--- product_id: 13752551 title: "Gunson G4125 Gastester Digital" brand: "gunson" price: "€ 435.22" currency: EUR in_stock: true reviews_count: 13 category: "Gunson" url: https://www.desertcart.es/products/13752551-gunson-g4125-gastester-digital store_origin: ES region: Spain --- # 0.5% CO accuracy Calibrates in air, no filters No moving parts, zero wear Gunson G4125 Gastester Digital **Brand:** gunson **Price:** € 435.22 **Availability:** ✅ In Stock ## Summary > ⚡ Tune like a pro, breathe easy with precision! ## Quick Answers - **What is this?** Gunson G4125 Gastester Digital by gunson - **How much does it cost?** € 435.22 with free shipping - **Is it available?** Yes, in stock and ready to ship - **Where can I buy it?** [www.desertcart.es](https://www.desertcart.es/products/13752551-gunson-g4125-gastester-digital) ## Best For - gunson enthusiasts ## Why This Product - Trusted gunson brand quality - Free international shipping included - Worldwide delivery with tracking - 15-day hassle-free returns ## Key Features - • **Instant Air Calibration:** Calibrates directly in ambient air—ready to use, no extra setup required. - • **Maintenance-Free Design:** No moving parts or filters means hassle-free, long-lasting reliability. - • **User-Friendly Operation:** Clear, easy-to-follow instructions make tuning your classic or modern vehicle a breeze. - • **Precision CO Measurement:** Pinpoint your petrol/air mix with 0.5% accuracy for peak engine performance. - • **Trusted British Engineering:** Crafted in the UK with decades of automotive expertise and ethical sourcing. ## Overview The Gunson G4125 Gastester Digital is a UK-made, highly accurate gas analyzer designed for tuning carburettors and petrol injection systems. Featuring 0.5% CO measurement accuracy, no moving parts, and air calibration without filters, it offers a durable, maintenance-free solution trusted by classic vehicle technicians and modern mechanics alike. ## Description Gastester is used for the testing and setting of all carburettors (petrol, leaded or unleaded) and petrol injection systems on any vehicle.Gastester provides a simple and inexpensive method of showing when the correct petrol/air mixture is being dispensed A British tool company based in Warwickshire, United Kingdom. Gunson Tools draws on years of experience to introduce quality products which offer real value for money. All our products are responsibly sourced both from trusted ethical partners across the world PLUS (uniquely as an automotive tool brand) our own manufacturing base in the UK. Trusted quality products like Eezi-Bleed, ColourTune, Carbalancer and Eezi-lap are just a few names within the range. Combining our British manufacturing, our years of experience and vast expertise in the automotive sector helps us achieve our aim of bringing high quality tool solutions first to market and being No.1 choice for the Classic vehicle technician Review: Worked exactly as advertised.. - I suspected I had a rich mixture so I bought this. I followed the instructions and I adjusted my mixture until I reached the target CO spec (for an older Porsche 928) and now the car runs better than it ever has before. I recommend. Review: Works well - read the directions! - Works well for tuning vintage autos, but read and understand the directions! Proper calibration is key - this isn't a toy, you have to think about how you are using it. ## Features - Content includes: Gas tester instrument including - Calibrates in air, no moving parts to wear out - No filters to change - Accurate to 0.5% C.O measurement at 15-25˚C - Easy to follow instructions ## Technical Specifications | Specification | Value | |---------------|-------| | ASIN | B002XF1VW6 | | Best Sellers Rank | #884,837 in Automotive ( See Top 100 in Automotive ) #12 in Gas Analyzers | | Brand | GUNSON | | Customer Reviews | 4.0 4.0 out of 5 stars (300) | | Date First Available | August 16, 2012 | | Is Discontinued By Manufacturer | No | | Item Weight | 1.1 pounds | | Item model number | G4125 | | Manufacturer | Tool Connection (EU) | | Manufacturer Part Number | LASG4125 | | Model | G4125 | | Product Dimensions | 5.24 x 9.65 x 7.2 inches | ## Images ![Gunson G4125 Gastester Digital - Image 1](https://m.media-amazon.com/images/I/71Bthmee96L.jpg) ## Questions & Answers **Q: What gases does it test? 02, HC, ???** A: This reads O2 only. Thanks Ben **Q: How many/ which gases does this tool measure?** A: Has anyone actually used this, and does it perform well enough to go by its measurements before smog so I can tune and then smog same day if possible???? **Q: Can it meassure HCppm, CO%, CO2%, NOXppm? This is requirement in Mexico.** A: No, it is strictly for CO%.Cheers! **Q: Can this be used to test the radiator for head gasket leaks?** A: No, measures only combustion by-product CO or Carbon Mon-oxide. Used to adust or test fuel mixture. ## Customer Reviews ### ⭐⭐⭐⭐⭐ Worked exactly as advertised.. *by T***D on July 13, 2022* I suspected I had a rich mixture so I bought this. I followed the instructions and I adjusted my mixture until I reached the target CO spec (for an older Porsche 928) and now the car runs better than it ever has before. I recommend. ### ⭐⭐⭐⭐⭐ Works well - read the directions! *by C***K on April 7, 2022* Works well for tuning vintage autos, but read and understand the directions! Proper calibration is key - this isn't a toy, you have to think about how you are using it. ### ⭐⭐⭐⭐ Decent analyzer; seems a tad expensive *by F***C on April 6, 2016* The unit is a bit cheaply made (plastic), and not robust at all. However, it seems to work OK. Has sufficient length power cable and the plastic exhaust tubing is long enough. So far the plastic tubing hasn't melted. The CO readings seemed to fall in line with what the NJ state inspection station reading for CO was. I have only used it twice, and will revisit to adjust my rating at some point down the line. ## Frequently Bought Together - GUNSON G4125 Gastester Digital - GUNSON G4074 Colortune Single Plug Kit 14mm --- ## Why Shop on Desertcart? - 🛒 **Trusted by 1.3+ Million Shoppers** — Serving international shoppers since 2016 - 🌍 **Shop Globally** — Access 737+ million products across 21 categories - 💰 **No Hidden Fees** — All customs, duties, and taxes included in the price - 🔄 **15-Day Free Returns** — Hassle-free returns (30 days for PRO members) - 🔒 **Secure Payments** — Trusted payment options with buyer protection - ⭐ **TrustPilot Rated 4.5/5** — Based on 8,000+ happy customer reviews **Shop now:** [https://www.desertcart.es/products/13752551-gunson-g4125-gastester-digital](https://www.desertcart.es/products/13752551-gunson-g4125-gastester-digital) --- *Product available on Desertcart Spain* *Store origin: ES* *Last updated: 2026-04-22*