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Code 100 2001 Nissan Sentra

I have a 01 Sentra with a 1.8l It runs rough over 2000 rpm( very bad hesitation). The code is 100 which is a MAss air flow sensor. We replaced it - still gives us same code after replacing the part. Same symptoms also… any ideas other then maf sensor??

The problem is that the code only tells you that there is a problem in the MAF circuit. It doesn’t tell you that the MAF is bad. It might mean that the MAF is bad but you have to actually test stuff.

So lets assume for a moment that the new MAF you bought is good (i.e. not bad off the shelf) - you can figure the MAF itself isn’t the problem - and expensive way to “test” parts. Anyway, now you move onto the wiring for the MAF - its connector plug & follow the wires backwards looking for signs of problems. If you get a repair manual for the car (most any auto parts store) it will tell you how to test things.

Thanks for your help… we (the mechanic) did start tracing the circuit back… I was wondering if there are any common pitfalls to look for with this car… perhaps an area known to have a wire come loose or something like that… wishful thinking I guess …

After changing the MAF, you did reset the CEL and hook everything back together, didn’t you. If the stock isn’t in place, or the duct work isn’t properly clamped up, that might give you a bad indication. Otherwise, there isn’t too much to that system. The MAF sensor send a signal to the computer, telling it how much air is flowing past it, and the computer makes adjustments based on that. I’m assuming your MAF is installed correctly (I don’t know if it’s possible to install them backwards?), and everything else is hooked up. The MAF sensor gets a signal(usually voltage and/current) to heat up a single wire (or grid) and as air flows past, it cools, so the as it is trying to keep the wire (or grid) heated up to a certain temperature, it has to constantly vary the voltage signal it sends. THe more air that flows past the MAF sensor, the more voltage thats required to keep it at a constant temp. THe computer reads all this and is continously making adjustments. Course this is all in closed loop. There is usually a default signal in open loop. It is quite a genius system in my opinion. You need to start chasing wires at this point if everything else checks good.

yep I guess it is chasing wires for me- we did reset the cel and it tripped the same code instantly. Everything else looks o.k. IT remains a mystery…

I’d make sure you don’t have any blown fuses. Then grab hold of a good wiring diagram and start shooting wires from the MAF plug, there can’t be that many wires to check out.

you are right - I think there are only 4

Thanks very much