Q What is the best way to warm up my car after it sits overnight in my unheated garage? I respect the warnings about not letting your car warm up in a garage even with the door open. I back into the garage and typically let my 2000 Saturn SL2 idle for 60 to 90 seconds before driving out of the garage. Should I put my car in park to idle for a few more minutes in the driveway, or should I just leave it in gear and keep the RPMs down until it's up to temperature?

A I like your mechanical sensitivity to your car; that's the key to vehicular longevity. But with the concern over idling in the garage with the car backed in, let me suggest a simple compromise. Park nose-in, so that when you start the car with the garage door open, the exhaust is near the large opening. Wait perhaps 10 seconds until the engine idles down smoothly, shift into reverse and back out into the driveway. Leave the car in gear, hold it with the brake and let it idle for 15 to 30 seconds -- depending on how cold it is outside -- until you're satisfied it's ready to roll. Then release the brake, back out, shift to drive and gently drive the car up to temperature.

This procedure helps the engine and drivetrain warm up more quickly and the catalytic converter reach operating temperature faster, allowing the engine management system to shift into the more efficient "closed loop" operation with oxygen sensor feedback sooner.

With today's extremely precise fuel/spark control, there's no need for much warm-up -- it's actually better for the vehicle to drive it gently up to temperature. Obviously, there are exceptions. If it's 20 degrees below zero, warm it up a bit longer.

Q The alarm on my daughter's 2002 Honda Accord V6 malfunctions. When she locks the car, the alarm eventually goes off at some point. We wanted to simply deactivate the alarm, but the dealer was going to charge about $350 to do this. We don't need the alarm, but she wants to be able to lock her car. Isn't there any simpler way to disable the alarm system?

A Try troubleshooting the system to identify which sensor or switch is triggering the alarm. According to Honda, "the accessory security system has a cool feature that lets you know if there was a security system violation, what sensor was tripped the last time the system rearmed itself, and which sensor triggered the current violation."

If this happens, the status LED blinks twice per second and the parking lights flash three times when you unlock the door with the remote transmitter. If you press the disarm switch three times within five seconds of disarming the system, the LED blinks one to five times, pauses and repeats to identify which sensor triggered the alarm.

According to my Alldata automotive database, the alarm system has a separate horn behind the left side of the front bumper.

Q Occasionally the check-engine light on my '04 Dodge Intrepid with 90,000 miles will light up from an oxygen sensor code. The light goes off after a few days and stays off for weeks or months at a time. This seems to happen when the road is wet or after washing the car. Would I need to have the whole catalytic converter system and both sensors replaced?

A If the code is triggered by one of the front O2 sensors, replacing it is a simple fix -- and you might notice a slight improvement in performance and fuel economy. If the code indicates a downstream sensor that monitors catalytic converter efficiency, well, that's another story.

Identify the specific fault code and check the connection for that sensor. A scan tool can also monitor sensor performance in real time to help pinpoint the problem.