill and automotive passion!

### 1/5 — Connectivity

*2024-07-10*

Could you please fix the issue of not connecting to the OBD Bluetooth device. It shouldn’t take 10 minutes and 87 attempts

### 5/5 — Cleared the dreaded DEF loop

*2024-05-11*

When all other scanners and code readers failed, this app let me do a service bay test that cleared that code after I changed my NoX sensors. Cannot say enough good things!

## Frequently asked questions about Gretio

### What vehicles does Gretio support?

Gretio is made exclusively for General Motors vehicles. The app plans to support additional models in the future.

### What hardware is required to use Gretio?

You will need an OBDLINK MX+ device to perform diagnostic functions with Gretio.

### What kind of service functions can Gretio perform?

Gretio can perform advanced service functions such as diesel particulate filter service regenerations, selective catalytic reduction tests, power relay tests, and programming some features.

### How much does Gretio cost?

Gretio is free to download. There is a 'Gretio All Access' subscription available for $19.99 per year.

### What is the update frequency for Gretio?

Gretio was last updated on December 10, 2025, with version 1.07.09. This indicates regular updates are provided.

### What is the age rating for Gretio?

Gretio has an age rating of 4+, making it suitable for a wide range of users.

### What is the user rating for Gretio?

Gretio has a rating of 4.0 stars from 20 ratings, suggesting a generally positive user experience.

### Can Gretio be used on both iPhone and iPad?

Yes, Gretio is supported on both iPhone and iPad devices.

## Version history (last 5 releases)

### 1.08.02 — 2026-08-11

* Fixes Timeout errors with hardware periodic messaging enabled
* Global B now monitors power state to shut down automatically
* Dashboards can now locally record PID data to view later

### 1.08.01 — 2026-08-06

* Revamped vehicle control functions to support more complex scenarios and future capabilities
* Database is now smaller (faster to download) and more robust against poor network connectivity
* Grid mode now allows various sizes of adaptive tiles
* Grid mode now accepts stylized items such as graphs and gauges
* Module DTCs can be exported to clipboard

### 1.07.12 — 2026-05-08

Fixes crash which can occur when attempting to connect to an unsupported vehicle

### 1.07.11 — 2026-04-29

* Fix Disconnects preventing reconnecting to a device
* Fix Global B DDID/DPID Scheduling Issue
* New grid view format for Dashboard
* PID Screen now previews live data
* Fix regression in module time outs causing disconnects
* Misc other fixes

### 1.07.10 — 2026-04-29

* Fix Disconnects preventing reconnecting to a device
* Fix Global B DDID/DPID Scheduling Issue
* New grid view format for Dashboard
* PID Screen now previews live data like on the other version of Gretio on the other platform
* Misc other fixes

## Apps similar to Gretio

| App | Rating | Price | Category |
| --- | --- | --- | --- |
| [RSR Alignment App](https://appshunter.io/ios/app/rsr-alignment-app/id1503116170) | 3.0 (2) | Free | Productivity |
| [Rig Mechanic](https://appshunter.io/ios/app/rig-mechanic/id1605635549) | 3.9 (18) | Free | Productivity |
| [J1939OBD](https://appshunter.io/ios/app/j1939obd/id1453435912) | — | Free | Productivity |
| [ALFA OBD - Car Diagnostic App](https://appshunter.io/ios/app/alfa-obd-car-diagnostic-app/id6504546894) | 3.4 (106) | Free | Productivity |
| [Giotto ScanTool](https://appshunter.io/ios/app/giotto-scantool/id1294503417) | 3.3 (44) | Free | Productivity |
| [OBDAI OBD2 Scanner & ELM327 AI](https://appshunter.io/ios/app/obdai-obd2-scanner-and-elm327-ai/id6741182859) | 4.4 (12) | Free | Productivity |

---

*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-08-15.*