idbh

I just filled my tires on my equinox to 34 psi each. Checked the pressure at each stem with a manual and digital gauge.

Went in the car and the tpms reads 40 psi for each tire. Reset the tpms and still 40 psi.

What do you trust? The pressure at the stem or the tpms?

I had this same thing happen in a 2016 chevy cruze.

tech2

did you drive the vehicle so the pressures update? the pressure at the valve stem can't be wrong as long as the guage you are using is accurate.

idbh

I started the vehicle but didn't drive it. I will give that a try right now. Just seems strange that 2 gauges read 34 psi, but the tpms shows 40.

I will update if driving fixes it.

Thanks for the reply.

idbh

No dice.

I reset the tpms in park with the car on. Let it learn, then drove. The pressure on 2 tires dropped to 39 psi, but went back up to 40. I think I'm going to have to get one of those auto fillers for the compressor. I just don't know how 2 gauges could be wrong?

repairman54

TPMS is not precise like a tire gauge. It's there to warn you of a impending flat tire so you can address it before tire failure and loss of vehicle control. Most trigger a warning at 26 psi. . All the TPMS in my fleet are always off a few pounds on my fleet.

idbh

Ok, that makes sense. Thanks for replying.

Gumby22

How did you “let it learn”? Nothing changes if you put it in learn mode and don’t activate the sensors. This can be done by using an activation tool, strong magnet (such as a magnet off a speaker), or dropping the tire pressures to about 10 PSI and then pumping them back up. The last method may not work for you - the early versions of TPMS allowed for it, but I can’t say for sure it will still work on anything built in the last few years.

Additionally, you have to follow this sequence to activate each sensor and complete a re-learn:

Driver front
Passenger front
Passenger rear
Driver rear

You will know when each sensor has been learned correctly because the horn will beep when it’s done, then you move on to the next. The re-learn is complete when the horn beeps twice.

There is also a time limit. Once learn more is enabled, you have 2 minutes to complete it. After that, it times out and you have to start over again from the driver front tire. It’s best to make sure the sensors are “awake” before attempting a re-learn by driving above 25 MPH for 2-3 minutes.

If the readings on your info center differ more than 4 PSI (above or below) from your gauge, there is an issue with the sensors or with the module. If it is the sensors, sometimes a successful re-learn will correct the issue but there’s no guarantees.

Not true. The same type of circuitry that’s used in a digital tire pressure gauge is what’s used in a tire sensor. Each manufacturer may have slightly different designs and components, but there’s no reason a sensor that’s working correctly should differ more than 1-2 PSI from a handheld gauge, digital or mechanical.

As for when the sensors trigger a warning, it depends on the manufacturer’s chosen calibration (programmed into the module). I’ve seen some that go off with as little as 2 PSI difference. Dodge/Chrysler sensors (on their vans at least) are calibrated for 36-40 PSI - if the pressure is outside this range (could be one tire or all of them), the warning light comes on. GM’s service manual states a difference of 1.2 PSI will trigger a warning light.

idbh

The method I used was to start the car, reset the tpms in park, (it honked twice) let it finish relearning, then drive.

If I put the car in drive after resetting the tpms it turned off the learning notification.

Not sure what to do. I bought an auto fill gauge for my compressor. I set it to 34psi and filled the tires. 2 gauges show 34psi. The tpms reads 41psi. I am trusting the gauges till I can figure out the correct procedure. It shouldn't be this difficult, oh well.

Gumby22

As stated previously, if all you’re doing is turning on learn mode and letting it sit - engine on or off - then it’s not doing anything. Even though the info center is telling you “Relearn Complete” (or similar phrase) it’s only doing what it’s programmed to do. What’s actually happening is that the learn mode is timing out - it only stays in learn mode for 2 minutes, then no matter if all the sensors have been learned or not, it’s done.

The sensors have to be individually activated so the car knows which sensor is in which position. If you’re having difficulty figuring it out, go to a shop.

tech2

I have no idea what idea what you are talking about...do you?