TPMS Basics

What is the difference between direct and indirect TPMS?

Direct TPMS uses a pressure sensor in each wheel that reports by radio, while indirect TPMS uses the ABS wheel speed sensors to detect a tire turning faster because it is low.

Why does the TPMS light flash and then stay on?

Short answer: A light that flashes for about a minute and then stays solid usually means a system fault, such as a dead sensor or missing ID, rather than low pressure.

Most vehicles follow a common pattern. A solid TPMS light means one or more tires are below the warning threshold. A flashing light at startup followed by a solid light usually means the system has a malfunction it cannot resolve.

Common causes include a sensor with a dead battery, a sensor that was damaged during tire service, a wheel or spare without a sensor, a replacement sensor that was never programmed or relearned, or a receiver or module fault.

Use a TPMS tool to trigger each sensor and read its ID, pressure and battery status. A sensor that does not respond is likely dead or missing. Then use a scan tool to read TPMS codes and compare the IDs stored in the vehicle with the IDs you read at the wheels. Replace or program sensors as needed and perform the relearn procedure.

Why is my TPMS light still on after I set the tire pressures?

The system may need time driving to update, a relearn procedure, or it may be reporting a failed sensor, a missing sensor ID or a spare tire sensor; a TPMS tool shows which.

Do I need a TPMS relearn after a tire rotation?

Short answer: It depends on the vehicle; systems that display pressure by wheel position often need a relearn after rotation so the readings show at the correct corners, while others relearn automatically.

Some vehicles show only a single warning light and do not care which sensor is at which corner. Others display each tire's pressure by position, and after a rotation the module may show the right-front reading at the left-rear unless the positions are relearned.

Relearn methods vary: automatic while driving, a stationary procedure using a TPMS tool to trigger each sensor in a set order, or an OBD relearn that writes the sensor IDs directly to the module. Service information or the TPMS tool's vehicle lookup lists the correct method.

Doing the relearn as part of every rotation avoids a return visit when the customer sees wrong positions. Raise and support the vehicle safely on a lift or with jack stands rated for its weight when wheels are removed, and torque the lug nuts to specification.

How does TPMS work with a second set of winter wheels?

Short answer: Winter wheels need their own sensors and the vehicle must learn those sensor IDs each time the wheel sets are swapped, unless the sensors are programmed to copy the original IDs where the tool supports that.

A direct TPMS module only recognizes the sensor IDs it has stored. When a customer switches to winter wheels, the module sees new IDs and sets a warning unless the new sensors are learned.

There are two common approaches. One is to fit sensors to the winter set and perform a relearn at each seasonal swap. The other uses programmable sensors that can be cloned to copy the IDs from the summer sensors, so the module sees the same IDs. Cloning support depends on the sensor and tool, and both sets must never be on the vehicle at the same time.

Label the wheel sets and record the sensor IDs for the customer file. Raise the vehicle on a properly rated lift or with jack stands, never just a jack, and torque wheels to specification.

Is it safe to keep driving with the TPMS light on?

Short answer: A TPMS light means at least one tire may be underinflated or the system has a fault, so check tire pressures as soon as safely possible rather than ignoring it.

A solid TPMS light usually means one or more tires are below the warning threshold. Underinflated tires wear faster, use more fuel and can overheat, which raises the risk of a tire failure.

Pull over when it is safe, check all tires with a gauge, and inflate them to the placard pressure. A flashing light that then stays on usually signals a system fault, such as a sensor that is not reporting.

Never rely on the light alone to judge tire condition. Check pressures regularly with a gauge, and have a shop diagnose a light that stays on after the tires are correctly inflated.