Understanding OBD2 Protocols (CAN, SAE J1850, ISO 9141, K-Line), And GPS Tracker Compatibility

Ever plug in an OBD GPS tracker and the darn thing just sits there? No lights, no data, and nothing? 

Yeah, I’ve seen that headache more times than I can count in my 15+ years of testing trackers. Half the time, the tracker isn’t broken at all, it’s just your car speaking a different language.

Think of it like this, your car talks in a certain “language.” Some use CAN, some use J1850, others mumble in ISO 9141 or K-Line. If your tracker doesn’t speak the same language, they’re not having a conversation and they’re just staring at each other in silence. Frustrating, right?

By the time you finish reading this, you’ll know exactly which protocol your car uses, why it matters, and whether that GPS tracker you’re eyeing will work without a hitch. That means no wasted money, no compatibility guesswork, and a whole lot less stress the next time you plug into that OBD2 port.

What Is OBD2? Why Protocols Matter for GPS Tracker Compatibility

Alright, let’s strip the jargon. OBD2 stands for On-Board Diagnostics, and since 1996 every car sold in the U.S. has come with one of these ports tucked under the dash.

Why? Uncle Sam said so.

The idea was simple, give mechanics (and now GPS trackers) a way to plug in and see what the car’s brain is thinking. Here’s the kicker though, the port itself is the same shape in every car, but the language spoken inside that port isn’t universal. 

Now here’s the thing, while the port shape never changes, the ‘language’ under the hood can be all over the place. Think of the port like a phone jack. You can plug in, sure, but unless you speak the same “dial tone,” the call’s going nowhere.

And here’s a serious one for you: since 2008, CARB (California Air Resources Board) required all U.S. vehicles to speak CAN Bus (ISO 15765-4). Which means if your car was built in 2008 or later, you’re in the clear, your tracker will almost certainly understand it.

But before that, they might be whispering in SAE J1850, ISO 9141, or K-Line. And not every OBD GPS tracker speaks those old dialects. People get tripped up because the plug looks the same, but the language inside can be completely different.

So, OBD2 is the port, protocols are the language. And if your tracker can’t “talk the talk,” you’re not getting any data.

The 5 OBD2 Protocols Explained 

Alright, here’s where the rubber meets the road. Every OBD2 port speaks one of a handful of “languages.” Some are sharp and modern, others are… well, a little cranky and outdated.

Let’s break them down so you’ll know exactly what you’re dealing with.

CAN Bus (ISO 15765-4)

If your car was built in 2008 or later in the U.S., it runs on CAN Bus. This is the gold standard protocol; fast, reliable, and basically the plain English of car communication.

Most OBD2 GPS trackers work perfectly with CAN. Plug it in and you’re set. The only hiccup? Some manufacturers hide extra data like fuel or temp readings, so a tracker might show you location but not every stat.

Still, with CAN you’re in the safe zone, so no real guesswork, just easy compatibility.

SAE J1850 (PWM & VPW)

Now we’re talking about the old guard. Pre-2008 Fords leaned on J1850 PWM, while GM loved J1850 VPW. Solid in their time, but they’ve aged like flip phones.

• Still works fine if your tracker supports it.
• The catch? Many modern trackers don’t bother with SAE J1850 anymore, it’s just not worth their time.

So if you’re driving an older Ford truck or a classic GM, you’ll want to double-check before you buy a tracker. Otherwise, you might plug it in and get a whole lot of nothing.

ISO 9141-2

This one had its moment, especially in Asian and European cars before 2008. Toyota, Honda, and even some Chryslers liked to roll with ISO 9141.

• Simple protocol, easy to work with.
• Widely used in its heyday.
• But slow compared to CAN, and most new trackers don’t support it anymore.

Think of ISO 9141 like dial-up internet. It got the job done back in the day, but if you’re trying to stream Netflix on it now? Forget about it.

