Is your OBD2 device failing to connect or power up? A non-responsive OBD2 port can be a frustrating issue, especially when you need to diagnose a car problem or use a plug-and-play device. This guide will walk you through the common causes of an “Obd2 Port Not Reading” issue and provide simple steps to troubleshoot and potentially fix it yourself.
The first sign that your OBD2 port might not be reading is when you plug in a device, like a diagnostic scanner or a vehicle tracker, and it doesn’t power on. Most plug-and-play OBD2 devices are designed to beep or light up when they receive power from the port. If you’re met with silence, it’s a clear indication that power isn’t flowing as it should.
Let’s start with the most straightforward checks and move towards more detailed troubleshooting.
Initial Checks: Connection Issues
Often, the simplest solutions are the most effective. Before diving into more complex diagnostics, ensure that the connection to the OBD2 port is secure.
If you’re plugging your device directly into the OBD2 port, unplug it and firmly reconnect it. Sometimes, a loose connection is all it takes to disrupt the power supply.
Are you using an OBD2 extension cable with your device? Extension cables can add convenience, but they also introduce more potential points of failure. If you are using an extension cable, try these steps:
1. Check the Cable Connection to the OBD2 Port
- Turn off your engine. This is a safety precaution before working with vehicle electronics.
- Disconnect the extension cable from your car’s OBD2 port.
- Wait for about 5 minutes. This brief pause can help reset any temporary electrical glitches.
- Reconnect the cable firmly to the OBD2 port.
- Listen for a beep from your OBD2 device. If you hear a beep, it indicates that the unit is now receiving power, and the problem might be resolved.
2. Check the Cable Connection to the OBD2 Device
If the device still doesn’t beep after checking the connection to the OBD2 port, the issue might lie in the connection between the extension cable and your OBD2 device.
- Ensure the engine is off.
- Unplug the OBD2 device from the extension cable.
- Wait 5 minutes.
- Reconnect the OBD2 device to the extension cable, making sure it’s firmly plugged in.
- Listen for the beep. If the device beeps now, the connection was likely the problem.
Testing the OBD2 Device Directly
To rule out any issues with the extension cable itself, it’s a good idea to test your OBD2 device by plugging it directly into the OBD2 port, bypassing the cable altogether.
- Disconnect the extension cable from both the OBD2 port and the device.
- Plug the OBD2 device directly into the vehicle’s OBD2 port.
- Check for the beep. If the device beeps when plugged directly in, this indicates that the extension cable might be faulty or have a blown fuse (if it has one).
Inspecting the Cable’s Fuse
Some OBD2 extension cables come with an inline fuse to protect your devices and car’s electrical system. A blown fuse in the cable is a common reason for an OBD2 port not reading.
- Locate the fuse holder on the extension cable. It’s usually a small, rectangular component with a cap that can be opened.
- Open the fuse holder cap to access the fuse.
- Remove the fuse.
- Inspect the fuse. Look for a broken wire inside the fuse. If the wire is broken or the fuse looks blackened, it’s blown and needs replacement.
- Test the fuse with a multimeter for continuity, or simply replace it with a new fuse of the same rating (usually 3A mini-blade fuses, available at auto parts stores).
- With the cable connected to the OBD2 port and the device, insert the new fuse into the fuse holder and close the cap.
- Check if the OBD2 device now powers on.
Checking the OBD2 Port Itself
If you’ve ruled out connection issues, cable problems, and fuses, the next step is to check if the OBD2 port in your car is actually receiving power. For this, you’ll need a digital multimeter.
- Set your multimeter to measure DC voltage.
- Locate pins 16, 4, and 5 on your OBD2 port. Pin 16 is power, pin 4 is chassis ground, and pin 5 is signal ground. You can find OBD2 port pinout diagrams online if needed.
- Connect the red lead (positive) of your multimeter to pin 16.
- Connect the black lead (negative) to pin 4 or 5 (ground).
- Check the voltage reading. You should see approximately 12 volts (or your car’s battery voltage).
If the multimeter shows 0 volts, it means the OBD2 port is not receiving power. The most likely cause is a blown fuse in your car’s electrical system.
Checking Car Fuses Related to the OBD2 Port
The OBD2 port is often fused on the auxiliary circuit, which might be labeled as “cigarette lighter” or “accessory” on your car’s fuse box diagram.
- Locate your car’s fuse box diagram. This is usually found in your owner’s manual or printed on the fuse box cover itself.
- Identify the fuse related to the auxiliary power outlet or cigarette lighter.
- Check this fuse. You can visually inspect it or use a fuse tester or multimeter.
- Replace any blown fuse with a new fuse of the same amperage rating.
- Re-test the OBD2 port voltage with the multimeter to see if power is restored.
- Try plugging in your OBD2 device again.
If, after checking all these fuses, your OBD2 port still shows no power, or if your OBD2 device still isn’t working, there might be a more serious electrical issue, or the OBD2 device itself could be faulty.
Still Having Trouble?
If you’ve gone through all these troubleshooting steps and your OBD2 port is still not reading, it’s time to seek professional help. Contact a qualified mechanic or the support team for your OBD2 device. For vehicle tracking devices, contacting their support is the next logical step.
When you contact support, be ready to provide them with:
- Your vehicle’s make and model.
- The last known time your device was working (if applicable).
- A detailed description of the troubleshooting steps you’ve already taken.
By following these steps, you can systematically diagnose and often resolve the issue of an “OBD2 port not reading,” getting your devices back online and your car diagnostics back on track.
