Mercedes-Benz GLA OBD-II Port Location
Reviewed/Verified by:
Do you need to connect your OBD-II scanner to your Mercedes-Benz? This guide provides a step-by-step process to find the OBD II port in the Mercedes-Benz GLA.
At a Glance
- Location: under the dashboard on the driver’s side, above the brake pedal.
- It sits behind a small cover just to the right of the red hood release lever.
- Pull the cover down to expose the 16 pin port.
- Plug the scanner in with the ignition off, then switch it on.
- A scanner such as the YOUCANIC UCAN-II Pro plugs into this port for full system scans, live data and Mercedes service resets on supported models.
Procedure
- Unlock the car using the vehicle’s key fob and open the door on the driver’s side.
- Look under the dashboard on the driver’s side. Below the dashboard, find the brake pedal’s location and the hood release lever to help you easily find the OBD 2 port cover.
- Find the OBD 2 port cover. Above the brake pedal, you will find the OBD port cover. You can also locate the OBD port cover at the right side of the hood release/red release lever.
- Open the OBD port cover by pulling it down. When the OBD II port cover is open, you will see the port to attach or connect the OBD II reader. The On-Board Diagnostic II port is used to access the vehicle’s computer for various tasks, such as emission tests and diagnostics.
The YOUCANIC UCAN-II Pro is a perfect example of an OBD-II scanner for troubleshooting problems with your GLA. This powerful device can read and clear fault codes from the systems it supports on the GLA, perform bidirectional tests, perform maintenance and repair resets, and perform many more professional-grade functions that can help you determine the cause of the problem.
Turn the ignition fully on before scanning
Most modules only wake up and answer a scanner with the ignition in the run position. On a GLA with keyless start, press the start button twice without touching the brake pedal to reach ignition on without cranking the engine. Connecting with the car asleep, or only in accessory, makes the scanner report modules as missing that are perfectly healthy, which is the single most common reason a scan looks alarming when nothing is wrong.
🔧 Find out what is actually wrong before you pay someone to guess
Dealer level diagnostics at home with the YOUCANIC UCAN-II Pro.
- ✔ Covers most makes and models, including many luxury brands. Send us your VIN and we will confirm your car before you order
- ✔ Reads every module, not just the engine, so you find the faults a basic reader says are not there
- ✔ Commands the car: test a fan or pump, bleed ABS, retract an electronic parking brake, register a battery
- ✔ No subscriptions. Free lifetime updates, so the price you pay is the whole price
- ✔ Backed by real mechanics in the USA you can email before and after you buy
Featured in The Wall Street Journal
If the scanner will not power up
The port takes battery power through a fuse, usually shared with the cigarette lighter or an accessory socket, so if neither the lighter nor the scanner works you have found the problem. Check that fuse before assuming the port or the tool has failed. A quick confirmation is to measure between pin 16 and pin 4 of the connector, which should read battery voltage with the ignition off.
A basic code reader sees very little on a Mercedes
An inexpensive reader talks to the engine module only, which is why a GLA with a warning light on the dash so often reads as having no faults. Everything interesting on these cars lives elsewhere: the transmission, SBC or ABS, the SRS module, the SAM units and the climate control. If a light is on and the scanner shows nothing, you are looking in the only place the fault is not.
Leave nothing plugged in when you park
Some scanners and the cheap Bluetooth dongles people leave permanently connected keep drawing current after the car is locked, and a few keep modules awake. On a car that already has a modest battery and a lot of electronics, that is enough to produce a dead battery and a screen full of unrelated warning messages after a few days standing. Unplug the tool when you have finished.
What to do next: the GLA job that actually needs the port
For most GLA owners the reason to care about this connector is not a check engine light. It is the rear brakes. The electronic parking brake holds the rear calipers, and it has to be put into service position before the pads will come out. There is no mechanical override to fall back on.
- Decide first whether your job touches the rear brakes. If it does, you need a tool that can retract the parking brake actuators, and that is a command sent to the car rather than a code read from it.
- Scan all modules before assuming the worst about any warning message. Mercedes spreads faults across a long module list and a basic reader sees almost none of it.
- Check battery condition early. On these cars a weak battery produces a run of unrelated dash messages that disappear once the supply is healthy.
- Clear codes only after the repair, then drive it and see what returns. A code that comes straight back is telling you the fault is still live.
Our guide on Mercedes-Benz Release Electronic Parking Brake to Change Pads covers the sequence in full.
The YOUCANIC UCAN-II Pro performs the parking brake service function and reads the whole module list, with a seven day rental if you only need it for a brake job. Function support varies by model and year, so email support with your VIN before ordering.
When you do not need a tool at all
Front pads only, a tracker installation, or simply reading an engine code. None of those require anything past the socket.
Frequently Asked Questions
Where is the OBD2 port on a Mercedes-Benz GLA?
It is under the dashboard on the driver’s side above the brake pedal, behind a small cover just to the right of the red hood release lever.
How do I turn the ignition on without starting a keyless GLA?
Press the start button twice without touching the brake pedal. This reaches ignition on without cranking the engine.
Why does my scanner show modules as missing?
Most modules only respond with the ignition in the run position. Scanning in accessory mode or with the car asleep makes healthy modules look missing.
Can a basic code reader scan a Mercedes GLA?
A basic reader only sees generic engine codes. To read modules such as ABS, airbag and transmission you need a full system scanner.
Related Guides
- Mercedes-Benz Multiplexer Models Reference (38-Pin OBD Port): Listed by Class/Chassis
- Mercedes-Benz GLA-Class (X156) Oil Service Reminder Reset
- Replace Front Turn Signal Light Bulb Mercedes-Benz GLA-Class 2014 to 2019
- Diagnose Warning Lights Mercedes-Benz GLA-Class X156 2014 to 2019
