Q: I have an issue with my car warming up slowly when the temperature gets down around 0 degrees F. The car is a 2011 S40 Volvo with the T5 engine. The dealer confirmed that the issue I describe is happening but say they checked another 2011 S40 they had on the lot and it did the same thing. I find it strange that it takes 20-minutes-plus on the highway to reach operating temperature and that if you stop and run the heater at full output the engine temperature drops.

A: You didn't mention how long you've owned the vehicle and whether this is the first winter in which you've experienced this problem. Regardless, I'm surprised the dealer didn't at least check the thermostat for proper function. Like most liquid-cooled engines, your vehicle utilizes a thermostat to restrict coolant flow until coolant temperature reaches 194 degrees F., then maintains coolant temperature in the 194-221 range.

If the thermostat fails to close properly when the engine is cold or sticks in a partially or fully open position, symptoms will be precisely what you've described — long warmup times and the inability to maintain operating temperature, particularly in cold weather.

Why not apply the KISS principle and try the simple stuff first — replace the thermostat and make sure the coolant level is full. Keep in mind that if the coolant temperature gauge reads significantly below normal but you're still getting hot air from the heater system, the issue may be a faulty coolant temperature sensor mounted on the thermostat housing.

Q: I like to back my 2009 Silverado Hybrid 6.0 Liter V8 into my driveway. That way I don't have to back out, which is considerably safer. I currently have a large snowbank at the end of my driveway. On two occasions I have backed my truck into the snowbank. The tailpipe ended up ended up obstructed with snow and ice. When I started the truck the next day, the engine idled very roughly — almost violently — and the "Low Engine Power" alarm appeared on the dashboard. The snow and ice melted from the tailpipe fairly quickly and the engine eventually regained power and operated normally. Ultimately the "Service Engine Soon" alarm cleared on its own. It has been over a week since the second occurrence and I have noticed no ill effects after the engine started operating normally again. Is there any possibility of undetected damage?

A: I don't think so. The warning lights, alarm and driveability issues were directly related to the restricted exhaust. A failed catalytic converter or physically damaged exhaust pipe could cause the same thing. Potential damage, although very unlikely in this case, could include engine overheating, catalytic converter failure, pre-ignition/detonation or burned exhaust valves.

In the "Low Power" mode of operation the engine management system operates in a self-protective mode to prevent any damage — which "saved the day" in this case.

Q: What is the current thinking on the value of daytime running lights (DRL) as a safety feature? Some states have legislated their use. Our 2006 Buick Lucerne has them but our new Chrysler minivan does not.

A: The idea behind DRLs is to increase visibility of your vehicle to other vehicles around you. There is no federal mandate but some carmakers install DRLs as standard equipment. Because they need to be visible in daylight, there have been complaints that some DRLs are too bright but with the increased use of HID and LED systems I believe this issue will fade.