Q: My 2002 Saturn SC2 with 61,000 miles keeps turning on the "Service engine soon" light even though I've had it checked several times. At present, the light is on constantly. The technician said this probably indicates a tiny leak of gasoline vapor and is not destructive to the car. What do you think should be done?

A: Fix it. A simple scan of the PCM — powertrain control module — should identify the specific DTC fault code that is triggering the light. A number of auto parts stores will provide this service at no charge.

Since 1996 carmakers have been required to monitor the EVAP — evaporative emissions control system — for any leaks and for whether the purge and vent solenoids are opening and closing properly.

One of the most common causes for an EVAP fault code is a gas cap that does not seal properly.

Q: My question is regarding the daytime running lights becoming so popular on new cars. Why do the car manufacturers have the turn signal cancel out the DRL during the day? I see it frequently when a car is approaching with DRL lights on. The car activates the right turn signal and the right headlight goes out. Why is it programmed this way?

A: Interesting question. Daytime running lights were developed to improve visibility of vehicles to nearby motorists and pedestrians. With the increased intensity of modern headlights, the relatively low-intensity turn signal lamps on the front of vehicles can be obscured by very bright HID — high-intensity discharge — headlights. In order to make sure the turn signal on the front of the car is visible, several carmakers program their vehicle's lighting system to cancel the DRL on that side when the turn signal is engaged.

Remember the old adage "Solve one problem, create another"? Seems like DRLs, designed to make vehicles more visible to others, may be preventing others from seeing turn signals.

Q: My wife purchased a new 2015 Volvo XC60 in 2014. It now has 25,000 miles on the odometer. I noticed the rear end was grinding whenever a right or left turn was made after a complete stop. It seemed more pronounced during right turns. The dealer could not duplicate the condition and suggested that whatever I was hearing/feeling was likely due to all four tires being "cupped." The service manager told me not to worry since we had another year and about 2,000 miles of warranty remaining. Now it seems to be getting worse in that the grinding seems to be present even if not starting out from a stop when making turns to the left and right.

A: Grinding noises while turning are often a symptom of a hub/wheel bearing issue. When turning, the ball bearing tends to "lean" against the side of the bearing race. Wear or corrosion on this surface of the race is what creates the roughness or noise. Sometimes you can actually feel this roughness when, with the suspension on a jack stand, you place your hand on the coil spring above the tire and spin the wheel by hand.

My ALLDATA automotive database pulled up Volvo bulletin TJ25167 that lists a replacement hub incorporating a new splash shield to improve bearing life. Next time you take the car to the dealer, suggest that a technician drive/ride with you to experience the noise.

Motoring note: Responding to the question about the intermittent dash warning lights and gauge failures on a PT Cruiser, John Miller reported, "I had a similar problem with my 2004 PT Cruiser instrument panel. I started the engine and the panel went completely dead; no speedometer, no gas gauge, etc. The car was driveable. I removed the panel and there are two connectors that use aluminum contacts. These contacts oxidized, causing the problem. I cleaned them very carefully and used some dielectric grease to prevent further oxidation, and this has solved the problem."

Paul Brand is the author of "How to Repair Your Car" and "How to Repair Your Truck and SUV," published by Motorbooks.