# 2000 Sentra PO171 code but MAF not fix problem



## jacob.fitzpatrick (Jul 29, 2009)

Hello all

About 2 years ago my 2000 Sentra had issues bogging down on acceleration with a PO170 code. I replaced the MAF and fuel pump and all was good.

Just now my car has the same problem. it will not accelerate past 2500RPM without what seem like a "rev-limitor" kicking in. the car wont go past 25mph. check engine light is on with the same PO170 code. My meter reads 0grams on the MAF so I replaced it once again. The car ran great for 1 day then same problem, it wont exceed 2500 RPM.

Any suggestions?


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## smj999smj (Jan 1, 2006)

I'm assuming you mean P0171 as there is no listing for a P0170 code. If your MAF is reading 0 grams, I would suspect that either the replacement MAF has failed or you have a circuit issue between the MAF and ECM.


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## jacob.fitzpatrick (Jul 29, 2009)

Sorry. CORRECTION its the PO100 Code not po170

Any suggestions on how to test the wireing from MAF to ECM. 

Is there a relay or fuse somewhere?


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## jdg (Aug 27, 2009)

P - "ZERO" - 100
not
P - "OH" - 100

If you've tried Googling it and come up empty, that's probably why.
If you haven't tried Googling the problem...why not?

Testing wiring? Get a meter or a test light...and a wiring diagram...and a Haynes or Chilton's manual or a Factory Service Manual.

And not revving past 2500-ish rpm is normal operation and is programmed into the ECU to do that if the MAF signal is jacked up. Helps keep other stuff from blowing up.


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## smj999smj (Jan 1, 2006)

Do NOT use a test light to test the MAF circuit! Use a low-impedance multimeter. Haynes manuals probably won't be much help as they are typically for general repair and maintenance procedures. Your best bet is a factory service manual, which will also give you the test procedure for a P0100 DTC along with the pinout diagrams for the ECM and MAS harness connectors and wire colors. When testing ECM circuits for shorts/opens/resistance, make sure you unplug it from the ECM, first, after disconnecting the battery.


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## jdg (Aug 27, 2009)

smj999smj said:


> Use a low-impedance multimeter.


Don't you mean a "high-impedance multimeter"? 

A low-impedance meter will pull a load on whatever circuit it's testing...'cause that's just the nature of the beast, a meter movement with a coil, a shunt, and so on...
High impedance (i.e. op-amp inputs, A/C coupled inputs, and so) meter draw current as little as a few micro-amps and use op-amps configured as either buffers, differential, or following amplifiers with the resultant signals being fed to various ADC circuits for display. Blah-blah-blah. Big words eh? 

True about the Hayens/Chilton's manuals, but with that said, the Haynes/Chilton's manuals I've got for my B14 have the MAF wires in the wiring diagrams, and jeez, I would hope a person would have enough sense to disconnect the 'boxes' at each of the wires to check the wire itself.
If not, maybe said person shouldn't be messing with such wires...


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