TPMS light.

[rallytaff]

Checked all 4 tyres. 39 front, 36 rear. Light on dash didn't go out after trip. Any ideas?

 

[Capri to ST]

Maybe one of the sensors is bad?

 

[rallytaff]

Unfortunately, our cars don't tell you which one. I'll go to the dealer tomorrow and get one of the mechanics to look at it. If the tyres are still keeping the correct pressure, I can ignore it for now.

 

[SteveS]

If you have one of the cheap TPMS sensor training devices (roughly $10 on Amazon) you can use it to determine which wheel has a bad sensor. Then you can buy a replacement sensor (set of 4 for $25 or genuine Motorcraft 1 for $36) and just have a tire shop swap it. They should charge you the same as a flat repair. All they have to do is break the bead, unscrew the sensor from the back of the valve stem and screw the new one on, then reinflate the tire.

 

[Intuit]

The sensors have batteries so have a finite life span. Might make sense to just go ahead and do all of them.
Had a TPMS diagnostic tool that displayed temperature and battery level, in addition to temperature.

Do NOT purchase anything manufactured by Autel. They sold a butt ton of defective devices and won't support them.

 

[rallytaff]

Due to the heavy rain we had, I wasn't able to do that. It had crossed my mind, so I'll do that this morning as the rain has finally passed.

 

[madhatter]

don't order them from amazon either. i've gone through 2 complete sets before i changed the vendor and now they're fine. Something about the ones amazon are selling, even the genuine motorcraft ones, are bad. maybe they sit on the shelf for so long the batteries go bad, or something else, not sure. 2 sets is not a coincidence IMO. 8 tire sensors, all had to be swapped out within 6 months.

 

[Intuit]

They go dormant after awhile. I rotate between sets seasonally. It can be sdubidly hard to get them to activate; especially if the tool is bad or needs a battery. If you have one that won't activate, drive on it for a few days then try again. Still won't activate, try a different tool. Try repositioning the tool to the tire sidewall if the valve stem position doesn't work. Second tool I bought that is going bad, won't work unless I break it out of its case which directly exposes the coil. Some sensors will be more sensitive than others so there may just be that one, that doesn't "like" the bad tool.

 

[Evo8]

Another thing I have to do in my Wrangler from time to time is remove the air out of the tire and reinflate and it "wakes" up one of my glitchy tpms sensors.

 

[madhatter]

ford has a similar procedure. ignition on (not started) hit the hazard button 6 times (i think its 6) and the horn should sound and the lights flash. then let air out of each corner starting at the LF going clockwise around the car until the horn sounds 1x each time. then air tires back up to reset the light. had to do this several times in the past until i broke down and bought the $12 tool from amazon.

my son calls it a "cheat code" for the car.

 

[rallytaff]

Changed the battery in the tool and still couldn't get the light to go out. Took it to my friendly Ford dealer and literally two minutes later I had the car back with NO light on the dash! It pays to be nice to your service rep!

 

[klazge]

check your spare tire if you have one because those sensors often trigger the light when they get low even if your main four are perfect also try doing a manual reset through the steering wheel menu settings while parked because it won't always clear itself just by driving if one of your batteries is dying after five or six years you might need a new sensor entirely so a cheap tpms tool can tell you which one stopped talking

 

[M-Sport fan]

^^^Are you sure that the factory spare even has a TPMS sensor in it?

 

[rallytaff]

Have never, ever checked the tyre pressure in the spare wheel of any car I've owned. Never needed to use the spare.

 

[rallytaff]

^^^Are you sure that the factory spare even has a TPMS sensor in it?

Good question.

 

[SteveS]

I don't think there is a TPMS in the spare because the TPMS relearn procedure does not include the spare.

 

[SVTBob]

I don’t think they do; I know for sure that the spare in my Raptor (full size) does not come with a TPMS senbsor.

 

[Intuit]

100% certain the factory spare will not have TPMS. We, or USDM 2016 at least, also has no access to anything TPMS related in our SYNC3 menus.

Some people replace the factory spare with the best tire from the previous set on a full size wheel. This used to be a common practice for me but IIRC don't think the Fiesta has a well large enough a the full size spare. As someone already mentioned, the relearn procedure only accommodates four sensors, not five. (you'd have to forget/neglect to do the relearn following a tire/wheel swap)

On the maintaining a spare tire, hose down the sidewalls in silicon spray then garbage bag your spare. Not being exposed to new air in the bag, it won't oxidize like it did before. Fifteen years in the trunk and it'll come out seeming like new, come time to actually use it. Prudent to occasionally test your air pump; as well as top-off your spare. That last part minimizes time spent as a vulnerable target on the side of the road.

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