These instructions apply to the Lexus RX Mk4 (AL20) 2015-2022.
For other models, please choose your vehicle here.
If the tyre-pressure warning has come on in your Lexus RX (2015–2022) after you’ve adjusted the pressures or changed a wheel, you reset the monitor with the TPMS SET button. Here’s how.
That amber horseshoe-with-an-exclamation-mark symbol is the tyre-pressure monitor telling you it has seen a pressure it isn’t happy with. On the RX Mk4 it is a routine part of ownership rather than a sign that something has failed: it most often appears on the first cold morning of autumn, after a garage has topped the tyres up, or once you’ve rotated the wheels or fitted a winter set. Once the pressures are correct again, the light only clears when you tell the system to memorise the new baseline — which is exactly what the SET button does.
How TPMS Works on the RX Mk4
This generation of RX uses a direct system: each wheel carries its own battery-powered sensor at the valve that radios its real pressure to the car. Because the readings are absolute rather than inferred from wheel speed, the monitor knows which corner is soft — but it also needs to be re-taught your chosen cold pressures whenever they change, otherwise it keeps comparing live values against the old stored figure and flags a fault. The SET button writes the current pressures in as the new reference; a short drive lets every sensor check in.
First, a Few Checks
- Set the tyres cold — parked for a few hours, or driven less than about a mile — because pressure climbs as the tyres warm.
- Use the figure on the placard in the driver’s door shut; the RX often lists a slightly higher setting for a full load or motorway running.
- Don’t forget the spare if your car carries a full-size wheel with its own sensor.
- Park on level ground with the vehicle stationary before you begin.
- You only need the ignition on — the hybrid or petrol powertrain does not have to be running.
Resetting the System
- Park level and set all four tyres to the correct cold pressures (placard in the driver’s door shut).
- Switch the ignition on (you don’t need to start the engine/hybrid system).
- Press and hold the TPMS ‘SET’ button (low on the dash near the steering column) until the TPMS warning light blinks (typically three times), then release.
- The system learns the current pressures as the new baseline; it finishes after a short drive.
If the Warning Won’t Clear
- Recheck every corner with a gauge — a single tyre a few psi low keeps the light on and blocks the relearn.
- Hold SET until the light actually blinks; letting go too soon cancels the registration and nothing is stored.
- Drive for several minutes after pressing SET so each sensor wakes and transmits — the light may take a mile or two to go out.
- Remember to re-store the pressures after any wheel swap, including moving to winter wheels or back.
- Check that a space-saver or spare you fitted is at its own (usually higher) pressure.
- A slow puncture will bleed a tyre down again within hours — if one corner keeps returning, have it inspected.
- After several years a sensor battery can go flat; that corner then reads nothing and the reset won’t take until the sensor is renewed.
Once It’s Done
Once the pressures are correct and the SET registration has taken, the warning light goes out and stays off for the rest of your journeys, only returning if a tyre genuinely drops or the weather turns sharply colder. There is no separate confirmation beep — the light simply extinguishing is your all-clear.
Frequently Asked Questions
How do I reset the tyre pressure light on a Lexus RX?
Set the pressures, switch on, then press and hold the TPMS SET button until the warning light blinks.
Where is the TPMS SET button?
It sits low on the dashboard near the steering column, often below or beside the instrument-cluster controls. The exact position varies by trim and market, so your handbook shows the precise spot; look for a small button marked ‘SET’ once the correct pressures are in.
Why won’t the warning clear after I’ve set the pressures?
Nearly always because one tyre is still a little below the placard figure, or the SET button wasn’t held long enough for the light to blink. Re-gauge all four (and the spare if it has a sensor), correct any that are low, then repeat the hold-and-release and drive a short distance.
Do I need to reset TPMS after rotating or changing wheels?
Yes. Because the RX stores your chosen cold pressures as its reference, any time you swap wheels, fit winter tyres, or rotate them you should confirm the pressures and run the SET procedure again so the monitor compares live readings against the right baseline.
Could cold weather trigger the light on its own?
It can. Tyre pressure falls by roughly 1–2 psi for every 10°C drop, so a cold snap can push a correctly-set tyre below the threshold overnight. Top the tyres back up to the placard figure while cold and reset; the light should stay off once they’re back in range.
Do I need a tool?
No for a normal reset; a tool is only needed if a sensor is replaced.
If the warning came on with other lights, decode the code on autodtcs.com.
Independent guide — not affiliated with Lexus. Always follow your official service manual and safety precautions. Read our full disclaimer.