Q: I have a 2001 VW Golf TDI. It starts right up but after I drive a few feet, the "Check engine" light pops on. I get a code P0380. I replaced the glow plugs, as they had 120,000 miles on them. Any help would really be appreciated.

A: According to my ALLDATA database, the P0380 DTC fault code relates to a problem with the glow plugs, the glow plug relay or the RPM sensor. But first, a question: Did you have the P0380 code cleared from the engine control module (ECM) after replacing the glow plugs? A scan tool is required to clear DTCs; they cannot be cleared manually.

If the P0380 code has returned after having been cleared, there is a continuing issue. The glow plugs on this diesel engine are controlled by the ECM, which engages the glow plug relay to turn them on to "preglow" to warm the air in the combustion chamber adequately to start the engine. When the glow plug light goes off, "preglow" is finished and the engine is ready to start. After the engine starts, the glow plugs operate in "afterglow" mode to shorten warmup time, reduce combustion noise and emissions. The "afterglow" mode lasts until engine RPM reaches 2,500, coolant temperature reaches 140 degrees F. or three minutes elapse.

Since the "Check engine" light comes on after the vehicle is in motion, meaning that engine RPM is likely above 2,500, the problem may well be associated with the RPM sensor.

Q: My vehicle is kept outside all year. I did not get a good coat of wax on it before the cold and snow arrived. How do I get the snow and road grime off during the cold weather without having the doors freeze shut?

A: Whether or not the vehicle has been waxed, the only way to remove road debris, dirt, grime and — worst of all — salt is to wash the vehicle regularly and thoroughly. It's best not to wash a vehicle when temperatures are seriously below freezing, but if temperatures are or will be in the 20s or higher, wash the vehicle. In addition to the exterior painted surfaces, it is critically important to flush the underside, wheel wells, bumpers, valances and any areas that can trap winter debris. Also, wash the inside edges of the doors, hood and trunk along with their jambs and sills.

How can you keep the doors, hood and trunk from freezing closed after washing? Dry the inside edges, seals/gaskets, jambs and sills, then apply aerosol silicone spray to the door seals and gaskets and their contact surfaces.

To finish up, insert the extension tube of a spray lubricant/moisture dispersant like Deep Creep into the outside key slots and spray liberally. Do the same to the locking mechanism on the door jamb. Then operate each lock/latch a few times to make sure the lubricant is well distributed.

Q: We bought a 2002 Lexus RX300 with 134,000 miles on it. The "Check engine" light indicated an issue with the camshaft sensor. The owner of the dealership said that if the vehicle was his, he wouldn't spend the money to replace it. What do you think?

A: A scan tool can identify the specific fault code associated with the "Check engine" light. P0340 indicates a cam sensor issue. P0345 indicates an issue with the variable valve timing actuator position sensor. Both are easily accessible under the engine cover. The cam sensor costs roughly $85 and takes about 20 minutes to install. Since both of these are part of the variable valve timing system, if either is faulty I wouldn't hesitate to replace it.

The dealer may be thinking of a more expensive failure of the variable valve timing system, but until you know the specific DTC that triggered the check engine light, you won't know.