This is about the tire pressure monitoring system. When it gets about 20 degrees F or colder, the indicator states low tire pressure. Checking the tire pressure reveals all pressures are equal and normal. When the weather warms up, the indicator turns itself off.

- Wheelersburg, OH, USA

My car comes with a TPMS system to monitor the air pressure in each tire. Intermittently the warning light indicating there is a problem with one of the tires comes on. A check with a pressure gauge of each tire always indicates a false alarm. Talking with other Sonata owners I have anecdotal evidence that I'm not the only one with this problem. When bringing the car back to the dealer they say they can't fix it because there's no issue when the car is at their garage. This can be a dangerous problem for a number of reasons - 1. the false alarm is distracting, at highway speeds this can cause the operator to think they should pull over in a dangerous environment to avoid having a bigger problem. 2. after it happens a couple of times the operator might ignore a real problem. Yet the manufacturer refuses to address the problem.

- Newtown, PA, USA

The valve stems on a 2011 Hyundai Sonata with only 20,000 miles on it were so corroded and seized in place that in order to remove them we would have had to break the entire valve stem. Since the valve stem is attached to the tire pressure monitor we would have had to replace the whole tire pressure monitor.

- Spanish Fork, UT, USA

Tpm system malfunction: The tire pressure monitor warning light started flashing and turned solid. Immediately stopped and checked the pressure in all 4 tires. All tire pressures were within the normal range. After a few miles the warning light reset. 6 hours later the same malfunction occurred. Again, checked tire pressures and everything was normal. This has been an ongoing problem. I have communicated all occurrences to the manufacturer with no resolution of the problem.

- Chocowinity, NC, USA

TPMS: TPMS light goes on, although tires are correctly inflated to 35 psi. 4000 miles on the new ca, 18" wheels and hankook optimo H431 tires installed as original equipment. Car purchased in portland Oregon (town 'N country) and driven back to albuquerque, nm about 8/6/11. Ran 12 weeks without incident, but then TPMS light intermittently came on. Sometimes in regular weather, sometimes in cold, and would remain on throughout drive. Turned car off, then restarted, condition persisted. Other days, not at all. Checked psi and was at factory spec. Took vehicle to local dealer (southwest Hyundai, abq, nm) which checked the psi and confirmed properly inflated. Tested/cleaned TPMS but condition not rectified. Then dealer overinflated tires, claiming that altitude and temperature affected tires and tire pressure. Claimed that over inflation rectified condition. Told that this was a frequent problem in albuquerque, that regional office had been contacted on other occasions, but never received an answer or bulletin how to handle the problem. Protested, since both car and tire mfgrs specify 35 psi, and TPMS light did not go on for first 12 weeks driving at this altitude; that over inflation affected tire contact with road, tire life, and comfort of ride. Called hankook tire mfgr who said that neither temperature nor altitude could explain problem. Said likely defect in TPMS system. Called customer service and was initially told that condition had been fixed per dealer. After repeated calls, customer service had no answer and referred me back to dealer. Spoke with dealer again and service rep again claimed that condition is due to altitude and/or temperature. Message pending for [xxx], service dept. Manager. Information redacted pursuant to the Freedom Of Information Act (FOIA), 5 U.S.C. 552(B)(6).

- Albuquerque, NM, USA

Defective tire pressure monitor system. During a 5 month cycle with a distance driven of 4500 miles, the tire pressure monitor system warning light was activated 7 separate times during normal driving conditions. Checks with a pressure gauge immediately following activation showed that the tire pressure was within 1 psi of the recommended tire pressure. On each occasion the tire pressure monitor warning light reset without any manual intervention. It would take from 20 miles of driving up to 200 miles of driving to reset. The service department had inspected the system following the initial activation and suspected radio frequency interference as being the cause.

- Chocowinity, NC, USA

Vibration in steering, grinding noise in transaxe, low tire pressure (by dealer), refusal to perform 3,750 mile maintince secdule (dealer refused).

- Mcadoo, PA, USA