Supplied and fitted at work shop in Newton Abbot, Devon.
 
This is a common request from insurance companies when insuring vehicles such as Motorhomes or Land Rover.
🚨 What Is a Cat 2>1 Upgrade Alarm?
If your vehicle already has a factory-fitted Thatcham Cat 2 immobiliser, such as many Land Rovers, vans, and motorhomes do, you don’t need to add a new immobiliser. Instead, a Cat 2>1 upgrade alarm adds the missing alarm components—interior sensors, siren, etc.—to elevate your system to full Cat 1 status.
This is especially useful for insurance purposes or for vehicles that are commonly targeted by thieves.
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⚙️ Example: Sigma S37 Cat 2>1 Upgrade Alarm
The Sigma S37 is one of the most popular and widely approved Cat 2>1 upgrade alarms in the UK. Here’s what it includes:
🔒 Perimeter Protection – triggers if doors, boot, or bonnet are opened while armed
🏠 Ultrasonic Interior Sensors – detects motion inside the vehicle
📢 118dB Battery Backup Siren – sounds even if the vehicle battery is disconnected
🧠 Automatic Arming & Re-arming – protects the vehicle even if you forget
🚗 Works With Factory Key – can often be programmed to arm/disarm using your original fob
🔑 Optional Touch Key Override – for extra security or if fob battery dies
Once installed with a valid Cat 2 immobiliser, the system qualifies the vehicle as Thatcham Category 1 compliant.
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✅ Summary
A Sigma S37 Cat 2>1 upgrade is ideal if your vehicle already has an immobiliser but lacks an alarm. It's cost-effective, insurance-approved, and adds a powerful layer of theft deterrence and protection—without the need for a full alarm and immobiliser refit.
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