A vital part of servicing TPMS is to understand the different components of a TPMS sensor and which roles they play, Which components are replaceable or serviceable.
One of the most important factors of properly servicing tyre pressure sensors is to fully understand all of the different components involved in the sensor’s construction. By doing the following you will also understand why certain components either need to be changed or replaced.
The following details will help you explain the servicing procedure.
A TPMS sensor has 2 main components, the sensor body and the valve stem.
The sensor body is the plastic enclosed part which is mounted inside the tyre. Usually filled with epoxy to keep the moisture away from the electronic components housed inside. Because of this the battery and other components cannot be changed they will require replacement if at fault.
The valve stem is what connects the sensor to the rim. Now this may come in either a Rubber snap-in or an Aluminium clamp-in. They both serve the same purpose to hold the sensor in place and to keep air in the tyre.
Within the valve stem you have either a brass or aluminium valve core, on clamp-in valves you also have a rubber grommet, aluminium nut and sometimes a grommet seat will also be provided to properly seal the sensor.
The component which is most vulnerable to being damaged is the valve stem due to being exposed to all the road salts, dirt from the roads & weather conditions.
A plastic sealing valve cap should be securely tightened to prevent valve damage and galvanic corrosion. For this very reason we recommend that you replace the valves service kit at every tyre change.
A service kit refers to the serviceable components of a tyre pressure sensor.
In the case of rubber snap-in and metal clamp-in valves, this will include the stem. Some variations of TPMS come with the valve stem permanently fixed to the sensor body, Neglecting the service kits can often lead to slow leaks and costly comebacks.
When servicing TPMS, always first check the tell-tale light on the dashboard. If it blinks before remaining solid, it signals that something is wrong with the TPMS system (the sensor body). Either a sensor needs to be relearned to the vehicle, one or more sensors has a dead battery, or an incorrect sensor is installed or improperly programmed to the vehicle’s make, model and year. If the TPMS light turns on and remains solid, it simply means that one or more of the tires are low on air. This could lead to a slow air leak or simply mean that the tire needs to be filled to the vehicle’s recommended placard pressure. Understanding the different TPMS sensor components is imperative to diagnosing and choosing the proper service solution.