2016 Civic EX - TPMS Calibration Never Verified

alternator

I added air to all four tires. I initiated TPMS calibration and got message on screen that calibration had started. Verification that calibration had finished never came and the little yellow icon remained lit.

Next time I started the car the icon was gone, but I have no way of knowing whether calibration occurred or not.

Can someone explain this ?

thecardoc3

The systems are designed to detect when a tire is 25% lower or higher, however it's going to be dependent on how much pressure was in the tires when the calibration routine was performed. By the book, you are correct at 24psi the light should come on, but what if the calibration was reset when all four tires were at 29psi? What happens if one or more tires are inflated differently than the others when the calibration is performed?

The best question is the tire pressure specification is 32psi "cold". What exactly is cold?

To correctly set tire pressures you actually have to first know what the average cold temperature is for that time of year and location. Then you have to measure the tire temperatures in Fahrenheit. Then for every ten degrees the tire measures hotter or colder than "cold" you have to adjust the present inflation setting by 1 psi. For example let's use "cold" as 60f. The specification is 32 psi. The tire temperatures measure LF 110f, RF 100f, LR 80f, and the RR 70f. To correctly inflate the tires and have them all at 32psi the next morning when it is 60f you would have to set them at.... LF 37psi....RF 36psi.... LR 34psi.... and the RR 33psi.

The real fun then is lets say that someone actually inflates the tires correctly and then resets the TPMS system without allowing the tires to cool evenly. The warning lamp would then potentially turn on when the tires reach the following pressures..... LF 27.7psi, RF 27psi, LR 25.5psi RR 24.75psi.

alternator

I was mislead by the majority of YouTube videos on this subject that say you just need to wait a minute or two after starting calibration and the little icon on the left side of the dashboard will go off and calibration is done.

Dead wrong. As I now understand it, after calibration has been started, the car must be driven a total of about 30 minutes at speeds of 30-60 mph before calibration is completed, at which time the little icon will disappear.

thecardoc3

You tube video mechanics wrong? (sarc... )

alternator

It seems I spoke too soon. I started the calibration, shortly thereafter I turned the engine off. The next time I started the car the icon had disappeared. I'll check with dealer on Thursday and report back.

Is sarc short for sarcastic ?

thecardoc3

Dripping with it.....

BTW, you only need to drive a few miles to start the relearn. The system will continue to learn the next time it is driven after it has been shut off. You should be fine, that's why the light went out.

alternator

Why did the light go out before I drove at all ?

thecardoc3

You started the calibration but didn't drive it? It might allow the system to relearn or else it just cancelled the relearn. Either way the system uses the ABS sensors to read wheel speeds and through a series of calculations can detect if a tire is inflated differently than the learned values for all of the tires. If you changed the pressures in all of the tires equally the system might not detect anything. The system only turns the light on when it detects that the inflation of a tire has changed more than 25% from the learned value when compared to the other tires.

alternator

So there's really no way to know whether or not the TPMS is calibrated?

thecardoc3

If it was truly not calibrated right now the light would be on. However if it was simply not recalibrated from when you adjusted the tire pressures, then the light would be out and the system is running with the previously learned values. That does mean that a change in inflation now "could" result in the system alerting of a possible inflation issue incorrectly.

The bottom line is to put your mind at ease, start the car and perform the reset command. Now drive it a few miles, at least up to about ten miles or until the light goes out. Then the next restart if the light is out and stays out you are good to go even though the system is still relearning.

alternator

In any case, I believe not having a sensor inside each tire is a good thing.

kyfdx

alternator said:

In any case, I believe not having a sensor inside each tire is a good thing.

Amen to that

alternator

I have read that indirect TPMS systems are often designed to give a warning only after the pressure is 25% below the recommended pressure. The recommended pressure for my Civic is 32 psi, so I might not get a warning until the pressure drops to 24 psi. That is an absurdly low set point.

Do any car makers specify the low pressure set point of their indirect TPMS systems?.

I'm afraid most car owners are in the dark on this subject, so this mandatory feature is really counterproductive. The majority of owners will wait to get a warning, before they ever consider adding air to their tires.

alternator

Thanks cardoc, I've learned a lot