Saturn won't start up intermittently

My daughter’s 2004 Saturn Ion3 has had problems starting up for three weeks. Battery was replaced as was the crank shaft sensor. Mechanics cannot make it NOT start so they can’t diagnose any more. My daughter goes out in the morning, the car won’t start, it just makes a spinning noise, then waits 15 min and sometimes it will start. Sometimes turning the key again right away will cause it to make NO noise at all. What else could be wrong?

Not being able to reproduce it is a problem. What you’re left with is guessing.

You’ll want to try to clarify for folks here is what kind of non-start problem it is. One might replace a battery if you turn the key and get nothing - or maybe just some clicks or a very weak turning of the engine (that very tired sounding rrrrrr…rr.r…r…r…).

But one would replace a crank sensor if the car cranks over just fine (good healthy RR.RR.RR.RR.RR.RR) but won’t start.

So are you saying that it is sometimes one kind of problem, but sometimes a whole other kind of problem? “Spinning noise” could mean a lot of different things so try to post a better description.

If spinning noise does not involve the engine actually cranking over then I’d be looking at the starter.

Presumably whomever replaced the battery gave the terminals a good cleaning and made sure they were reinstalled nice and tight. Has anyone pulled the connections at the other end? At the starter for instance?

Depending on what exactly is going on one might also look at the ignition switch and/or the neutral safety switch. (The latter is easy to check out by putting the car in neutral and then trying to start it).

Anyway - without a clearer idea of what the car is doing it leaves too many possibilities open.

Spinning noise = starter or ring gear.

What you have here is a very common problem in saturn ions. Its called a passlock sensor failure. The passlock sensor is in the ignition switch, and when it fails, as it has in your vehicle, it essentially thinks you are stealing the car or have inserted the wrong key. The only solution to this problem is to have the ignition switch replaced and the passlock sensor reprogrammed. I’m 99% sure this will fix your problem, if not you might want to look over this list of common no start issues