For most cars that are driven regularly, yes: a well-built device is designed to stay in the OBD port permanently. There are three real caveats. A car parked for weeks can run its battery down. Your carmaker's warranty terms may be stricter than you expect. And a tracker knows where you go, so who holds that data matters more than anything the port itself exposes.
We sell one of these devices, so read this with that in mind. We have tried to lay out what is true, including the parts that don't help us. If you are new to OBD, our OBD2 explainer covers the basics.
Will an OBD device drain my car battery?
The OBD port has a pin that is connected to the battery all the time, whether the ignition is on or off. That is what lets a device notice the moment the engine starts. It also means anything plugged in can draw power while the car is parked.
Two numbers get mixed up here, so it is worth separating them:
- Reporting interval is how often the device sends an update while you drive. Ours sends a location update about every 30 seconds while the car is running.
- Sleep current is how much power the device draws from the battery while the car is off and the device is in its low-power mode. It is measured in milliamps (mA), and it is the number that decides battery drain.
A well-designed tracker detects that the ignition is off and drops into a low-power sleep mode. Our Teltonika OBD device supports this. A cheap device without a proper sleep mode keeps drawing close to its running current all night.
What that means in practice
Some rough arithmetic helps. Maruti Suzuki's manuals list batteries of 33 to 45 Ah for the Wagon R and Brezza. A device drawing 10 mA while parked uses 0.24 Ah a day, or about 3.4 Ah over two weeks. That is under a tenth of a 38 Ah battery, before counting the car's own standby drain from the clock, alarm and key receiver.
So on a car you drive most days, a sleeping device is a rounding error. On a car left for a month, the device's share adds to everything else, and an older battery that was already marginal may not start the car. Carmakers treat long parking as the owner's responsibility too: Maruti's warranty policy excludes battery damage caused by prolonged parking.
What to do:
- If the car will sit unused for more than two or three weeks, unplug the device, or accept that you should check the battery before you need the car. Unplugging stops tracking, so it is a trade-off.
- If the car already cranks slowly, fix the battery first. A device will make a weak battery's problems show up sooner.
- Watch the battery voltage if your device reports it. A reading that keeps drifting down from week to week is an early warning, whatever the cause.
Does an OBD device void your car's warranty in India?
This is the question where we see the most confident answers online in both directions, so a disclaimer first: we are not lawyers, and this isn't legal advice. Here is what the documents we could actually read say.
What carmakers' own documents say
Maruti Suzuki is unusually direct. Its owner's manuals (we checked the Brezza, Ertiga and Wagon R) carry a notice that the diagnostic connector is meant only for Maruti's specified diagnostic tool, and that connecting any other device may interfere with the electronics and run the battery down. Its warranty policy lists exclusions that include vehicles modified with performance accessories, and vehicles where parts or accessories not approved by Maruti Suzuki have been used.
Read literally, that second exclusion is broad. It doesn't say the accessory has to have caused the fault. We don't know how strictly dealers apply it in practice, and it will depend on the claim, but it would be dishonest to tell you it doesn't exist. Other carmakers word their warranties differently, so the only answer that holds for your car is the one in your own warranty booklet.
What the competition regulator has said
In August 2014, the Competition Commission of India ruled against 14 carmakers over how they restricted spare parts, diagnostic tools and independent repair. One of its directions was that carmakers must not impose a blanket condition cancelling the warranty just because the owner used an independent repairer. They could cancel it only to the extent that damage was caused by faulty repair work outside their network. The order was later challenged on appeal.
That ruling is about repairs, not plug-in devices, so it doesn't settle the question. It does show the direction Indian regulators took: warranty refusals are expected to connect to actual damage, not be a blanket penalty.
What we would actually do
- Read the exclusions section of your warranty booklet before plugging anything in.
- If you are still under warranty and unsure, ask your dealer in writing whether a plug-in OBD tracker affects your cover, and keep the reply.
- Unplug the device before a service visit. The workshop needs the port for its own tools anyway.
- If you are taking the car in for an electrical fault, tell them a device was plugged in. It helps them rule it out, and it is the honest thing to do.
