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Gunson Gastester Digital G4125
The Gunson Gastester is a digital exhaust carbon monoxide (CO) analyser with a pulse pump, accurately measuring CO levels for testing and setting carburettors (leaded or unleaded petrol) and petrol injection systems on any vehicle. The digital display clearly shows the CO volume percentage, allowing the engine to be tuned for optimal performance and cleaner, more efficient running. Ideal for checking CO after carburettor, ignition, and air filter maintenance, as well as tuning pre-cat classic cars, motorbikes, and single-cylinder engines. The system is easy to use: a metal exhaust probe is held in place with a pair of retaining springs, and a flexible pipe connects the probe to the Gastester. The kit includes everything needed for accurate CO testing and is supplied with full instructions.
- A digital carbon monoxide tester for quick, easy checking of levels after engine maintenance work & tuning. Calibrates in air, no moving parts to wear out & no filters to change.
- Delivers accurate CO measurement to 0.5% at 15� to 25�C with adjustable calibration control for precise setting.
- 12V DC battery supply required. Supplied with 2 core cables with clips for easy attachment to the car battery.
- Contents: Gastester instrument including collector box & pulse pump/water trap assembly, metal exhaust probe with retaining springs, 3x flexible pipes & detailed instructions.
- The Gastester only measures the CO level in the exhaust gas & is therefore not suitable for MOT & diagnostic checks or vehicles fitted with catalytic converters where an accuracy greater than +/- 0.5% CO is required.
£144.67
BUY IT NOWNote to all customers in the EU, since Brexit the rules for VAT and customs charges have altered. If your item is over 150 euros then you are responsible for the VAT content and also customs charges for import.
These will be payable to your national delivery company or DHL. If your item is under 150 euros, eBay will charge you the VAT content on purchase but import duties will be payable on delivery. If items are refused it is eBay policy for you to lose your Money Back Guarantee, meaning you would not receive the product or get your money back.
Here at Top Rated Tools, we aim to deliver to you efficiently and cheaply, the majority of our products are available on an economy service for free but we do offer the option for expedited delivery.
We will dispatch items within 48 working hours of the order being processed. We process all order up until 2.30pm, after this time the order is processed the following day. For example, if you purchase at 5.00pm on Monday, your order is processed on Tuesday and we will have the item dispatched by Thursday at the latest.
We try to keep all our stock levels as accurate as possible but as we sell on multiple platforms sometimes there can be errors that lead us to not having stock of your item, if this happens we will offer a comparable replacement or a full refund.
These will be payable to your national delivery company or DHL. If your item is under 150 euros, eBay will charge you the VAT content on purchase but import duties will be payable on delivery. If items are refused it is eBay policy for you to lose your Money Back Guarantee, meaning you would not receive the product or get your money back.
Here at Top Rated Tools, we aim to deliver to you efficiently and cheaply, the majority of our products are available on an economy service for free but we do offer the option for expedited delivery.
We will dispatch items within 48 working hours of the order being processed. We process all order up until 2.30pm, after this time the order is processed the following day. For example, if you purchase at 5.00pm on Monday, your order is processed on Tuesday and we will have the item dispatched by Thursday at the latest.
We try to keep all our stock levels as accurate as possible but as we sell on multiple platforms sometimes there can be errors that lead us to not having stock of your item, if this happens we will offer a comparable replacement or a full refund.
INTERNATIONAL ORDERS ARE SUBJECT TO TARIFFS AND FEES IMPOSED BY YOUR OWN COUNTRY, WE CANNOT CALCULATE THIS FOR EACH COUNTRY THEREFORE IT IS NOT REFLECTED IN THE PRICE.
WE NOW OFFER A FULLY TRACKED SHIPPING OPTION AS STANDARD. TRACKING WILL BE UPLOADED AUTOMATICALLY, ALLOWING YOU TO FOLLOW THE SHIPMENT.
NORTHERN IRELAND SHIPPING
The majority of our smaller items all qualify for shipping at no extra cost, however, larger items to Northern Ireland are subject to a shipping fee of £10.00, this is because our suppliers will no longer ship direct to NI post Brexit. We will notify you in eBay messages if this is the case.
