I just brought a 2009 Mitsubishi Galant from a friend and if runs amazing, only issue is that my tire pressure light blinks for the first minute then remains solid lit. I made sure the tire size is correct and that the pressure is at the right level but the light still remains on and my speedometer is not reading the correct speed.
GPS app on my phone reads 45 mph when my car is reading 40 mphs. I was told it could be the TPMS that's faulty.
What can I do to fix it?
You say you bought from a friend. Did your friend ever change the TPMS sensors? Usually with blinking light the likely culprit are the sensor batteries in one or more tires is bad. The life expectancy on those is generally 5-10 years, so if they’ve never been changed and it’s 11-12 years now it’s about due. Because the battery is sealed in the unit, you’d have to replace the whole sensor. And in this case you’d want to do all 4 tires. They are not cheap. Scotty has an alternative if you are interested:
https://m.youtube.com/watch?v=0qMbPmUseoc
The speed reading does not have to do with the TPMS.
The batteries in your sensor(s) is probably bad. It costs a fortune to change them because you also need to reprogram them.
It sort of does. Some cars use the speed sensors to recognize when the tire pressure is low.
Getting the new sensors, no problem... It doesn't seem that expensive. I know a mechanic who can help me place the new ones and help me reprogram it as well. I just hope it will also fix my speedometer being off because I pretty much confirm that driving at city speed, my car reads 40mphs, I passed a construction sign that reads how fast one going and it says 45mph when I pass then... And they go nearly 10mph off when I'm at highway speed. I was told about another sensor somewhere near the transmission but not sure if that's even the reason.
It’s quite normal for most cars’ speedometers to over-read your actual speed.
by 5mph .... I dunno about that
Indeed. Usually, I see ~2mph over the GPS speed.