Nissan Repair Questions? Ask a Mechanic for Answers ASAP
What you describe sounds like a bad cam sensor. When they go bad they will set the p0340 code and will have a hard time starting. Do you want to attempt to fix this yourself? The cam sensor is fairly easy to replace.
Anytime the computer (PCM) detects a fault in any of the engine control systems it will trigger the TCS and slip light. This vehicle uses engine timing to operate the traction control system. If you are losing traction the PCM adjusts the engine timing to control the slip. So to prevent the engine from malfunctioning it turns off the traction control system and turns on the TCS and slip lights.
If the catalytic converter is failing it pretty much just means that one of the cats isn't working as efficiently as it should be. This code could be a false activation because of the cam sensor issue.
Take a look at this diagram. It shows the location of both cam sensors. It's usually a good idea to replace both of them. If you have a good scan tool and a lab scope you can check exactly which sensor might be bad, but most of the time you end up replacing both of them anyway.