Does the OB system for my 96 Camry 2.2 report missing. gas cap?

Question

I could smell gas when gas tank was full. The smell came from the gas cap area. I took a chance and replaced the gas cap. The oder is gone and the rough idle stopped. Should the computer have thrown a code?

Answer 1

Yes it will throw a code it would be both a Vent code and a Purge code. It would be a P0440 and a P0446. The reason it would not throw a code either the fuel level is less than 1/4 full or more than 3/4 full. The ECM look for open short and rationality. If you ever cleared a CK ENG LT and have to set monitor the difficult of all monitor is the EVAP system. It take time or days before the ECM notice when there is a fault in the EVAP system