A tyre-pressure monitoring system (TPMS) is the reason the little horseshoe-shaped warning light comes on when a tyre is low. Since November 2014 every new passenger car sold in the EU and UK has had one fitted as standard, and a faulty system is now an MOT failure on cars first used from 1 January 2012. So when a sensor battery dies or a sensor is damaged during a tyre change, it needs replacing with one that actually talks to your car. This guide explains how the system works and what to check before you buy.
Direct vs indirect TPMS
There are two kinds of system and only one of them uses sensors in the wheels.
- Indirect TPMS uses the ABS wheel-speed sensors to spot a tyre that is rotating faster than the others because it has lost pressure. There is nothing inside the wheel, so there is nothing to replace — you just reset the system after inflating the tyres. Common on many VW Group, Honda and Mazda models.
- Direct TPMS has a battery-powered sensor inside each wheel, usually built into the valve stem. Each sensor measures the real pressure and temperature and transmits it by radio to a receiver in the car. This is the system that needs replacement sensors.
If your dashboard shows a pressure figure for each wheel, you almost certainly have direct TPMS. If it only shows a warning light with no numbers, check your handbook — it could be either.
Frequency: 315 MHz or 433 MHz
Direct sensors transmit on one of two frequencies. Cars built for Europe, the UK and most of Asia use 433 MHz; cars built for North America and Japan mostly use 315 MHz. A sensor on the wrong frequency will fit the wheel perfectly and never be heard by the car. Imported vehicles are the usual trap: a Japanese-import Toyota or a US-spec Ford needs the 315 MHz sensor even though it is driving on UK roads.
OE, OE-replacement and programmable sensors
- OE sensors are the manufacturer part, sold by the dealer. They work, but they are the most expensive option.
- OE-replacement sensors are pre-programmed clones of a specific OE part number. They are plug-and-play for the vehicles on their fitment list and are what most owners should buy.
- Programmable (universal) sensors are blank until a tyre shop writes the correct protocol into them with a TPMS tool. Useful for workshops that stock one sensor for many cars, but you need the tool and the right software to use them.
Valve type and torque
Sensors come with either a metal clamp-in valve or a rubber snap-in valve. Both work the same electronically; the difference is how they fit the wheel and how they are serviced. Clamp-in valves must be tightened to the specified torque (typically 4–8 Nm for the nut and around 1.4 Nm for the valve core) — over-tightening cracks the stem and is the most common reason a new sensor leaks. The sensor should be fitted by a tyre shop with a torque wrench and a new service kit (seal, nut, cap and core).
Relearn: making the car accept the new sensor
A new sensor has its own ID number, and the car must learn it. There are three procedures, and your car uses one of them:
- Auto relearn — drive for 10–20 minutes above about 20 mph and the car picks up the new IDs on its own. Common on many European cars.
- Stationary relearn — a sequence of ignition and button presses puts the car into learn mode, then each sensor is triggered with a TPMS tool. Common on GM, Ford and some Asian brands.
- OBD relearn — the new IDs are written to the car's module through the diagnostic port with a TPMS tool. Common on Toyota, Lexus, Nissan, Hyundai and Kia.
Every sensor we list states which procedure the vehicle needs, so you know before ordering whether you can do it at home or will need a workshop with a tool.
How long sensors last
The battery is sealed inside the sensor and cannot be replaced. Expect 5 to 10 years or roughly 100,000 miles depending on how much the car is driven. Sensors on the same car usually fail within a year or two of each other, so if one has gone, it is sensible to budget for the set.
Choosing the right sensor: checklist
- Confirm the car has direct TPMS (pressure figures on the dash or sensors visible inside the wheel).
- Check the frequency for your car's market — 433 MHz for EU/UK-built cars, 315 MHz for most imports.
- Match the OE part number printed on the old sensor if you can get to it.
- Check whether the car needs auto, stationary or OBD relearn.
- Choose the valve type that matches your wheels (clamp-in for most alloys, snap-in for many steel and newer alloy wheels).
At AVT Expert every TPMS sensor is listed with its frequency, OE part numbers, relearn method and the exact years, makes and models it fits. If you would rather not work it out, send us your VIN or registration number and we will confirm the correct sensor before you order. Browse TPMS sensors.