Fix-a-flat a remedy in a pinch

| Saturday, Aug. 2, 2014, 12:01 a.m.

Question: Last week, I had a flat tire on my 2013 Buick Encore with only 4,500 miles on it. I got my can of tire inflator out, and when I read the directions, it said it could not be used on tires with pressure sensors in them. Is it because it would ruin the transmitter or because the sealant could not get into the tire? Could you use it in a real emergency? When I took the car to the dealer after putting on the spare, they said it was repairable and fixed it. I was told I was lucky because on all-wheel-drive vehicles, you have to change all the tires at the same time. I have never heard of this before — can you explain?

Answer: The primary ingredients in most emergency tire inflator “fix-a-flat” aerosol products are a liquefied propellant such as nonflammable HFC-134a — the refrigerant used in air conditioning systems — and a latex polymer to seal the inside of the tire.

Some earlier products used flammable propellants, which caused a danger for the service personnel repairing the tires.

The reason these products are not recommended for use in tires fitted with tire pressure sensors (TPS) is that the latex sealer may coat and interfere with the signal transmitted from the TPS, although this potential issue is hotly debated. What is absolutely true is that the latex sealer will have to be thoroughly cleaned from the inside of the tire, wheel and TPS. There is a potential issue with corrosion and delamination of chrome from the inside surfaces of a chrome alloy wheel, too.

Regardless, it is important to remember that these products are, at best, a temporary fix. The tire must be cleaned and repaired as soon as possible.

Should you use an aerosol tire inflator in an emergency, such as when stopped in a dangerous scenario or situation in which taking the time to mount the spare tire would add to the risk? I would. If the fix-a-flat product will inflate and maintain enough tire pressure to allow me to drive to a safe location, I would certainly use it.

But I'd make absolutely sure to tell the service agency that you used a tire inflator and have the tire repaired or replaced as soon as possible.

The reason for suggesting that all four tires be replaced is that all-wheel-drive vehicles must have four tires with the same rolling circumference or damage to the drivetrain can occur. As long as the replacement tire is virtually the same rolling circumference as the other three, there is no problem.

Q: I have a '96 Chrysler Concorde with 94,000 miles. The needle on the gas gauge at times is normal, but at other times the warning light goes on and it fluctuates. Is this a big repair?

A: The position of the needle on the gas gauge of your vehicle is controlled by the body control module (BCM). The BCM receives a signal from the variable resistor in the sending unit in the fuel tank, compares this with the fuel tank ground and moves the needle to the correct position on the gauge.

The intermittent issue with your gauge may well be the variable resistor/sending unit in the fuel tank, which is a significant repair, or maybe just a poor ground for the variable resistor, which is located in the left kick panel.

With the age of the vehicle, I'd first check the ground connection.

Paul Brand, author of “How to Repair Your Car,” is an automotive troubleshooter, driving instructor and former race-car driver. Write to him at Star Tribune, 425 Portland Ave. S., Minneapolis, MN 55488; or via email at

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