Build Quality, Side by Side
Why our mileage blockers cost a little more
A blocker sits behind your instrument cluster, plugged into the car’s own wiring. We put ours next to a cheaper alternative and photographed both, so you can see exactly where the difference in price goes.
- Factory plugs
- Pins enclosed
- Heat-resistant cable
- Generic headers
- Pins on show
- Thin loose wire
At a Glance
Feature by feature
| What to look for | Autotech UK | Carcode |
|---|---|---|
| Connector type | Manufacturer factory plugs | Generic pin headers |
| Locking lever | Clicks home and stays put | None on the unit we examined |
| Fits one way only | Keyed factory shroud | No factory shroud to guide it |
| Pins protected | Fully enclosed | Bare pins exposed |
| Cable | Heat-resistant, colour-coded | Thin, all one colour |
| Loom finish | Fabric-taped, rattle-free | Loose wires |
Why It Matters
The cheapest blocker can become the most expensive one
You’re usually fitting it by feel, behind a half-removed dash. Here’s what a plug that doesn’t guide you in can lead to.
Plug goes on misaligned
No shroud or locking lever means nothing stops it going on offset or flipped.
Wrong pins connect
Power can reach a data line, or exposed pins can bridge each other or touch bodywork.
Expensive damage
An instrument cluster or control module can cost far more to replace than you saved on the blocker.
Look Closer
Three things you can see with your own eyes
01The plugs
Manufacturer factory connectors
The same style of housing your car’s harness uses, with a locking lever that clicks home. Keyed, so it only fits one way.
Generic pin headers
Plain white housings with no locking lever. Without a factory shroud guiding it, the plug is easier to offer up at the wrong angle or the wrong way round.
02The pins
Contacts fully enclosed
Every terminal sits inside a shrouded housing, protected from bending, shorting and dirt while you fit it behind the dash.
Pins left on show
Bare male pins stick out of the housing. They can bend, touch each other or touch metal behind the dash while you’re fitting it.
03The wiring
Heat-resistant, colour-coded, fabric-taped
Heat-resistant automotive cable, colour-coded like the factory loom, wrapped in fabric tape so it sits quietly behind the dash without rattling.
Thin, loose, all-black wire
Thin single-colour wires with no sleeving between the plugs, so there’s no way to tell one circuit from another if you ever need to check it.
Where the Extra Goes
What you’re paying for
Factory plugs
Manufacturer connectors cost more than generic headers. They’re why it fits first time.
Heat-resistant cable
Behind a dash gets hot. Our cable is made for it, and colour-coded so it can be traced.
Top-grade components
The highest-quality chips and electrical parts we can source, for reliable CAN bus operation.
Tested and backed
Every unit is tested before dispatch, with UK support, fitting guides and video-call help on WhatsApp.
Buying From Anyone?
5 checks before you buy a mileage blocker
Ask the seller for close-up photos of the actual plugs. If they won’t show you, that tells you something.
- Are the plugs the same as the car’s? Factory-style connectors, not generic white headers.
- Does it lock? Look for a locking lever or latch that clicks home.
- Are the pins covered? Bare pins can bend, short or touch metal.
- What’s the cable like? Heat-resistant, colour-coded and properly wrapped.
- Who’s behind it? A real warranty, returns and someone to call when you’re fitting it.
Pay a little more once. Fit it right first time.
UK-made mileage blockers from £279, with a 12-month warranty and 28-day money-back guarantee.
Comparison photos taken by Autotech UK in October 2026 of one Carcode unit purchased from mileageblockers.com. Other Carcode products, or later versions, may differ. Carcode is a trademark of its owner and is named for comparison only.
For lawful use only. Mileage blockers are intended for dyno testing, diagnostics, track days and off-road use, and must not be used to misrepresent a vehicle’s true mileage or history.