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I had my 2012 GMC Terrain serviced:

  • Tire Rotation
  • Brake System Flush
  • Wheel Alignment

Before taking the vehicle in, there were no outward signs (alerts, false-positives or otherwise) of any problems with any of the tire pressure sensors. During the service, the rep from the GMC dealership called and said we are now getting a fault in tire monitoring system and they quoted me $250 to replace the sensor. After explaining to him that we didn't have a problem before we brought the vehicle it, he said that the sensor was probably going out and having the vehicle service revealed the problem.

We declined to repair the sensor due to the price, but now the dashboard throws up all kinds of persistent and annoying warnings.

So my question is, during the course of having these services performed, is it more likely that the sensor was damaged by the technician, or is the claim that we brought it in with a bad sensor, and the act of servicing the vehicle made us aware of it?

Thank you.

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2 Answers 2

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Welcome to the site. To be honest, there is no real way for us to know how to answer your question. I know the sensors do go bad occasionally. There isn't a way for the technician to damage it unless they take the tire off. So, who really knows?

My advice...go somewhere else. Tire service companies replace these regularly for a fraction of the price. I looked up the replacement sensor for your vehicle and it was only about $43 USD.

My opinion...dealerships are know for marking up prices because they sell "genuine OEM parts", then charge outrageous labor.

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  • I had a similar thing happen to me once each at two Toyota Dealership shops. I don't know what it is about the sensors that makes them so fragile. My guess - the tech was sloppy when removing the tire from the rim.
    – mike65535
    Commented May 2, 2018 at 17:42
  • @mike65535 I agree, they were probably sloppy. It's quite easy to damage a sensor if the tire tech isn't careful with the tire-changing machine. That said, it's not very difficult to keep the sensor intact, the operator just needs to ensure the arm of the changer doesn't come near the sensor when removing or replacing a tire. If they're not careful, though, then the rotation of the machine will easily destroy a sensor during changing.
    – Shamtam
    Commented May 2, 2018 at 17:45
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It's possible the car maps tire sensors to a specific location (front-left, front-right...), and by rotating the tires and changing the pressures accordingly, the car's computer thinks there's a problem with the tire pressures since the sensor the car is looking for won't have the right pressure. For example, if the front tires call for a higher pressure than the rears, and after rotation, the tires that were on front are deflated, it's possible that the TPMS will think they are underinflated. If this is the case, the TPMS system in the car will need to be re-programmed accordingly. For some cars, there is a procedure to reset that doesn't involve a dealer or a shop. For other cars, it will require a special tool. Re-programming these cars is a trivial task for the dealer and most tire shops, or if you have a suitable tool (generally will run $100USD or more).

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  • That vehicle - and every other one I've seen that has TPMS - has a pretty simple procedure for telling the computer which sensor is on which corner, without a Tech II or any other special tools. And, the computer can't tell, without some nifty triangulation system that it doesn't have, which wheel is where. It'll just report the wrong pressure on "left front" when that tire is actually on "right rear." This answer is completely wrong.
    – 3Dave
    Commented May 2, 2018 at 21:06
  • @DavidLively Well my Subaru (plus most Toyotas, just to name a couple) have no way to re-program the TPMS without something like an ATEQ Quickset or manufacturer-specific tool. There are plenty of threads on the web that show this exact problem after a tire rotation, where the car's computer triggers a low-pressure warning after rotating tires without resetting the TPMS. It seems most of them self re-learn after several miles of driving, though, so it's nothing more than a temporary issue.
    – Shamtam
    Commented May 3, 2018 at 0:54
  • @DavidLively I'll concede the "triangulation" point, since I was under the impression that many cars use multiple receive antennas (one per wheel well) instead of a single antenna. I'll edit that part out.
    – Shamtam
    Commented May 3, 2018 at 0:55

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