ISO 14230 (KWP2000 / K-Line)

This one’s basically the big brother of ISO 9141. You’ll see it in older Japanese and European cars; VW, Audi, BMW, and plenty of imports. K-Line is a little more advanced, a little more flexible than its predecessor. But here’s the reality:

• Broader support than ISO 9141.
• Still a legacy protocol, and tracker compatibility varies wildly.

If you’re driving an older German sedan or a quirky import, don’t assume your OBD2 GPS tracker will just work. Always check the spec sheet. Otherwise, you’ll be staring at a tracker that powers on but never talks back.

 Which Cars Use Which Protocol?

Now let’s make this super clear. You don’t need a PhD in car electronics to figure it out, just look at the year or the brand. Here’s the breakdown:

By Year (U.S. Standard)

For anything 2008 or newer, you’re safe, it’s all CAN, no second-guessing. But if you’re rolling in an early 2000s Toyota or a Ford truck from your college days, check first before assuming your tracker will ‘just work.

By Brand (Examples, Pre-2008)

So, if you’ve got a 2008+ car in the U.S., you’re golden, the CAN all the way. But if you’re rolling in an older Ford truck, a 2003 Chevy, or a 2001 Toyota, you’ll want to check which protocol it’s whispering in before assuming your tracker will “just work.” Saves you from plugging in and getting dead silence.

How to Check Your OBD2 Protocol

Alright, so you don’t want to guess. You want to know what protocol your car uses before you throw money at a GPS tracker. Good call. Here are the three easiest ways to check.

1. Check by Year

Here’s the quick rule: 2008 and newer means protocol is CAN and no ifs, ands, or buts.

If you’re behind the wheel of something older, you’ll need to dig a little deeper because pre-2008 cars might be speaking J1850, ISO 9141, or K-Line. It’s kind of like dating a newer models are predictable, but with the older ones, you really need to ask the right questions first.

2. Check the Pins (1-Minute Pinout Test)

Don’t worry, this isn’t scary. Just slide under your dashboard, look at the OBD2 port, and check which pins are wired. That tells you the language right away:

• Pins 6 and 14 connected means you’re on CAN, an easy win.
• Pins 2 and 10 in place usually signal J1850, which was common in older Ford and GM rides.
• Pin 7 (and sometimes 15) points to ISO 9141 or K-Line.

Pretty simple, it’s like looking at a smile and noticing which teeth are missing. The pattern tells the whole story.

3. Use a Scanner or App

This is the lazy-but-smart move. Grab an OBD2 scanner or even a cheap Bluetooth dongle with an app, and you’ll know the protocol in seconds. No guessing games and no crawling under the dash with a flashlight.

Honestly, I tell people to go this route if they don’t feel like getting dust on their shirt, I sure don’t. Picture it like a quick flowchart in your head:

Check the year → glance at the pinout → confirm with a scanner or app. Simple.

Doing it this way saves you time, saves you cash, and gives you certainty. You’ll know right away if your GPS tracker is about to plug in and play… or plug in and pout.

OBD2 GPS Tracker Compatibility

So, here now is the main part that really matters. You don’t care about acronyms just for fun, you want to know if your GPS tracker will actually work when you plug it in.

 Let’s break it down.

2008+ Vehicles (Most Readers)

As we discussed multiple times, if your car or truck was built in 2008 or later in the U.S., you’re in luck. Almost every OBD2 GPS tracker on the market works with CAN. That means plug it in, open the app, and bam, you’re tracking in real time.

The only small catch? Some automakers like to lock down advanced data. 

So yeah, you’ll get speed, location, and mileage, but you might not always see things like fuel levels or coolant temp unless the tracker specifically supports it. Still, for the core OBD GPS tracking stuff, 2008+ easy and smooth sailing.

Pre-2008 Vehicles

Now, this is where the waters get choppy. Older vehicles could be running J1850, ISO 9141, or K-Line, and not every tracker plays nice with those.

