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Q: I own a 2003 Honda Accord. In April a large amount of white smoke came out of the front of the car when I started it. It has happened three more times, coming from the rear of the car. Three times the engine was cold, once warm. The Honda dealer found nothing but told me to keep track of these instances. Nothing has leaked on the garage floor.

A: White smoke from an automobile can be caused by three things: condensing moisture, heated coolant and vaporized fuel. In your case I'd be suspicious of an external coolant leak that collects on some part of the exhaust system and is heated into smoke as the exhaust system heats up, leaving no evidence on the garage floor.

Do you smell the semi-sweet odor of antifreeze/coolant? Before you start the cold engine next time, open the hood and visually inspect for any coolant in the engine compartment. Make sure you are monitoring the coolant level in the radiator/reservoir.

If the white smoke is exclusively from the exhaust pipe, a leaking cylinder head gasket would be a suspect. In this case the coolant would end up being heated in the combustion chambers and blown out the exhaust as the engine starts.

White smoke from the exhaust on a cold morning start is normal condensation of moisture that has collected in the exhaust system overnight, and is of no concern.

White smoke from vaporized but unburned fuel — unlikely in this case — can be caused by a failed or stuck fuel injector allowing raw fuel to be carried through and vaporized in the exhaust system as it is heated.

Q: My 2011 Subaru is squeaking so loudly I'm ready to tear my hair out! It started on the driver's side just behind the driver's seat, moved to under the driver's seat near the middle, and then under the console. All three areas are squeaking! It's been on a lift and nothing that can be seen is an issue, according to the mechanic. A body shop owner with 40 years' experience found that the back of the rear seat hadn't been put in place properly and the spare tire was not tightened down securely. The noise lessened but is still a major nuisance.

A: The most common causes of body squeaks and rattles are something flexing or something loose. The entire exhaust system and its hangers should be inspected for evidence of flexing, movement or contact. Next, all engine, transmission and driveshaft mounts should be checked.

If the squeaking is rhythmical and varies with engine or road speed, the noise may be coming from the transmission or driveshaft CV joints. Subaru issued a service bulletin addressing a high-pitched sound originating in the transmission extension housing. Thermal expansion can potentially damage a pre-loaded bearing, causing the noise.

Q: I have a 2007 Dodge Caravan with the automatic door lock feature. When I drive in the rain, the locks start locking and unlocking rapidly for 60-90 seconds then quit for a while, then do it again. This continues even after removing the key but quits after being parked for a while. I tried to disable the auto lock, using the instructions in the manual, but was unsuccessful. There is no separate fuse that controls this. Any thoughts?

A: Water/moisture is grounding the electrical circuit that operates the locks. A scan tool should be able to identify specific fault codes with the power door lock system, but you could try "watering" each window for a minute or so, one at a time, with a garden hose. Water may be getting by the window seals, running down the inside of a door and grounding the circuit, causing the rapid cycling of the locks. This may help you pinpoint which door or cylinder lock switch or connector is getting wet.