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My 2001 Nissan Sentra shows a P0171 and P0101 code.

I tried to clean the sensor and the part after that (I don't know the name) and it's still showing the engine light. The sensor seems like new to me and I want to know if I really have to change it.

Also is it safe to drive for 16 hours with this problem?

  • Did you clear the codes after cleaning the MAF sensor? – Zaid Aug 28 '15 at 10:44
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You may have already fixed your problem

You may need to clear the codes for the Check Engine Light to go away. It may be that the sensor is clean but the check engine light is being shown because it's retained in the computer's memory.

Once the codes are cleared, see if the CEL stays off or if it returns.


If the issue returns

  • P0171 is saying that the system is detecting too much air compared to fuel.

  • P0101 is saying that the ECU doesn't like the measured value of air flow coming from the MAF sensor.

Based on these two codes it looks like a clear case of the MAF sensor needing replacement. Cleaning doesn't always do the trick, especially if the MAF sensor hot-wire element has a lot of dust/dirt accumulation.

One other thing to consider is the possibility of a problem related to the wiring of the MAF sensor, which could explain the codes as well.

To see if this is the issue, it's a good idea to have the MAF readouts inspected with a scan tool:

  • A "zero" reading would indicate a wiring issue
  • If the readout values change with RPM then the codes are because the sensor is fouled and needs replacement.
  • You would need a pretty good scan tool to read the values of MAF. I don't think the basic ones allow this functionality. Is it possible to use a multimeter instead? – rana Aug 28 '15 at 13:15
  • @rana : I only have a basic scan tool (OBDII Wi-Fi scanner + iPad application) and can get MAF readings. The refresh rate may not be amazing but it's more convenient than bench testing a MAF or probing voltage across it for most people. – Zaid Aug 28 '15 at 13:33

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