Hi,

I got new tires and the tpms light came on after 150 miles.
I filled them to 40psi (same as the old tires were for years)
And it's been another 150miles, the light is still on
Pressure is good unless two different guages which agree are both wrong.

No codes either. It's the low pressure light, not the Tpms malfunction light.

What should I try next?
Got the tires at Walmart and even with an appt it was a 2 hour affair. Really. Really want to avoid going back even if it is their fault.

 

What year Fit?

If it's the newer model, did you remember to push the reset button when the car was cold?

Either way, isn't 40 psi quite a bit more air than recommended?

 

Its a first gen, 2008, no reset button.

Tires good for 51, I honestly don't know the factory recommended pressure. But I had them at 40 before without issue.

Im thinking those idiots at Walmart broke something
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Factory-recommended pressure should be on a sticker on the driver's door frame and in the owner's manual. The maximum pressure listed on the side of the tire is NOT the recommended or maximum pressure for the particular car using those tires.

I don't know about your car but the next two generation Fits have pressure in the low thirties.

 

If one or more TPMS sensors are "unregistered", you should see the TPMS malfunction light within 50 miles of highway driving.
"Unregistered" could mean the tire store damaged and replaced one or more TPMS sensors without telling you (unlikely, because individual sensors cost $25 and up, and they'd likely charge you to replace them),
-OR-
The battery in one or more TPMS sensors has died.
After 14 years, a dead sensor battery is definitely possible.

The Honda TPMS system is designed to alert you to differences in tire pressure among the four tires.
When all tires are within 2 or 3 psi, you SHOULD NOT see a Tire Pressure (triangle) indicator light, whether they're all inflated to 30psi or 50psi.
If one tire is 5lb or more low (according to the TPMS sensor), you SHOULD see the light.
If all tires are uniformly 10psi low, but still within 2 or 3 psi, you won't see a light!

Any reputable tire shop (including Walmart) SHOULD have a tool or two tools to trigger and then scan each TPMS sensor, and update the car computer, if necessary.
They should also be able to display or print that information for you.

If it is not the place where you got the tires installed, they probably will want to charge you a fee for doing that.

Outside chance, but if Walmart switched wheel positions and did not re-trigger the TPMS sensors, that might be an issue, based upon my ownership of an *ATEQ Quickset-X* TPMS tool (US$250 retail) that I use with my son's 2013 Honda Fit Sport. The TPMS system initially registers tires and sensors in a particular order, beginning with the left front (driver side) and proceding counterclockwise around the car to the right front. The spare does not have a TPMS sensor, and is not scanned.

Last thought, if you're desperate and Walmart is a long distance away - You can trigger TPMS sensors in many cars (not sure about Honda) by lowering the tire pressure in each tire by about 15 lbs, and then re-fill them to the desired pressure.

If all sensors are working, the triangle Low Tire warning should go off within 5 or so miles of highway driving.

Hope this helps!

*ATEQ Quickset X* - We annually switch to winter tires/wheels, and back to summer tires/wheels, so two sets of wheels/tires/sensors.
The 2013 Fit stores just one set of TPMS sensors at a time.
Having a Quickset X lets me to trigger, read, and then update the the stored sensor info to the car via OBDII cable when we switch between wheel/tire sets, without going to the tire store or the dealer.

 

32psi is what the door says, front and rear.