Your scanner will not connect, the link keeps dropping or the readings look wrong? Often the culprit is neither the adapter nor the car's electronics but the OBD diagnostic port itself. It sits low under the dashboard where dust, grit from shoes, crumbs and moisture collect, and the pins oxidise over time.
A dirty or corroded port makes poor contact: communication errors, incorrect readings and, with permanently plugged-in adapters, even a risk of damage. Cleaning it takes about ten minutes.
What you will need
Important: Never use metal objects, needles or abrasive paper on the pins: you can bend or scratch them and short them together. Do not use lubricants or products that leave a film.
Step 1
Switch off the car and unplug the scanner
The engine and ignition must be off and the key removed. If a diagnostic adapter or tracker is plugged into the port, disconnect it. Wait a few minutes for the electronics to go to sleep.
Step 2
Locate and inspect the port
The OBD socket is usually under the steering wheel, near the fuse box or at the bottom of the dashboard, sometimes behind a small cover. Use a torch.
Check the pins for dust, hairs, moisture and green or white corrosion. If the port is very dirty, do not plug anything into it until it has been cleaned.
Step 3
Remove loose dirt
With a soft dry brush, gently sweep dust and debris out of the socket, brushing along the pins rather than across them. A light puff of air helps remove fine particles.
Step 4
Treat the pins with contact cleaner
Shake the can and give a short spray of WD-40 Specialist Contact Cleaner into the socket from 10-15 cm. It dissolves greasy deposits, oxidation and condensation and is safe on most plastics and sensitive electronics.
For heavy deposits, work gently with a soft brush and spray again. Mop up any excess around the socket with microfibre, without pushing cloth between the pins.
Step 5
Let it dry and test the connection
The cleaner evaporates within minutes without residue. Wait until the socket is completely dry before switching on the ignition.
Clean the plug on your scanner with the same WD-40 Specialist Contact Cleaner while you are at it. Connect the adapter and check that the link is stable.
Tip: If the port has no cover and the adapter is not permanently fitted, close it with a plastic dust cap. That keeps out dust and moisture from the mats, especially in winter when snow gets carried into the car.
What next
Check and clean the OBD port once a year or whenever the scanner starts playing up. The same WD-40 Specialist Contact Cleaner works on headlight connectors, sensors and terminals under the bonnet.
These uses come from the experience of WD-40 users in many countries. Always follow the instructions and warnings on the product label.
More guides in «How to use».