Do it yourself
Frequently asked questions about cars and motorcycles
Car tutorial (Do it yourself) Motorcycle tutorial (Do it yourself) Frequently Asked Questions

The Meaning of Exhaust Gas Colours

Model: (Various brands) Various
Part: Checks and maintenance

Let’s see how to perform a preliminary visual diagnosis of problems with your car by examining the colour of the smoke coming from the exhaust. Thick, persistent white smoke indicates a problem with the coolant entering the combustion chambers. It signals a possible damaged head gasket. Blue or bluish smoke indicates engine oil burning in the combustion process, suggesting wear on the seals or piston rings. Grey smoke indicates excess oil or a transmission fluid leak burning. Black smoke indicates a fuel/air mixture that is too rich (too much fuel and not enough air), common in diesel engines or with injection problems.

Posted on 16 April 2026 by ScegliAuto

Video tutorial

Related tutorials

How to Clean the EGR Valve Without Removing It
How to Clean the EGR Valve Without Removing It
(Various brands) Various The EGR valve functions to reintroduce some exhaust gases back into the intake to reduce NOx emissions: constant contact with exhaust gases, which ar…
How Does a Vacuum Pump Work?
How Does a Vacuum Pump Work?
(Various brands) Various Vacuum pumps are installed in vehicles that do not have sufficient vacuum. Diesel engines, on the other hand, are equipped with vacuum pumps as stand…
How does the diesel EGR system work?
How does the diesel EGR system work?
(Various brands) Various In this short video, we see the operation of the diesel EGR system with the role of the MAF sensor and the throttle valve: the MAF constantly measure…

Other guides you may be interested in

    Frequently Asked Questions

    • Vari - What does it mean when the message "insp" appears on a car? Read answer
    • Vari - What problems does the Kymco Downtown 300i have? Read answer

How to Open the Bonnet on the Lancia Y

To open the bonnet on this vehicle, follow these simple instructions: first, open the driver's door and locate the lever positioned just below the dashboard, marked with an image of the vehicle with the bonnet open. Pull this lever towards you until you hear a "click" indicating the bonnet is released. Next, exit the cabin and stand in front of the bonnet to disengage the safety catch and complete the opening. To do this, slightly lift the bonnet, locate the yellow lever underneath, and pull it to the left to fully release and open the bonnet.

Watch the video!


by ScegliAuto

More videos