BMW E90 tyre pressure monitoring (RDC)
How do you initialise the E90 tyre pressure monitoring?
Always initialise the monitoring after correcting tyre pressures or changing tyres. Start the car but do not drive. Select tyre pressure monitoring in the on-board computer menu and confirm with the BC button. Hold the button for about 5 seconds until a symbol appears on the display. If no symbol appears, there is a fault in the system.
Why does the tyre pressure warning come on when it is cold, even though the pressures are fine?
Cold lowers tyre pressure, and the warning often comes when the car moves from a warm garage into freezing weather. Check the pressures and initialise the system again. Pressure changes by about 0.1 bar for a ten-degree change in temperature, so in winter the pressure should be checked cold.
When is the tyre pressure sensor faulty?
If the warning comes on repeatedly at a cold start and there is nothing wrong with the pressures, the valve sensor may be faulty. The sensor is replaced (part number 36 14 6 792 829) or the active monitoring is coded out, in which case the system monitors wheel rotation speed. The coding requires a specialist workshop. A leaking valve can also cause the warning.