2004 BMW 325Ci Tire Pressure Monitoring System Relearn Cost

Vehicles with the added benefit of tire pressure monitoring are able to tell the driver when the air pressure in a tire is too high, too low, and, in some vehicles, what the exact tire pressure is at all times. Manufacturers use sensors in the wheels to communicate wirelessly to the tire pressure monitoring system control module, and this module will illuminate the warning light when there is a tire air pressure issue. When the TPMS sensors inside the tires fail to communicate, are replaced, or the battery for the vehicle has been disconnected, a relearn may need to be completed for the system to resume operation.

The tire pressure monitoring system (TPMS) control module will receive information from the tire pressure monitoring sensors at all times the vehicle is on. In most vehicles, the only purpose of the TPMS control module is to illuminate the TPMS warning light when the tire is under or overinflated. The sensors in the tire are incorporated at the air stems, and automatically adjust their output signal as the pressure in the tire changes.

When a relearn is needed, for any reason, the TPMS warning light will illuminate, and many vehicles will display a message relating to the TPMS system being inoperative or loosing communication. It is important to keep a watchful eye on tire pressures when this system is having issues because there is no warning available for underinflation or overinflation of the tires.

The TPMS warning light comes on all the time, but that does not mean it should be ignored. The light is designed to give you fair warning of deflation before damage is done to the tire or wheel, and to prevent unsafe driving when a tire goes flat. Anytime the light comes on, pull over and check the air pressure as soon as it is safe to do so. If the tires are inspected regularly, the TPMS system never needs to be repaired, however, if the TPMS system is relied upon to guide maintenance, ignoring the situation may lead to a flat tire.

As stated before, this occurs all of the time. In fact, this may be the most commonly seen warning light on the instrument cluster, but it does not always require the sensors to be relearned. In nearly all cases the light will go off a few minutes after adjusting the air pressure in all four or six tires. This leaves a relatively small number of times where the TPMS sensor(s) must be relearned or replaced. Again, this is common, especially if the roads local to the vehicle have potholes and bumps, and all vehicles with TPMS will eventually have the sensors replaced. The sensors must be relearned after each replacement.

After checking the air pressure, the technician will need to connect a diagnostic scan tool to test the wheel sensors first. In some vehicles, the sensors will not set an OBD-II code directing the technician to the faulty tire pressure sensor, and those must be checked manually. The tires can be inflated and deflated one at a time, and the sensor that does not register the change is faulty, or a wireless scanner can be used to attempt to contact the individual sensors at each wheel. If the sensors are working properly, but the control module does not recognize the TPMS tire pressure sensors, a relearn will be attempted.

Performing a relearn for tire pressure sensors is an electronic function that reintroduces the TPMS control module to the TPMS tire pressure sensors. In order for the sensors to communicate to the control module, the control module must register those sensors as part of the vehicle, otherwise TPMS sensors from different vehicles would communicate with one another when in close proximity. Most sensors will relearn on their own. After driving the vehicle for a few miles, the TPMS warning light should turn off, and the sensors are relearned. However, some models require the sensors to be introduced "formally" through the use of a professional scan tool which can access the TPMS control module. The later is more rare.

We always recommend contacting the repair center where the tires were last installed. Although the tire pressure sensors are fairly inexpensive, it is best to use the warranty if purchased. If a relearn is required, the repair facility may not even charge for the service, may charge a reduced rate, or may advise driving the vehicle after changing tire pressures.

It is essential to understanding where to locate the tire pressure information for the vehicle you drive in the event that you need to check, inflate, or deflate the tires. The information is likely posted on the driver door frame, inside the fuel tank lid, or in the owner's manual. Inflating a tire to the maximum allowable limit printed on the sidewall will be incorrectly overinflated every time.

Checking the air pressure in the tires is something anyone can do, and this solves the majority of issues arising with the TPMS warning lamp However, if a tire goes flat without the TPMS warning light being displayed, or the warning lamp does not turn off with correct pressure, diagnosis will need to be performed with a professional scanner. If the tire pressure sensors must be relearned through a professional scan tool, it is much more cost effective to have that service done by a tire or repair center.