Police say that jammers are found in many stolen cars and are easy to build.
They work by blocking the satellite signal to the GPS receiver or preventing GSM-based communication with the tracking device.
Mr Walls said: "Whilst GPS/GSM devices have their place in stolen vehicle recovery, there really shouldnt be sole reliance on this technology."
He added that there is an "over-reliance" on GPS, as many motorists do not realise its vulnerabilities, believing it is tamper-proof.
Meanwhile, drivers have been warned that car insurance claims rise by five per cent as the clocks change.
Insurer More Than has advised drivers to take simple precautions such as using lights and avoiding all alcohol before driving to reduce the risks of having an accident.
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