Remote Locations
Due to the vast amount of remote locations we cannot build in the facility for postage to know where you are based when ordering. For this reason if you are based in: Isle of Man, Guernsey, Jersey, Northern Ireland, Highlands & Islands or any other area that may be considered remote there may be a surcharge of £16.00 to cover the additional costs of courier delivering, this also applies to non-UK sales. We will always let you know if your location is classed as remote and seek another address to avoid the cost, you can also check your postcode with DHL at https://raslist.dhl.com/jsp/first.jsp.
Due to the vast amount of remote locations we cannot build in the facility for postage to know where you are based when ordering. For this reason if you are based in: Isle of Man, Guernsey, Jersey, Northern Ireland, Highlands & Islands or any other area that may be considered remote there may be a surcharge of £16.00 to cover the additional costs of courier delivering, this also applies to non-UK sales. We will always let you know if your location is classed as remote and seek another address to avoid the cost, you can also check your postcode with DHL at https://raslist.dhl.com/jsp/first.jsp.
**CHRISTMAS SHIPPING**
As Christmas approaches, we understand the importance of knowing whether your item will arrive to you before the big day. As such we have compiled a list of final delivery dates for all our customers in various countries. You must remember there is also the dispatch time to include when making your order, this is displayed in the listing. Here are the final dates for pre-Christmas delivery, please remember these are guidelines only and as always there can be delays in the shipping process, especially over the busy Christmas period.
Last Shipping Dates
UK - Friday 20th December
Australia, Brazil, Bulgaria, Cyprus, Finland, Greece, Israel, Italy, Malta, Mexico, Norway, Portugal, Romania and Sweden - Saturday December 7
Czech Republic, Malaysia, New Zealand, Poland, Saudi Arabia, Spain, Turkey and United Arab Emirates (UAE) - Monday December 9
Austria, Denmark, India, Lithuania, Philippines, Qatar, Slovakia and Slovenia - Wednesday December 11
Belgium, Canada*, China (People’s Republic), Croatia, Estonia, Hungary, Iceland, Latvia, Luxembourg, South Korea, Thailand and USA - Friday December 13
France, Germany, Hong Kong, Ireland, Japan, Netherlands, Pakistan, Russia, Singapore, Switzerland and Taiwan - Monday December 16
Royal Mail
We use Royal Mail for all packages under 2kg, the following guidelines apply for our standard packets:
UK- 3-5 working day delivery after dispatch
EU- 5-7 working day delivery after dispatch
Non-EU- 7-10 working day delivery after dispatch
We have the ability to track the items but not the facility to upload all the tracking details, therefore if you are worried about the location of your item please contact us prior to opening a case with eBay, we can usually deal with all issues before having to open cases with eBay or PayPal.
I think my item is lost
It's very rare for parcels to be genuinely lost by Royal Mail however they can on occasions be delayed by:
Mis-routing in the delivery network or...
Incomplete delivery addresses or...
The most common reason for non delivery of parcels sent via Royal Mail is that they are too large for a standard letterbox and have been taken back to the local Royal Mail Delivery Office or Enquiry Office.
Postmen and women may also leave parcels with neighbours, behind bins or in outhouses etc.
Still no luck...
If you have waited 10 working days from receipt of our despatch email please contact us using the 'Ask a Question' link on the item listing. We will need the following points confirming:
You have visited your local Royal Mail Delivery Office or Enquiry Office (Not the Post Office)
Your full delivery address including postcode
That you have checked with neighbours and other occupants at the delivery address
Your contact phone number
You agree to return to us, at our cost, any replacement items which subsequently turn up
You agree that we can pass your details to Royal Mail and that you will respond to enquiries from them.
What we will do
Where you have confirmed in writing that your item has not been received and all of the above information has been provided we will arrange a replacement item. Royal Mail will not allow claims until 15 working days have passed from dispatch and we reserve the right to wait until this time has passed before we replace lost items.
Sadly instances of fraud are on the increase. The cost of fraud has to be passed on to all buyers in the form of higher costs. Because of this all reports of lost items are reported to Royal Mail who may contact you to confirm the circumstances of the loss. For your security and to minimise theft, where the item is valuable or you have a history of non-receipt we may also ask you to report the loss via eBay before we can action any replacement.
