Hi, all,

The vehicle in question here is a 2013 Ford Fiesta SE, but I think this issue is a better fit for this section than the Fiesta section.

For years, I've had 2 sets of tires that I've changed over seasonally, using a single set of wheels/rims (TPMS sensors installed). I finally took the plunge and bought a second set of wheels, along with a new set of pre-programmed TPMS sensors, so that I can do my own seasonal tire swaps in the future and stop paying someone to do it.

Prior to taking in the new wheels/sensors to have the tires mounted on them, I did a test to make sure the sensors were working: I placed the 4 sensors on the ground outside the car near each wheel, I put the car into TPMS re-learning mode (brake down & up, then ignition on-off-on-off-on 2x), and then I walked around the car with my Ford TPMS re-learn tool activating the new sensors in order. The horn honked after each activation, so it seemed that everything was perfect.

I took the tires, wheels, and sensors in to have everything mounted and get the tires with the new wheels and sensors put on my car. Afterward, I took the car home, parked it, and put it into re-learning mode. But now I can't activate the sensors! None of the 4 sensors are being activated by the TPMS re-learn tool. Eventually, re-learning mode times out (horn honks twice). I've tried holding the tool right up to the sidewall, against the valve, 180* across from the valve - nothing works! It's almost as if the tires are too thick for the radio signals to get through. (Not that that makes any sense.)

Does anyone know what's going on here? Does anyone know what I can do to pair the sensors?

 

Most likely when you put the sensors on the floor near the wheels you picked up the sensors already on the vehicle, last I checked Ford TPMS does not activate until there is air pressure aka installed on a tire, otherwise the little button cell batteries would be running the entire time after they leave the factory and sit on a shelf in the parts depot for a few years.
I am not sure what you mean by preprogrammed, I assume you mean they were used.
What brand are the new sensors?
You can roll one of the old wheels with known good sensors over to the vehicle and make sure it trains, if it does and the new sensors you have do not then they are bad/incorrect and you'll need another set of new sensors.

 

Good thought about picking up the old sensors. However, I actually tested for this when I was testing the new sensors (by varying distances between the re-learn tool, old sensors, and new sensors - enough experimentation to be sure that the new sensors were detected). Despite being at 0 PSI, they were detected.

I bought these off-brand sensors: They were new. By "pre-programmed", I meant they were designed to work with Fords.

Any other thoughts?

 

You could buy a high end scan tool and see what BCM fault codes you have(sensors report to BCM).
But honestly its a pretty simple system, the fault is either the sensors or BCM, only seen two with a bad BCM for this issue.
Train your first set of wheels and make sure they still train to the vehicle, if they do then you know its something with the sensors.
Ive heard good things about Autel sensors for aftermarket chooses.