Pontiac Repair: 98 sunfire 4 cylinder, 5speed, cam sensor, gas mileage

Question
I have an emission light on and the guy I bought it from told me it will do this for the gas cap. I had the car one wk and after the first fill up the light came on.  I adjusted the cap but no luck. I took it to the mechanic who tells me 2 codes come up. First cam sensor, 2nd cadillac converter. The bill is around 700 dollars. He states the cam sensor will leave me stranded if I don't fix it now. He states the cadillac converter can wait but will plug the engine, cause a bad smell and get bad gas mileage.  It drives fine now, theres not even a hit of a smell and my gas mileage has been around 35 mpg.  Is this something I can put off ?? They didn't pick up a fuel cap sensor eihter. Should I wait to see if the lights come back on after being cleared?

Answer
Hi
The cam sensor code could leave the vehicle in a no start situation.
I would drvie and AS SOON as light comes on, take it have codes scanned and see which one set. Codes can stay in the memory for up to 40 drive cycles before they clear on their own. So those codes could have been stored 39 drive cycles before you had it checked. Understand? A drive cycle is not just a start the car. It is a certian set of tests the PCM preforms. I would drive it until the light comes on, then as soon as possible take it to shop and have them checked.
You can also shop around.... get prices from different shops on the converter.
I hope this helps
Good Luck
God Bless
Pawl