Why you should be concerned about OBD port connected GPS devices

If you are considering a telematics solution, the GPS hardware is the single most important factor. GPS Police Inc. has never used an OBD dongle GPS tracking device for four major reasons which will be covered in this article.

1. Warranty

In the eyes of the vehicle manufacturers, the port was initially meant to be an access to diagnostic data only. Today it is tricked into giving away access to more CPUs. As a defence, OEMs have employed various strategies to protect access to the CAN bus by hiding the port, making it inconvenient to use while driving or making the Diagnostic Trouble Codes (DTC) impossible to recognise by third party service providers.

The use of the OBD dongle has been widely reported — and in some cases it has translated into notes at the bottom of their warranty document threatening the users — that driving with an OBD dongle would cancel the manufacturers warranty.

Dongle manufacturers and insurers will legitimately claim the OEM cannot void the warranty if the dongle is used but they must be fully aware and made accountable for the risk they take if the causation of an accident is demonstrated to be the dongle’s interference with the car.

2. Safety

What happens when the device is connected to the vehicle while the vehicle is in operation? Some vehicles — or specific Electronic Control Units (ECU) — may shift automatically to diagnostic mode. This could have an impact on how data traffic is prioritised on the CAN bus which could cause the vehicle to malfunction because the priority might not be given to specific data as it would if the vehicle was set to normal driving mode.

However to the extent that the dongle may cause the vehicle to shift to diagnostic mode and to perform in a way that is unsafe for the use of the vehicle on public road, then there is an issue. Here the dongle will have to be made responsible for not unduly interfering with the data traffic on the car, or that it only extracts data when the vehicle is parked or stopped at a red light.

Unfortunately, the reality is the dongle will inject more requests into the CAN bus before, during and after an accident. This is precisely when interfering with the vehicle’s data network is subjected to the most risk. Specifically before the accident, OBD dongle manufacturers and service providers will want to be sure that the experts analysing the accident cannot identify its causes to the be data traffic initiated by the dongle.

This is a lose-all situation in which the driver safety concerned have been marginalised.

3. Reliability

In the world of telematics, GPS tracking devices are required to be connected to power and sustain cellular connection and maintain reliable GPS reception. Removing the device from it's OBD port renders it useless and the reporting of engine state, speed, location, etc. ceases. Because the OBD port is easily located in the foot well on the driver side of the vehicle, tampering is a concern since the device is so easily removable. Additionally since the OBD port is located so close to the floor, water, mud, debris, and general damage from workers boots can be caused.

Reliability for OBD based devices are reported to be the lowest in the industry and tampering is the highest.

4. Accuracy

Since GPS signals orginate from satellites in space 20,000km away, by the time they reach earth, and more specifically, the GPS telematics device, they are extremely weak. For this reason, GPS receivers can't be covered with metal, even metallic based films. GPS tracking devices connected low inside the vehicle at the OBD port, have a compromised view of the sky to the point where GPS validity and quality is unreliable at a professional level. OBD modules with an external antenna however improve the GPS reception dramatically.

Above is a photo of the GPS antenna built into the OBD dongle.

What about GPS Police?

What about the equipment we sell? We manufacture and sell a stand alone military grade GPS tracking device. Talk to an engineer at GPS Police today +1 (877) 411-1110.

Warranty and Safety

Our devices are 100% vehicle warranty safe and driver safe. They are installed into the vheicle and are not connected or interfaced to the vehicles electronics. No wires are cut. The device operates on a internal battery which is charged while the vehicle is running.


Our equipment is installed covertly under the dash where tampering, moisture, vibration, heat, cold, is minimized or eliminated. Many other constant use persistant electronics are safely installed and operating in these areas. To boast our reliability, our equipment is used in mission critical military, police, and EMS vehicles. We also sell our equipment with an unlimited lifetime warranty – even when customer installed.


Our equipment uses a military grade GPS receiver which out perform all other receivers in the consumer and commercial markets. More importantly, we provide a high level of detail regarding the GPS reception and performance for every event. When a vehicle reports a speed, you can see the HDOP, VDOP, PDOP values which give you "how reliably accurate" the location data is. We help the fleet managers make approriate actions based on accurate information.

What is the OBD port?

On-board diagnostics (OBD) is an automotive term referring to a vehicle's self-diagnostic and reporting capability. OBD systems give the vehicle owner or repair technician access to the status of the various vehicle subsystems. The amount of diagnostic information available via OBD has varied widely since its introduction in the early 1980s versions of on-board vehicle computers. Early versions of OBD would simply illuminate a malfunction indicator light or "idiot light" if a problem was detected but would not provide any information as to the nature of the problem. Modern OBD implementations use a standardized digital communications port to provide real-time data in addition to a standardized series of diagnostic trouble codes, or DTCs, which allow one to rapidly identify and remedy malfunctions within the vehicle.

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