A few months ago my TPMS warning light activated on a couple of occasions, there were no foreign bodies in the tyres and all of the pressures were correct. My local Mazda dealership reset the system and all has been ok until yesterday.
During a 150 mile round trip and on my return journey the TPMS warning light came on, I stopped the car and carried out a visual check. Everything looked ok so I carried on with my journey.
Early this morning with the car standing in the garage overnight I checked the tyre pressures - all four correct at 29psi, and no foreign bodies in the tyres. I can only assume the extreme temperatures at present may have affected the TPMS system. Rightly or wrongly I pressed the TPMS Button to cancel the warning light.
My Suzuki Swift Sport also has a TPMS system but of a different design with what I believe are special valves fitted to the wheels. This system has never once activated during 2 years and 16,000 miles.
The Mazda system uses the ABS sensors to detect wheel speed variation. A deflating tyre runs at a smaller diameter and so rotates faster. It is likely just a spurious reading, depending on how the computers is set to check. Certainly if it is taking readings while you are at a point when you are manoeuvring the car or going round a long bend the outside wheels will be rotating faster than the inside. It is usually a combination of circumstances, even things like the tyres on the sunny side of the car will pick up far more heat and make a pressure variance, that can trip that threshold. If the tyres are OK, then I wouldn’t get stressed. You will be far more unhappy if one of the sensors goes down on the Suzuki.
This is just a thought, and I admit I have no experience of this system on a Mazda (only on my wife’s VW Scirocco), but maybe the Mazda system is a little too sensitive, as opposed to being inherently weak or temperamental !
I suppose only the main dealer can shed any light on the matter.
From the service manual… (my TPMS lit after driving over some temporary motorway lane separators -presumably from the resonant frequency detection).
Detection of the tire air pressure is performed by combining the following two methods. Dynamic loaded radius detection
Detects the tire rotation speed using the ABS wheel speed sensor. The rotation speed of each of the wheels is compared to detect decreases in air pressure. Normally, the rotation speed of the 4 wheels is nearly the same, however, if a decrease in air pressure occurs in one tire, the dynamic loaded radius of the tire becomes smaller, the rotation speed of that tire increases, and a difference in rotation speed occurs. This method of detection is dynamic loaded radius detection. With the dynamic loaded radius detection method, if the tire pressure of all 4 tires decreases at the same level, a difference in tire rotation speed for each wheel does not occur and, therefore, detection is not possible.
Torsion resonant frequency detection
With torsion resonant frequency detection, detection of differences in tire air pressure is possible even if the tire pressure of all 4 tires decreases at the same level. This detection method uses the ABS wheel speed sensor signal the same as the dynamic loaded radius detection method. With resonant frequency detection, the signal from the ABS wheel speed sensor is analyzed in single pulse units and various wave frequencies are detected. Among these wave frequencies, the wave frequency synchronized to the air pressure is the torsion resonant frequency. Therefore, by monitoring the torsion resonant frequency, decreases in air pressure can be detected indirectly.
The second method is very effective at detecting if the tyre is slightly out-of-round, long before you begin to notice the vibration, and sometimes even might be triggered by a rough wheel bearing. It might also detect if a balance weight is missing, as was the case on a friend’s C220.
As I understand things, tyre pressure warning systems were first introduced in conjunction with “run-flat” tyres. The reason for this is that run-flats don’t look appreciably different whether there is pressure in them or not. However, they do need the correct pressure in them to work properly and they have a maximum speed/distance when punctured, just like a space saver tyre does.
Without run-flat tyres, it is more visually obvious that the tyre is down on pressure and although I believe TPWS is now required on all new cars, they can be a bit of a nuisance by giving spurious warnings.
My BMW 330D had run-flats on it when I bought it (second hand) and the TPWS activated when I was driving it home from the dealer. The pressure of one tyre was very slightly down, which I rectified within a couple of miles, at the first service station I got to.
I later discovered that “run-flat” tyres were fitted to those BMW cars because there is a wheel size difference between the two axles, which would otherwise require two different space savers to be carried. Unfortunately, when I did later get a puncture in a rear tyre, I discovered that all the “run-flat” tyre allowed was for the car to be driven to a tyre dealer who told me I had to wait ten working days for a new run-flat of the correct type to be delivered. A total backward step, seeing as the car is my daily driver! It now has non-run flats on it, far easier to source. I now carry a heavy duty puncture repair kit and a tyre inflator/latex injection kit to get me to a place where I can buy a replacement tyre.
The trouble with having the system trigger the warning light, for what turns out to be no reason, is that the driver loses all faith in the system.
The system is obviously there to warn of impending danger - a slowly deflating tyre, at speed on the motorway for example. If the driver gets so blase’ about the warning light coming on, and ignores it, one day he might be doing 70 mph (or more !) on a motorway and something dangerous might occur - all because the system became so unreliable, that he didn’t take any notice of it anymore.
I had a strange experience recently with my ND. On holiday, we were staying in a cottage situated up a mile-long, very rough farm track. Each morning as we made our way down to the road the lane departure and stability control lights would come on. At the end of the lane I’d turn the ignition off and on again and the lights would go out. I blamed it on the roughness of the track messing with some sensor or another …
I’m having frequent (a few times a few times a week, sometimes more) false alarms being generated by the TPMS (2017 ND1)
Reading the post it looks like the TPMS is entirely electronic, monitoring the rotation of the wheels.
Are there any sensors that could fail or may need replacing? I think I have a theory on what the problem is, but wanted to see if it was a TPMS failure.
My golf mk7 uses the abs and wheel rotation l. I was havin the tpms go off regularly and the dealer could not identify any issue.
In the end I figured it out myself. Turns out that the tyres on an axel had been changed at different times, so one was worn fairly low and one was nearly new.
The difference in the cercumfrance of the tyres aswell as them heating unevenly was enough to set of the warning.
Changing the tyres and havin them all roughly the same amount of wear has resolved it for me. Not gone off once since.
Not saying this is the same issue for you but something to consider. It’s not always the tech that’s wrong/faulty. Sometime it’s something that when you finally figure it out you wonder how you missed it in the first place. I know I did.