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I had my oil changed at the dealership on Friday. They did not rotate the tires. On Monday morning, after I started the engine, I noticed the TPMS light is on. According to the owner's manual, it isn't supposed to come on until you go over 20 MPH. I checked the tire pressure, and it's low in all 4 tires. According to the door jam label, the front tires are supposed to be 33 psi, but my left front tire is 23 psi. The other three tires are all approximately 25. You'd think the dealership would check the tire pressure when they did oil change. Odd that all 4 tires would lose pressure 3 days after an oil change.
 

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I went to the Dealership yesterday and they put air in all of tires (35 psi) and the light went off. I think you're right tdelker, i.e., I think when they checked the air during the oil change they actually let out a lot of air.
 

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I realize this is an old thread. However, as FYI on this topic, many shops/mechanics use the standard "stick" tire-pressure gauges. In my experience, 75-95% read ~2-10 psi higher than actual pressure, right out of the package - brand new. The result is that when they set tire pressure to the "comfy" pressure that most OEM's list on the car-door frames (already much lower than the pressure range recommended by the tire OEM for even contact-pad pressure across the tread), the result is low to horrendously-low tire pressure. Tire shops seem to do this too, as standard, because the result is that the shoulders wear the tread down faster: while they can use the tire tread depth gauge on that area to show that you should replace the tires, the more weather-critical center area of the tread still has plenty of water-channeling capacity for typical hydroplaning concerns.
For those reasons, I trust only the round bourdon tube mechanical gauges, or a digital gauge that has a published guaranteed accuracy on the package. (Half or more of them in auto-parts stores list the accuracy.)
 
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