Bagpuss12

Active Member
Feb 5, 2022
28
3
My tyres recently needed inflating however the warning sensor never sounded? It has done previously throughout my time owning the car? Could this be a fuse issue or one or more failed sensors? When I calibrate and reset the pressures it accepts it and flags up no issues?
 
It's not that accurate, ive seen a loss of 8psi when the warning comes up. That's a lot of pressure to lose, you would think it would go off before then.

Works via the ABS system on these.
 
My tyres recently needed inflating however the warning sensor never sounded? It has done previously throughout my time owning the car? Could this be a fuse issue or one or more failed sensors? When I calibrate and reset the pressures it accepts it and flags up no issues?
I don't think the warning will flag up if the tyres lose pressure evenly, so if the normal pressure is say 32psi when set, if they drop to 25psi over time the tyre pressure warning won't work.
 
When I calibrate and reset the pressures it accepts it and flags up no issues?

If you or any previous owner didn't retrofit a TPMS which employs a separate control unit and a dedicated sensor in each wheel, your tyre pressure warnings are based on data from ABS wheel speed sensors. This simpler system can not flag an issue when you reset it. There's nothing like a "calibration" at that moment and the reset only marks the start of a learning procedure, where the system saves the speed information from each wheel when you start moving the car, and later compares that stored data to actual speed and calculate the possible deviations from it. Leon Mk3 was never offered with that more sophisticated system, so those who retrofit it on their Leons were actually using parts that were meant to be used in Golfs, Passats etc.
 
Just to add on the MK3 with stock system you can only re-calibrate with the car stationary.

With regards to the change in behavior have you run a diagnostic scan to see if any errors are being reported but my personal experience is that when there are issues with the speed warning sensors then you have xmas lights on the dash as the ABS Unit is linked to lots of other functions.