Tool Time International is a tool supplier based in North Yorkshire, and has been an online presence since 2003. We have multiple online stores and offer a comprehensive selection of items covering all needs including: Home & DIY, Industrial, Mechanics Tools, Gardening, Building Supplies and much more. If you can't see it on the site please let us know as we can usually source it for you!
With over 30 years experience in the trade and mechanical knowledge we offer a dedicated and knowledgeable customer support system that is always on hand to advise and help with any problem you may have.
We ship around the globe and don't impose restrictions on where we ship to unless our courier is unable to reach you! We use the most reliable shipping services including Royal Mail, DHL and have a fully implemented tracking service for most products.
When you purchase from Tool Time International, you can rest assured that the product will be of the highest quality as well as the aftercare we offer, this includes dealing with any problems you may have from shipping delays to warranty returns. As a small business you know you will be able to deal with the same member of the customer service team with your problem rather than waiting on hold or having to deal with an automated call centre.
Our experience has allowed us to develop strong professional links with the top suppliers of tools in the UK, we offer the very best products from the major players in a range of industries. We cover all bases from cheaper DIY Tools to top-end industrial parts.
Take a look and rest assured we will do our best to provide a one-stop shop for all your needs!
There are many ways to contact Top Rated Tools but the quickest and easiest way to get in touch with us is via the eBay messaging system. We answer our eBay messages at regular intervals and will get back to you with an answer within 24 hours.
You can also contact us via the phone if you have a customer service problem or if you would like to complete payment through credit or debit card, our details can be found on the 'Business Details' page provided by eBay.
Here at Top Rated Tools, we encourage customers to contact us directly if you have a problem with an item or delivery of an item. We are usually able to deal with any problem and remedy it without using the eBay appeals case, we encourage customer's to use this only as a last resort and we will do everything we can to help you and make sure you get the best customer service possible.
If you are looking to return an item or you would like to send us a cheque or postal address please send to the address on our Business Details provided by eBay.
You can also contact us via the phone if you have a customer service problem or if you would like to complete payment through credit or debit card, our details can be found on the 'Business Details' page provided by eBay.
Here at Top Rated Tools, we encourage customers to contact us directly if you have a problem with an item or delivery of an item. We are usually able to deal with any problem and remedy it without using the eBay appeals case, we encourage customer's to use this only as a last resort and we will do everything we can to help you and make sure you get the best customer service possible.
If you are looking to return an item or you would like to send us a cheque or postal address please send to the address on our Business Details provided by eBay.
WE DO NOT COMPLETE SALES OUTSIDE OF EBAY SO PLEASE DO NOT CONTACT US TO TRY AND DO SO.
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WHAT OUR CUSTOMERS ARE SAYINH ABOUT US
| Feedback/item | From Buyer | Date/time | |
Delivery was poor and let the seller down
seller was good Gunson Gastester Digital G4125 | stebucki_58 (181) | 12/01/2026 | |
 | Order delivered on time with no issues Gunson Gastester Digital G4125 | madsps (125) | 09/01/2026 |
| Order delivered on time with no issues Gunson Gastester Digital G4125 | gueissaz1917 (581) | 31/12/2025 |
| Order delivered on time with no issues Gunson Gastester Digital G4125 | vi_33867 (0) | 18/12/2025 |
| Order delivered on time with no issues Gunson Gastester Digital G4125 | tiers93 (949) | 18/12/2025 |
| Order delivered on time with no issues Gunson Gastester Digital G4125 | daz0071975 (813) | 18/12/2025 |
| Order completed successfully—tracked and on time Gunson Gastester Digital G4125 | la669966 (442) | 17/12/2025 |
 | Product defective. Powers on when connected but then display goes dimmer and dimmer until shutting off. Tested it in two cars. IImage and video provided. Seller tell me to contact manufacturer. Contacted by email, waiting for manufacturer response. Since I'm in Portugal, calling UK numbers are extremely expensive. Gunson Gastester Digital G4125 | sandstorm_rs (67) | 14/12/2025 |
Cheap junk. Did not think it would be so cheap and nasty. Did not work. Perhaps just my set up so decided against neg feedback Gunson Gastester Digital G4125 | chyrelw123 (1261) | 11/12/2025 | |
| Order delivered on time with no issues Gunson Gastester Digital G4125 | emanmar43 (159) | 10/12/2025 |