What can an OBD device access? Data and security
The OBD port isn't only a data outlet. It connects to the car's internal network, the same network workshop tools use to program modules and new keys. That is why police in Houston have warned about thieves using the OBD port to program keys for vehicles they steal, and why some owners fit a lock over the port. (If you do fit a port lock, you can't also keep a device in the port.)
A device that only reads standard data doesn't use that power. But the more sensitive data from a tracker isn't engine data at all. It is where you go, when, and how you drive. That is what you are really trusting a vendor with.
Questions worth asking any vendor, including us:
- Does the device only read data from the car, or can it send commands to it?
- Where is my data stored, and who inside your company can see it?
- Do you sell or share data with anyone, such as insurers, lenders or advertisers?
- Can I delete my trip history and my account, and what happens to the data if I stop paying?
- How are firmware updates delivered, and how do you stop someone else pushing one?
- If I share access with family or a driver, what exactly can they see?
Our answers are in our privacy policy. If a question isn't answered there, email us at vialoop@404minds.com and we will answer it, and fix the policy.
Cheap OBD dongles vs branded hardware
Two different kinds of product get called “OBD devices”, and it helps to keep them apart.
Scan dongles are small Bluetooth or Wi-Fi readers that pair with a phone app. They are inexpensive, and plenty of them work fine for reading a fault code or watching live data on a drive. They are designed to be plugged in when you need them.
Trackers have their own GPS, SIM and motion sensors and are designed to stay plugged in for years. Here the hardware matters more, because it spends every night drawing power from your battery and every day sending your location somewhere.
Unbranded hardware isn't automatically bad, but with an unknown maker you usually can't find out the things above: the sleep current, whether firmware is ever updated, and where the data goes. Our device is made by Teltonika, a European manufacturer of vehicle tracking hardware that publishes documentation for its devices and supports them with firmware updates. That isn't the only way to get a trustworthy device, but it means the questions have answers. Our car tracker checklist covers how to judge any option.
When not to use an OBD device
There are situations where we would tell you to skip it, or wait:
- The car sits for weeks at a time and you won't unplug it or check the battery.
- The battery is already weak. Replace it first.
- Your warranty excludes non-approved accessories and you are not comfortable with that risk. Wait until the warranty ends, or get the dealer's answer in writing.
- The car has an unresolved electrical or network fault, especially codes starting with U. Fix it before adding anything to the port.
- The device would sit where your knee or the pedals can hit it. Use a flat extension cable, or don't fit it. Part 1 covers where the port is on popular Indian cars.
- You want it as your only theft protection. An OBD device in a known location can be unplugged. We explain why in what happens when a car is stolen in India.
For everyone else, the useful question isn't whether OBD devices are safe in general. It is whether this particular device sleeps properly, and whether its maker will tell you where your data goes. If you want to know what you get in return, part 3 covers what the port can and can't tell you, and part 2 explains whether your car has OBD2 at all.
Frequently asked questions
Is it safe to leave an OBD device plugged in all the time?
For a car that is driven regularly and has a healthy battery, a well-built OBD device is designed to stay plugged in. The cases to be careful with are cars parked for weeks at a time, cars with a weak battery, and cars whose warranty terms exclude accessories the carmaker hasn't approved.
Will an OBD device drain my car battery?
Every device draws some current while the car is off, because the OBD port stays powered. A device with a proper sleep mode draws little enough that a regularly driven car won't notice. On a car left unused for several weeks, that small draw adds to the car's own standby drain and can matter, especially on an older battery.
Does an OBD device void the car warranty in India?
It depends on your carmaker's warranty terms, and we are not lawyers. Some are broad: Maruti Suzuki's warranty policy, for example, excludes vehicles fitted with parts or accessories it hasn't approved, and its manual warns against connecting devices other than its diagnostic tool to the port. Read the exclusions in your own warranty booklet, and ask your dealer in writing if you are unsure.
Can an OBD device damage my car?
A well-made device that only reads standard data is very unlikely to. The port connects to the car's internal network, though, so a badly made device can in principle interfere with it. Stick to hardware from a known manufacturer and remove any device if the car starts showing electrical faults.
What is sleep current?
Sleep current is the electrical current a device draws from the car battery while the car is switched off and the device is in its low-power mode. It is measured in milliamps and is different from how often the device reports its location while you are driving.