Tire Pressure Monitoring System
All modern Aston Martins are equipped with a tire pressure monitoring system (TPMS). It constantly monitors the air pressure in each tire and creates a warning if it detects low pressure in any of them.
As of this writing, there are two systems in use. The early V8 Vantage was equipped with a system from SmartTire. A few years later that was replaced by a system from Beru. The Beru system is typically easier to manage as the sensors are less expensive, so the information below will pertain specifically to the SmartTire system. They're mostly identical, from a user's point of view, so don't worry if you have the Beru system, the information here will still apply.
The system consists of a central module and four sensors. The central module is mounted under the glove box and connects to the car's interior wiring harness.
Each wheel has one of the four sensors, which allow the pressures to be read independently. The sensors are in the wheels' valve stems and have colored rings around them, which then correspond to a color marking on the central module. When a sensor reads a low pressure, the light for that sensor will illuminate on the module and a warning will be sent to the LCD screen on the gauge cluster.
To clear the warning, you can press the 'Read' button on the main console, but be warned it'll come back so long as the root cause of the warning isn't fixed.
Faults and Fixes
There are three things that can cause a Low Pressure warning and each has a different fix. The fault signal is the same regardless of the cause, so you'll have to check the affected tire to figure out what's wrong.
First is the obvious one: a tire has low air pressure. This can be caused by damage to the tire - usually a puncture. Once you repair or replace the damaged tire, the fault should go away.
The second cause is the environment. Air pressure is heat sensitive. As air in a tire gets colder, its pressure goes down. Temperatures for cold tires drop quite a bit when winter comes around in regions of the world that experience true winter. So you may not have had any tire pressure warnings, nor any damage to your tires, but the sensors will detect a lower pressure and give you a fault warning. The warning will go away as the tires heat up and the air pressures in them increase. Fixing this is just a matter of adding some air to each of the tires so they have a higher air pressure when cold.
The third cause is a thorn in the side of Aston Owners everywhere. The sensors in each wheel have a battery that will eventually die. When a sensor's battery dies, it triggers a fault that shows the same Low Pressure warning even though the tire's air pressure is perfectly fine. There are a couple of options for dealing with a dead sensor.
Replace the sensor. You'll need to replace the entire sensor as the battery is embedded in it and not made to be replaceable. I've heard of people digging the batteries out, but I've never tried it and it's possible to damage the sensor. Keep in mind that if the battery in one sensor has died, the others are likely to follow soon.
Disable the system. If you don't want to spend the money to replace the sensor(s), you can just disable the TPMS entirely. Keep in mind that by doing this, the system will not be able to alert you in case of an actual low-pressure situation.
Disabling the TPMS
WARNING: Disabling the Tire Pressure Monitoring System will prevent it from alerting you in the event of low air pressure in your tires.
The central module used in the early V8 Vantage had a three-wire connection to the car's interior wiring harness. For cars with a three-wire connection, you can simply unplug the central module and leave it unplugged.
Sometime around late MY07, a fourth wire was added to that connection to prevent people from unplugging the central module to disable the TPMS. If the central module is disconnected, it will automatically trigger a fault and give you the tire pressure warning. Using our TPMS Fault Defeat will allow you to disable the TPMS without unplugging it - it keeps the central module plugged in so you won't get a warning from disconnecting it, but prevents fault signals from getting from the central module to the gauge cluster.