Blue smoke from ML320

Last Saturday I was driving my 1999 Mercedes ML320 SUV (163,000 miles) on a highway in California (for about 70 miles) when suddenly I saw a huge cloud of smoke behind me but I didn’t hear any noise and didn’t notice any change in car driving. I was not sure if it was my car or somebody else car. On Sunday I was driving on a city street and suddenly I saw the same smoke but not of that extent but with a rattle from back side of the car. I quickly stopped on a side street and saw whitish/bluish smoke from the tailpipe. In a couple of minutes the smoke disappeared and I drove the car back home. No more smoke since then. I checked the code and it showed P0700 (is there for a couple of months) and P0442 (new code). I called a couple of mechanics and one checked the car but none knows what caused the smoke. The mechanic said that P0442 is not the cause of the smoke. The engine oil is still good and to the max. A mechanic recently replaced the EGR valve. Any suggestions are appreciated. Can I drive the car or I might do more damage.



P0700 means something has tripped an error code in the transmission control computer. You need to have the transmission computer scanned in order to find out what that code is.

P0442 is evaporative emissions fault. The most common cause is forgetting to tighten the gas cap properly when you get fuel.

Think hard about the color of the smoke. It’s important. White = coolant. Blue = oil. If it’s blue, then you’re burning oil. That’s not exactly awesome news, especially in the amount you described, but it’s not as bad as sending coolant out the tailpipe, because that means a blown head gasket.

How often do you change your oil?? Sludging can cause this by plugging up the oil return passages in the head. The valve cover then fills with oil and it will find its way down the valve stems and into the engine…creating the big blue cloud…You would have to remove the valve-cover to verify this… Also, have the PCV system checked from end to end…Problems here will cause oil to be fed into the air intake resulting in lots of smoke…