If you’re driving, say, a 2003 Ford F-150 or an early 2000s Toyota, you’ll need to be extra careful. Some universal trackers will handle those protocols, but plenty won’t. So, why I always tell people, double-check the specs before you buy. Otherwise, you might end up with a tracker that lights up but doesn’t talk back.

In some cases, you’ll need a specialized GPS tracker built for legacy OBD2 protocols. Sure, it’s a little annoying, but it beats wasting money on the wrong device.

EVs, Hybrids & Heavy-Duty Vehicles

Now let’s get real for a second. Electric cars, hybrids, and especially heavy-duty trucks sometimes don’t even play by the same OBD2 rules. Many big rigs, for example, run on J1939, which is a totally different protocol.

So if you’re in a Tesla, a Prius, or a semi truck, don’t just assume any old OBD2 GPS tracker is going to work. Check with the tracker provider first, or you might be in for a rude surprise.

Quick Buyer Checklist

Here’s the easy cheat sheet to keep you out of trouble:

• Year of your car: 2008+ is almost always CAN; older means check.
• Protocol check: Look at the pins or use an app.
• Tracker spec sheet: Make sure it lists your protocol before you buy.

Follow those three steps and you’ll avoid the #1 mistake I’ve seen folks make with OBD2 GPS trackers: buying blind.

Common Problems & Fixes

Alright, so let’s say you plug in your shiny GPS tracker and things don’t go as planned. 

Don’t panic. Most problems aren’t deal-breakers, and I’ve seen them all in the past 15 years. Here’s how to spot what’s really going on.

1. Tracker won’t connect?

Nine times out of ten, the reason is a protocol mismatch. If your car is older than 2008, check the year and the pins. Odds are your ride is speaking J1850 or ISO 9141 while your tracker only understands CAN.

2. Battery keeps draining?

So your GPS tracker is killing your car battery? Annoying, right? The good news is this usually isn’t about the protocol at all. Battery draining is about how much juice the tracker is sipping when your car is parked. Here’s what to look for:

• Check for sleep mode: A good tracker should have a low-power or sleep option when the ignition is off.
• Watch idle draw: Some budget devices keep pinging non-stop, even when you’re not driving.
• Upgrade if needed: If there’s no sleep setting and your battery keeps dipping, and it’s a sign of a poorly built tracker.

The fix is simple, either tweak the settings, or if that’s not an option, move up to a better-quality GPS tracker that doesn’t leave you stranded with a dead battery.

3. Tracker Shows Speed but Nothing Else?

Frustrating, right? The tracker powers up, you see speed data, but everything else looks blank.

That usually points to unsupported PIDs. Your car only shares the basics, like speed, while things such as fuel level, RPM, or coolant temperature stay locked away by the manufacturer. A quick scan with an OBD2 app or tool will confirm exactly which PIDs your vehicle makes available.

So you’ll know whether the issue is your car or the tracker.

4. Disconnects randomly?

Sometimes that’s just the ugly truth of cheap builds. Low voltage, bad connectors, or flimsy plastic housings can cause dropouts. Don’t always blame the protocol here, sometimes the tracker itself just isn’t up to the job.

Not every hiccup is about protocols. Sometimes it’s your car, sometimes it’s the tracker, and sometimes it’s just a mismatch. Knowing the difference is what saves you time, money, and a lot of cursing under the dash.

Stiil figuring out, why is my OBD port not working? Read our step-by-step troubleshooting guide.

Final Thoughts

So here’s the takeaway, my friend: protocol equals compatibility and it's the whole game. If your car and your GPS tracker aren’t speaking the same “language,” nothing’s happening. Dead silence.

The good news is the most cars and trucks built in the U.S. after 2008 are easy. 

They all run on CAN, and nearly every OBD2 tracker understands it. Plug in, open the app, and you’re rolling. The things get tricky if you have the older vehicles like pre-2008 rides might be chatting in J1850, ISO 9141, or K-Line.

