Diagnosing Different Exhaust Colors

We all recognize colors when we drive on the streets. Green means go; red means stop, and yellow means caution. Traffic lights that we see are bound to change colors as they are designed that way. However, what if you also experience changing colors when it comes to your exhaust smoke?

There is a lot of possible aftermath of that smoke coming from your vehicle and it may even cause oyu inconvenience on the road due to engine failure. If this happens, you might start to ask yourself, “is it safe to abandon my vehicle here?” “Where should I get help?” “Are there tow truck near me?” You can possibly prevent this when you are able to diagnose your car right before it completely fails, and one way to do that is to identify the cause and possible effect when your vehicle gives off A certain smoke color.


This article is intended only for diagnosing gasoline engines. If you have a diesel engine, it is better to consult a professional technician for appropriate diagnosis and repair.

1. Thin white or plain white exhaust smoke

Diagnosis: your vehicle is in normal condition, as this white smoke just means water vapor. You can always see it whenever you start your vehicle especially in colder days or environments. The smoke happens due to the condensation collected in the exhaust system.

2.Milky white to gray exhaust smoke

Diagnosis: not normal.

When a greyish and milky white exhaust smoke is persistently coming from your tailpipe, this could mean potential damage in your car, and most probably because of a leaking head gasket. A coolant leak in the summer may lead to an overheated engine and this could create a lot of problems.

Another probable root cause of this is a cracked block or cylinder head, and these two issues impose a serious damage to your vehicle. When you fail in addressing them, you might end up having more expensive repairs or replacements.

3.Black smoke from the exhaust

Our diagnosis: not normal

There are many potential reasons for this such as malfunctioning fuel injection system, clogged air filter, blocked manifold, or other damaged parts of the vehicle. These all induce the vehicle to burn too much fuel that leads to exhaustion.

A clogged filter does not really impose a threat to your vehicle but you will certainly suffer form its poor performance.

4.Blue smoke from the exhaust

Our diagnosis: Not normal

This blue smoke can also be in a greyish form, and these usually mean that your vehicle is experiencing some oil leak and that it burns too much oil. It is important to call a professional technician to check your vehicle as it can lead to very serious damages and problems like damage piston rings, valve seals, and others.


A blue smoke that comes out during vehicle acceleration means that your piston rings are damaged. During deceleration, a blue smoke may mean the cylinder head’s valve is damaged. It is better to call a technician to have an accurate diagnosis of the issue and to provide proper interventions