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Nissan Sentra Service Engine Soon Light - Quick Question - I know what code Indicates

I have a manual 2000 Nissan Sentra with 101,000 miles. The Service Engine Soon light stays on. I was told it was an vacuum leak or mass air flow or basically the mixture of oxygen is off. (I already had one mass air flow put in a few years ago.) I have been ignoring the message. We went camping and drove twice to 9,000 feet. No problems on road at all. The car runs great. In fact we got 35 mpg on the trip. Am I possibly hurting the car by ignoring the message? Thanks.

Yup, you are possibly hurting the engine.

So, what DOES the code indicate? What exactly IS the code?

You do realize, of course, that a lean cylinder can burn a hole through a piston…too much air for the fuel is like using a bellows on a fireplace…you can burn a house down if you continue blowing excess air in the fireplace. More chimney liners have cracked that way…

The same mountainbike couldn’t have explained it better. Sure, you’re getting great gas mileage, but at what cost? Do you have any idea what it would cost if you, in fact, burned a hole in a piston? Trust me, it would be thousands of dollars, and I seriously doubt you want a repair bill like that.

You should NEVER ignore the SES light. It’s an early warning system, meant to alert you to a developing problem while it’s still simple and inexpensive to repair. You ignore the light at your peril, and the peril of your pocketbook.

The “meanings” you gave for whatever code is stored in your car’s computer are vague, and unless you tell us the exact code we can only guess.

Take the car to a competent mechanic, let him or her diagnose the ACTUAL cause of the problem and fix it. Then you can drive on without worry.

You need to post the code. One thing to check on a Sentra, especially the B15 model is the connector for the rear O2 sensor. It is prone to getting water in it because of its location.

First of all, THANKS.

The codes were P0171 System too lean (Bank 1)
PO171 System Too Lean (Bank 2)

I guess I’ll take it to Nissan because I once took it to another guy and it took him forever to get the mass air flow working.

There may be a leak in the vacuum system that is causing the error or the O2 sensor may be faulty. Problems like this should be fixed as soon as it is practical because other things can occur and you wouldn’t know about it since the warning light is already on. Some problems can cause damage to the sensors and the CAT if they are ignored for too long.