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2018 Chrysler 300 OBD Live Data: How to Bypass the SGW with a 12+8 Connector
If you’ve ever plugged a scan tool into a 2018 (or newer) Chrysler 300, Dodge Charger, Jeep Grand Cherokee, or any other late-model Stellantis vehicle and gotten nothing but stone-walled basic OBD codes, you’ve met the SGW.
Welcome to one of the most frustrating changes the modern car industry has ever rolled out for independent shops and DIY mechanics. The good news is there’s a clean, legal, manufacturer-approved way around it. The bad news is it’s not free and it’s not obvious. Here’s the full breakdown from John at Johnny on the Go on a 2018 Chrysler 300.
What Is the SGW?
SGW stands for Security Gateway Module. Stellantis (formerly FCA, the parent company of Chrysler, Dodge, Jeep, Ram, Fiat, and Alfa Romeo) introduced the SGW on most of its vehicles starting in late 2017 and 2018 model years. The same module also appears on certain Nissan products from a similar era forward.
Its job is to sit between your OBD-II port and the rest of the vehicle’s CAN bus network. Think of it as a firewall for your car. Without it, anyone who plugs a scan tool into the OBD port could read live data and, more importantly, write to vehicle modules. That includes things like turning off airbags, reflashing modules, programming keys, and disabling antitheft systems. The SGW was added because automakers (and federal regulators) decided that level of open access wasn’t safe anymore in an age of car hacking.
The result for everyday repair work: a generic OBD-II reader still pulls basic codes (the OBD-II standard is federally protected for emissions purposes). But anything beyond that, two-way communication, live data streams from non-emissions modules, bidirectional control, ABS bleeds, key programming, electronic parking brake service, you name it, all of that gets blocked at the gateway.
That’s why a lot of techs plug in their old scan tool, see “communication error” or “limited data,” and start swearing.
The 12+8 Connector: How You Get Past the SGW
To do real diagnostic work on an SGW-equipped Stellantis vehicle, you need three things:
- A 12+8 SGW bypass connector. This is a physical Y-cable adapter that plugs into the OBD-II port AND into a separate 8-pin secure connector behind the dash. The 8-pin port is the “back door” that Stellantis specifically left for licensed scan tools.
- A compatible aftermarket scan tool with an active subscription. Tools that support FCA/Stellantis SGW unlock include Autel Maxisys with the SGW package, Launch X-431 with the FCA module, Snap-on, Bosch, Topdon, Thinktool, and a few others. The tool itself isn’t enough. You need an active subscription that includes Stellantis SGW authorization.
- An AutoAuth account. AutoAuth is the third-party gateway that actually authenticates your scan tool with Stellantis’s servers. You pay a yearly fee for a personal or shop account. Once active, your scan tool talks to AutoAuth, AutoAuth talks to Stellantis, and the SGW unlocks for that session.
So the math is: 12+8 cable, plus scan tool + active scan tool subscription, plus AutoAuth subscription, plus a Wi-Fi connection at the vehicle so the tool can authenticate online. All of that adds up to real cost. There’s no shortcut. There’s no “free SGW unlock.” Anyone selling you one is selling you grief.
Where the 8-Pin Port Lives on a 2018 Chrysler 300
On the 2018 Chrysler 300, the 8-pin secure connector is hidden behind the lower trim panel under the steering column on the driver’s side, right next to (or just above) the standard OBD-II port. To access it:
- Pry the lower side trim panel loose. It’s held by a couple of clips and either two 8mm bolts or two Phillips-head screws depending on your specific vehicle. (Stellantis sometimes mixes fastener types within the same model year, so be ready with both.)
- Drop the panel down. Mind the wiring harnesses behind it.
- Locate the 8-pin port. It’s a smaller rectangular connector tucked just behind where the trim panel was sitting.
- Plug in the 12+8 adapter. The 12-pin side goes into the standard OBD-II port. The 8-pin side goes into the secure connector.
- Connect your scan tool to the adapter and proceed as normal. Once authenticated through AutoAuth, you have full bidirectional access.
When you’re done, unplug everything, snap the panel back into place, and you’re set. Five minutes of work once you’ve done it a few times.
