Q: P0302 code & car makes puttering noises

Hello. The P0302 diagnostic trouble code indicates that a misfire has been detected on cylinder 2. Before changing the IAC valve, it would be a good idea to address the P0302 diagnostic trouble code and have the spark plugs, spark plug wires, ignition coils, or ignition control module inspected. This may solve the problem. If you aren’t getting a diagnostic trouble code for the IAC valve, then it may not need to be replaced. The P0302 trouble code is commonly resolved by having a tune up completed on the vehicle. Keep in mind that there are times when this trouble code is caused by a faulty fuel injector, burned valves, or a dead engine cylinder. I would suggest that you have an inspection of the misfiring condition completed by a certified technician, such as one from YourMechanic.