My 2000 chevy malibu is reading p0302 p0241 and p0442

It means there is a leak in the e vac system

Evap leak..... more than likely it’s an evap sensor or solenoid that’s is the problem.

Go to Autozone ( or similar). They will read your code(s) for free and print them out for you too.

The p0302 is a misfiring code. It could be plugs or coil pack. The p0420 code reads Catalyst System Efficiency Below Treshol. I would start with the plugs that is the cheapest route to start out with.

Could be a faulty gas cap or running the engine with the gas cap off - or a leak in the line from the gas tank to the vent canister, or a leak in the gas tank.

you can try this, if it is the original radio. call or visit a dealer and provide proof of ownership. and they will give you code, you can also go to www.radio-codes.com but cost is about 8.00 to get code.

if this is a factory radio, then you can go to dealership, to get unlock code for your radio. i think you may need the vin number.

Here's a link to the routing diagram you need...
http://www.gates.com/common/part_locator/view_diagram.cfm?id=S8015

take key fob to a cparts store , most have a tester on the counter

"This indicates a fuel vapor leak in the EVAP control system. It means a very small leak has been detected. In fact, the leak can be from a hole as small as 0.04" in diameter. The (EVAP) emission control system prevents the escape of fuel vapors from a vehicle's fuel system. Fuel vapors are routed by hoses to a charcoal canister for storage. Later, when the engine is running a purge control valve opens allowing intake vacuum to siphon the fuel vapors into the engine."
Hope that helps..