I had the same problem with my 1988 Cutlass. What you should initially do is check the key that you're using. Is it old or worn? If so, it could very well be the key you are using. I suggest that you get a new key made just to be sure. If this isn't the case, then I'm afraid I'm unable to help. Good luck.
The oxygen sensor on the 1999 Oldsmobile Cutlass Sierra is located on the lower exhaust. If you need to replace it, they are available for about $20 online.
I'd call a locksmith. They will be able to tell you the exact problem and how to fix it.
DEX-COOL
None
The 1999 Oldsmobile Cutlass OBD 2 port is under driver side dash left of steering column
dextron / mercon type 2
Begin by loosening the tensioner pulley on your 1999 Oldsmobile Cutlass. Put your serpentine belt around the pulleys. Tighten the serpentine belt with the tensioner pulley.
You fill the radiator through the overflow tank.
take the complete headlight assembly loose or out to get to the bulb.
Follow the top radiator hose down to the water outlet on the engine; the stat is in there.
Just like the radiator on the 1966 VW Beetle.... because neither exits. The last American carbureted auto engine was a 1990 Oldsmobile.
Replacing a thermostat on a 1999 Oldsmobile Cutlass is very easy to do. First you will find the thermostat by following the upper radiator hose. It is under the exhaust crossover. The thermostat has two 13 mm bolts holding it in place. Take the bolts off to remove the thermostat and replace with a new one.