Why your tire pressure light keeps coming back near the ocean

It is one of the most common things we hear: I filled the tire, the light went out, and now it is back. There is no nail in the tread and the tire looks fine. Living this close to the ocean, the cause is usually not the tire at all.

What the pressure light is actually telling you

Your car has a sensor inside each wheel, mounted on the valve stem. When one reads low, the light comes on. If the light keeps coming back after you fill up, the tire is really losing air, slowly. The question is where it is going.

Salt air is hard on the parts you cannot see

Two places corrode near the coast. The first is the valve stem on the pressure sensor, and the small seal, core and nut that hold it in the wheel. When those corrode, the seal stops sealing and air seeps out around the stem.

The second is the bead seat on an alloy wheel, the ring where the tire seals against the rim. Salt corrodes the aluminum there, the surface gets rough, and the tire cannot seal against it properly. That shows up as a tire that goes down every few days with nothing in the tread.

What actually fixes it

You do not always need a new sensor. What you do need, whenever the tire comes off the wheel, is a new service kit: the valve core, seal and nut that sit between the sensor and the wheel. It costs little and it is the part that fails most often near the water. We replace it every time a tire comes off, so the seal is new.

For a leaking bead, the fix is to take the tire off, clean the corrosion off the bead seat and refit it so it seals again. We do that as part of the job rather than just adding air and sending you away.

If a sensor itself is dead, usually because its battery has run out after years of service, we program a new one to the car.

When the light stays on after you fill up

Some cars need a short drive above about 15 mph before the system re-reads all four sensors and clears itself. If it stays on after that, one sensor is not reporting, and that is worth a look.

Signs it is time to bring it in

• The light comes back within days of filling up
• One tire is always the low one
• A tire loses air with no nail or screw in it
• The light stays on after a drive, with all four tires filled
• You just bought tires elsewhere and now one keeps going down

Bring it to the shop on NE 26 Court and we will find where the air is going. We test each sensor, replace its service kit, clean the bead seat if it is corroded, balance the wheel and set all four pressures before the light is cleared.