ZDNET Says $2 OBD2 Fuel-Saver Dongles Can Damage Cars, Not Cut Fuel Use

Q: Beyond being a scam, how can a cheap plug-in gadget actually pose a fire risk to your vehicle?

Yes. The fire risk comes from bad electrical design and poor assembly, not from any real “tuning.” ZDNET’s teardown found these OBD2 “fuel saver” dongles are mostly empty shells with a simple timer chip, LEDs and a few basic components, often built to very low standards. In a vehicle, that matters because the OBD2 port supplies power. If the gadget has loose wires, weak insulation, cracked or sloppy solder joints, or excess solder bridging contacts, it can create a short circuit or a high-resistance connection that overheats. That overheating can melt the dongle’s plastic, damage the port, or ignite nearby material. Vehicle vibration and temperature swings make the risk worse: poor solder joints can loosen further, wires can shift, and intermittent contact can cause arcing. Arcing produces intense localized heat and is a known ignition hazard in electrical systems. There is also a mechanical risk that can become an electrical one. Investigators found some units with poorly secured pins; if a pin breaks off and stays lodged in the OBD2 socket, it can damage the port or create an unintended electrical path, leading to more shorts, blown fuses, or heat buildup. So the danger is not that the gadget secretly changes engine settings. It is that a cheaply made device plugged into a live vehicle circuit can fail electrically, overheat, and in the worst case start a fire.

1 articles · Updated · ZDNet · Jun 23

ZDNET found common “fuel saver” OBD2 dongles sold for a few dollars to over $30 for two contain little more than LEDs, a timer chip, resistors and a button.
The devices do not remap a car’s computer as advertised; the outlet said they simply blink when powered, making them fake tuning tools rather than fuel-saving hardware.
Poor assembly creates the real risk: loose solder or wires can trigger short circuits or even fires, and pins can break off in the OBD2 port, leading to costly repairs.
Instead of plug-in gadgets, ZDNET urged drivers to use basic maintenance and driving habits, noting tires 10 psi low can cut fuel economy by as much as 3%.