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Using the Colour of Your Car's Exhaust Smoke as a Diagnostic Tool

When was the last time you paid any attention to your car's exhaust smoke? If you're like most drivers, you may seldom notice what's coming out of the muffler of your vehicle. However, it's a good idea to regularly check these emissions. If there is an engine problem, the colour of your car's exhaust smoke can give you an idea as to what might be wrong.

Of course, if there is any sign of trouble with your vehicle, you should make an appointment with your preferred service centre immediately. And if you pay attention to things like the exhaust, you may be able to get your car to a technician before the issue gets worse.

Knowing which Exhaust Smoke Colour Indicates what Problem

Car's Exhaust Smoke

Another reason to be mindful of the hue of your vehicle's exhaust smoke is that if you see lots of smoke, you may not immediately panic if it's one colour vs. another. An excess of exhaust emissions generally means that something is wrong with the engine. But it could be something relatively minor.

Here is a breakdown of the different exhaust smoke colours and what they could mean.


This one is difficult to notice because a car with a healthy engine often emits white smoke. But if you see white smoke that is extra thick and doesn't quickly evaporate, this may not be normal. Generally, thick white smoke means that there is coolant in a vehicle's combustion chamber. It probably migrated there due to one of three reasons:

  • Blown Head Gasket
  • Damaged Cylinder Head
  • Cracked Engine Block

Fixing a blown head gasket requires a fairly minor procedure. But if the cylinder head is damaged, the whole engine will need to be overhauled. In the worst scenario, a cracked engine block, the entire engine will have to be replaced.

Blue or Grey

If you see blue or grey exhaust smoke pouring out of your muffler, it most likely means that oil has leaked into the combustion chamber. This is most likely the result of:

  • Leaking Valve Seals
  • Excessive Clearance Around Valve Guides
  • A "Blow-By" Caused by Worn Piston Rings

If the issue causing the oil leak isn't addressed, you will start to notice poor fuel economy, bad acceleration and rough idling. Your car will also be losing oil, and this could cause even more problems.


Your vehicle's combustion chamber requires some fuel to function properly, but too much fuel isn't good. In fact, there should be just the right mixture of fuel and air. If there is too much air, then the mixture is said to be "running light." On the other hand, an abundance of fuel results in a mixture described as "running rich" and black exhaust smoke. Here are the reasons why too much fuel might be getting into the combustion chamber:

  • Leaking Injectors
  • A Dirty or Clogged Air Filter
  • Improper Ignition Timing
  • A Faulty Sensor
  • A Bad Fuel Pressure Switch

Any of these issues can cause your car's engine to run rough and your gas mileage to drop. If left unrepaired over a long period of time, the engine might incur serious damage and need to be overhauled or replaced.

Getting the Right Help when it's Time for a Newer, more Reliable Car

If your current vehicle has served you well, but no longer runs the way it should, it might be time to get a better car. Those repair bills can add up, so buying a newer vehicle might be more cost-effective in the long run.

If this describes your situation, but you're worried that your poor credit will prevent you from getting approved for an auto loan, Canada Auto Loan can help. We can match you with a dealership in your area that can work with your situation. Our service is fast, free, and comes with no obligations.

Go ahead and fill out our simple and secure online application to see how quickly we can get you back on the road.