I just bought a 2005 Nissan Altima 2.5s 4 cylinder. I've had the car less than a week but I've noticed while sitting in park with the heat on the engile idles up ever so slightly. It does this every minute or so. Is that normal?

Clean the Idle Air Control Valve (IACV), throttle plate, and throttle body:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-selected-other-vehicles-46563-7.html#post1054149

Afterwards, replace the air filter.

Clean the Idle Air Control Valve (IACV), throttle plate, and throttle body:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-selected-other-vehicles-46563-7.html#post1054149

Afterwards, replace the air filter.


Thank you very much. Is it harmful if I don't do it right away?

No.

Here are some maintenance tips that might help you:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-selected-other-vehicles-46563.html#post219991