I purchased a 1999 Toyota Tacoma that had a check engine light. I used my obd tool and a application on my Smart phone called Torque. To scan my vehicle’s computer If you don’t have one you can buy one. They don’t cost that much online. Or you can have your local automotive parts store scan your vehicles computer to find what codes you have.
I used my obd tool to scan my vehicle’s computer to find out I had a p0441 code. Which is a Issue With evaporator emissions control system. I first started looking in the engine compartment inspecting The Rubber hoses for Damage due to the age of the vehicle. I was looking for cracked or broken hoses upon further investigation. I found a hose that was jammed in between the air filter housing. That probably happen when they replaced the air filter. It completely restricted air flow to my evaporator emission control system. I was very lucky mine was as simple as reconnect in the hose in general. It’s a good idea to thoroughly inspect all hoses make sure they’re not cracked or dry rotted,broken or disconnected as in my case.
See photo showing hose smashed inside of air filter housing.
See photo showing hose reconnected.
See photo showing other end of hose connected to evaporator emission control.
Please see the brief video I made