Why John Carries This Setup on Every Stellantis and Nissan Job
This isn’t a “we’ll order the part and come back” situation. We carry the 12+8 SGW adapter, an active AutoAuth subscription, and an FCA-authorized scan tool in the Mobile Command Center on every call. That means we can do real mobile diagnostics on a 2018+ Chrysler 300, Dodge Charger, Jeep Grand Cherokee, Ram 1500, Fiat 500X, or pretty much any Stellantis product without sending you to the dealer.
The same applies to Nissan products that adopted similar gateway architecture. Same workflow, same tooling, just a different scan tool profile.
For an independent customer, this changes the math in a big way. Most independent shops in Central Florida either don’t carry the SGW unlock setup or only run it on certain bays at the shop. Mobile shops almost never carry it. We do. That’s the whole point of running a Mobile Command Center instead of a regular service van.
Common Things Customers Need This For
A 12+8 / SGW bypass isn’t a luxury. It’s required for almost any non-trivial repair on a modern Stellantis vehicle:
- Live data on engine, transmission, ABS, body control, climate, infotainment, and security modules
- ABS module bleeding and brake system service procedures
- Electronic parking brake retraction (so you can do brake pads on a Jeep Grand Cherokee)
- TPMS sensor relearn
- Steering angle sensor calibration
- Throttle body relearn
- Battery registration after replacement (yes, modern Chryslers want the new battery registered)
- Key fob and immobilizer programming
- Module reflashes
- Reading and clearing codes from non-emissions modules
If a “regular” scan tool tells you “no communication” or only shows generic emissions codes, you’re hitting the SGW wall. The fix is the bypass setup, not a different scan tool brand.
A Heads-Up: The CAN Bus Module Itself Can Fail
While we’re on the topic, the CAN bus module on these mid-decade Stellantis vehicles has its own reputation. They go bad. We see it often enough to mention. If your 2018-2020 Chrysler / Dodge / Jeep is showing weird intermittent communication faults across multiple modules, sudden electrical gremlins, dash warnings that don’t match symptoms, or modules that “drop off” the bus and come back, the SGW or the surrounding bus hardware itself may be the culprit, not the individual modules it’s gating.
That kind of diagnosis takes the right scan tool, the right cable, and someone who’s seen it before. We’ve seen it before.
DIY vs. Calling Us
If you’re a DIYer who works on a few cars, the cost of buying into a Stellantis-capable scan tool, a 12+8 cable, and a yearly AutoAuth subscription is real. Last we checked, you’re looking at $200-$300 minimum for a basic SGW-capable scanner setup, plus $50-$100 for AutoAuth annually, plus the tool subscription on top. For one personal car, the math doesn’t always work out.
For one or two diagnostic visits a year, calling Johnny on the Go is significantly cheaper than buying the toolkit yourself. We come to you, run live data, run bidirectional tests, perform the repair, and report it to your Carfax history. No tow, no shop bay wait, no buying tools you’ll use twice.
If you’re a small shop that’s been turning away Stellantis work because of the SGW headache, we’ll happily take those referrals.
Carfax Reporting on Diagnostic Work
This is worth saying every time: every service we perform, including diagnostic visits, gets reported to your vehicle’s Carfax record. So when this 2018 Chrysler 300 owner goes to sell, the next buyer can see a documented professional diagnostic visit instead of a question mark. That’s resale value protection that costs the customer nothing extra.
We Cover All of Central Florida
Johnny on the Go is a fully mobile auto repair shop based in Orlando, Florida. We cover Orange, Seminole, and Osceola counties. That includes Orlando, Maitland, Winter Park, Lake Mary, Sanford, Lee Vista, Lake Nona, Altamonte Springs, Longwood, Casselberry, Kissimmee, St. Cloud, Celebration, and Poinciana.
Mobile diagnostics, brake service, batteries, tire rotations, roadside assistance, fleet maintenance, oil changes, SGW-protected diagnostics on Stellantis and Nissan vehicles, all done at your location, all reported to Carfax.
📞 Call (321) 466-5222 📅 Book a service online
We bring the SHOP to YOU.
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