2000 Nissan Sentra mystery starting problem

We have a 2000 Nissan Sentra that occasionally won’t start. This first started a couple weeks ago when it had been raining really heavily for two days. Just when we called AAA for a tow, the guy arrived and had a look - what do you know it started. It worked fine for two weeks or so.

Then we went away for 2 weeks and when we returned from vacation it wouldn’t start. It had been sitting still and it had been raining.

My husband had it towed to a local garage and they said it’s not the battery, fuses, or spark plugs. They had trouble getting power to the computer and thought it may need a new computer. They removed the computer, put it back in, it magically started. They never did figure out what was wrong.

For a week it drove fine. Then it wouldn’t start. This time we had it towed to the Nissan dealer. They said it needs 4 new oxygen sensors, a new catalytic converter, and a new front exhaust pipe, parts & labor will come $2400. BUT! None of that is related to it not starting. They don’t know why it wouldn’t start because it started for them. So somewhere in between our house and the dealer, it magically corrected itself and started.

This car is 10 years old and has 165,000 miles on it. I can’t see spending $2400 and still not have the actual problem of it not starting be resolved. They were going to try and start it today, as it’s been sitting out in the rain, and perhaps if it fails to start, they’ll be able to figure it out.

What could be the problem? $2400 seems like a lot, even though I realize those parts aren’t cheap, I think it could be done cheaper elsewhere. Is it even worth repairing or should we take it while it’s starting up and just try to trade it in for a new car, paying the dealer $100 for their time so far and hope for the best?

Any codes pointing to O2 sensors and converters are likely the symptom of something else.

Odds are this is related to the secondary ignition; spark plugs and coils.
Put a new set of spark plugs in it and make sure that the coils are coated with dialectric grease at all points.

In a nutshell what happens is this. Moisture in the air provides a pathway for the ignition spark that is much easier to travel when compared to the path the spark has to take when it jumps the spark plug gap in a cylinder that is under high pressure.

The spark always takes the easiest path to ground and moisture can provide that path.
That’s simplified and I hope it helps.

When it runs, is the Check Engine Light on?


So do you think that replacing the spark plugs would cause those codes to stop appearing? I sure would like to not spend that money right now.

Your explanation makes sense to me and sounds so simple. How come the guys at the garage couldn’t come up with that? The first garage charged us only $42 but they had it for a week and had no answer for us. The dealer has had it for a day and comes up with a $2400 answer that doesn’t solve the problem.

You don’t think it’s time to get rid of it?

Update to this, the mechanic tried it out a few times throughout the day and each time it started without any trouble. I told him I’m sure he’s right about the codes showing the need for those parts but I simply don’t have $2400 to spend right now and if it’s starting, could we drive it away - is it driveable. He said it was and offered to try it again in the morning if we couldn’t get over there before they close tonight. So that’s what we’re doing.

It’s been drizzling, foggy, or raining all day today and the car has been outside. I just don’t get it.