Q: Ever since buying it, I’ve experienced a nagging issue with my 2015 Chrysler Town & Country. Specifically, driving the vehicle at highway speeds (60 mph and above) causes the steering wheel to shimmy in a rapid and constant back-and-forth motion. It seems similar to the response you’d get applying the brake with a warped rotor, except this shimmy is constant when driving at higher speeds. The shaking stops below 60 mph. It’s all very annoying.

The van has been back to the dealer’s service department several times. They have force-balanced and weight-balanced the tires (Yokohama Avids) several times, examined the tires and rotated the tires. Nothing has cured the problem. The service manager admits the shimmy is still there but says it’s less-severe than before. I’m the one who drives the vehicle and I don’t agree with him.

What do you think (or know) about this problem and a possible fix? The dealer says there is nothing else they can do and suggests I buy four new tires. I am not a happy camper and think they’re avoiding the real problem.

A: This has to be a frustrating situation for you.

My gut feeling is that it may not be the tires due to the fact that the shake is still there after a force-balancing job and a rotation of the tires. I pulled up a couple of service bulletins issued by Chrysler related to steering wheel shake.

One bulletin, 22-001-14 rev. A, presents various diagnostic procedures to help determine if the shaking is being caused by a tire wheel assembly or possibly the powertrain.

The other bulletin, 05-005-14 rev. A, relates to a possible imbalance in the brake rotors. The front rotors are to be inspected to see if the Julian date falls within a certain range. If so, the rotors and brake pads are to be replaced.

If both of these procedures have been performed and there is still shaking in the steering wheel, I think the dealer owes you the time and trouble to try placing a different set of tires and wheels on the minivan for a thorough road test to determine if the fault is in fact in the vehicle or the tires and wheels. If the shake is still there, it’s possible there could be an imbalance in a constant velocity shaft.

Q: I keep seeing advertisements from my auto parts store that say I should replace my oxygen sensor to get the best gas mileage. Is this really necessary?

A: When oxygen sensors first appeared on cars in the late 1970s, no one was really sure how long they would last. Some had very short service intervals. Experience has shown that they can last as long as the vehicle. Your onboard diagnostics system does very comprehensive testing of the oxygen sensor on an almost daily basis and will certainly alert you if it is operating out of specifications.