Some trackers still get along with those, but plenty don’t and the when people waste money and end up frustrated. EVs, hybrids, big rigs are the same deal but with even more curveballs. They sometimes use entirely different protocols like J1939, so here's why I always suggest, check first, and then buy second. 

Year → pins → tracker spec sheet. 

That little routine saves you from a lot of headaches (and a few choice words yelled under the dash).

At the end of the day, this isn’t rocket science. You just need to know what language your car speaks and make sure your tracker understands it. Do that, and you’ll avoid the silent treatment and get the real-time tracking you paid for.

And hey, if you don’t feel like playing protocol detective? Grab a universal OBD2 GPS tracker that already works with most U.S. cars. That way you just plug it in, sit back, and let the tracker do its thing.

Ready To Protect Your Car?

Skip the guesswork. The Konnect OBD GPS Tracker gives you 3-sec real-time tracking, free shipping, and U.S. tech support.

👉 Check Out the Konnect OBD GPS Tracker here & Get Additional $10 OFF
Plug in, track fast and stress less.

Author Disclosure

Written by Ryan Horban, GPS Tracking Expert (15+ Years of Experience)

Over the past 15 years, I’ve helped everyone from parents and pet owners to fleet managers and small business teams choose GPS solutions that actually work.

Whether it’s tracking a car, a child, or an entire fleet, my focus is on simple, legal, and effective setups that protect what matters, without the tech headaches.

I’ve worked hands-on with real users, tested dozens of devices, and know what truly works in the real world.

👉 Connect with me on LinkedIn →

FAQs: OBD2 Protocols & GPS Tracker Compatibility

1. How do I know if my car uses CAN or another OBD2 protocol?

Most U.S. vehicles built from 2008 onward use CAN, no exceptions. If your ride is older, you’ll need to check.

• Pins 6 & 14 are wired is CAN.
• Pins 2 & 10 are wired for J1850.
• Pin 7 (with or without 15) means ISO 9141 or K-Line.

A simple scan tool or app can confirm it instantly if you don’t feel like crawling under the dash.

2. Will an OBD2 GPS tracker work in my pre-2008 car?

Here’s the tricky part: it depends on your car’s protocol. Older Fords and GMs often use J1850, while many Asian and European brands leaned on ISO 9141 or K-Line.

Some GPS trackers still support those, but most new devices are built for CAN. So, checking your vehicle year and the tracker’s spec sheet before you buy is the difference between “works perfectly” and “won’t connect at all.”

3. Why does my GPS tracker plug in but not connect?

That’s almost always a protocol mismatch.

If your car speaks J1850 or ISO 9141 but your tracker only understands CAN, they’ll never talk to each other. A quick protocol check clears up the mystery fast  and saves you from thinking the tracker’s broken when it’s not.

4. Can OBD2 trackers drain my car battery?

Yes, some do and it’s usually the cheap ones.

• Look for a tracker with sleep mode or low-power settings.
• Avoid devices that keep pinging nonstop when the ignition is off.
• Upgrade if your current tracker has no power management at all.

A good-quality tracker won’t leave you with a dead battery.

5. Do electric cars and hybrids use OBD2 protocols?

Some do, but many don’t share as much data through OBD2 as gas cars. 

EVs and hybrids often run different standards or restrict what you can see. This is the big reason why I always tell people: if you’re driving a Tesla, Prius, or any hybrid/EV, confirm with the tracker provider before buying. Saves a lot of frustration.

6. What’s the safest OBD2 GPS tracker for U.S. cars?

For most drivers, you want something universal, CAN-ready, and tested across multiple brands. That way you’re not gambling with compatibility.

One more thing? Look for U.S.-based support and a tracker with a proven track record, because when you do run into questions, talking to a real person who understands U.S. vehicles makes all the difference.