Why is warning light on, after putting new starter on Maxima?

[retracy]

I drive a 97 Maxima. I have been having trouble starting it, and up until a couple of days ago, we could jump it with another car. Then, it wouldn't start at all. I took it in, and they told me I needed a new starter. They put it in yesterday. I picked the car up after they had closed. It started fine, but there was a warning light on the far right hand side of the control panel. I took the car back to them this morning, and they told me it was code PO 325 (Knock sensor code) and P1 335 (Miss fire code). They told me it would cost about $400 to repair the sensor. Of course, I was upset. I never had the problem before I took it to them. They said they could reset the sensor, and that it might help, but it might come back on. They reset it, and it went out. I have driven it all day, and so far it has not come back on. What caused this, and do I need to worry about it coming back on.

Thanks for any help. I don't know much about cars and hate having car trouble.

[rather_b_boatin]

If it does not come back on don't even give it a thought. You'd most likley know if the engine was knocking. (bad gas, or lifter knock you can actually hear) It is strange that it came in right after service. $tealerships always offer some completely off the wall repair w/ an unbelievable price tag. It is possible, if the light does come back on, that it is coincidence that the problem came up at the same time as the service. I would not loose any sleep over it at this point.

[Nahkapohjola]

Originally Posted by retracy

... I don't know much about cars and hate having car trouble.

Only few want trouble. And most of those, want it to smbdt else...

As said, error codes dont mean much if they do not repeat and no actual problems. Some do charge resetting the code: DIY take batt OFF for 30 min.
Read this: http://www.cardomain.com/ride/748507/14

Knock, misfire: One possible reason for such codes might be bad gas. Another is soot buildup in the engine. Maxima engine is very low rpm, and if it is always driven very slow, gas exchange is slow... It is good for the engine smtimes to let gases fly: hit the pedal in bottom, drive a minute with 1st gear on, high rpm. And change plugs.

Do not jump start when donor batt is connected: High possibility to fry donor alternator rectifier.