Possibly the silliest reason that your check engine light is on a loose damaged or missing gas cap may cause your check engine light to come on.
Toyota tundra gas cap check engine light.
I can not find a leak and the truck runs great.
The gas cap seals the fuel system maintains pressure and will reduce emissions.
I have a 2000 tundra and the check engine light comes on as soon as the gas tank is less than half full.
If you have a loose or damaged gas cap not only will your check engine light go on but you can lose fuel through evaporation.
A quick and easy fix make sure to check your gas cap if your check engine light illuminates.
I had it reset several times but it always comes back on at 1 2 tank.
Your vehicle s oxygen sensor might require replacement.
You can either tighten the cap and wait for the system to reset itself when it determines the problem is fixed or you can use an obd ii code scanner to manually reset the system.
A properly sealed gas cap maintains pressure in your fuel tank and prevents harmful fumes from escaping.
I ve replaced the gas cap and always make sure it is tight.
The check engine light alerts you to a loose broken or missing gas cap so you can tighten or replace it before you lose too much fuel through evaporation.
Step 1 turn off your vehicle s engine.
Toyota check engine or service engine soon light may come on due to something as simple as a loose gas cap but it can also be an indication of a number of other issues including bad spark plugs faulty oxygen sensor dirty mass airflow sensor and even an early indication of a transmission problem.