Yesterday I changed air filters in my car (Nissan supper saloon N16 - model year 2000). After installation the check engine light came on when I started the engine and the engine seemed to be running with less power. Then I thought it could be a problem with new air filter so I replaced it with old one. I started and stopped engine few times and check engine lights went off.

After check engine light went off I drove few miles with less power and it recovered as I drove.

Today morning lights came back on. The engine seems to be producing less power. I suspected that oil or something from the new filter might stick on the MAF Sensor rods. I cleaned it too by blowing air but I am still having the problem.

I still have not checked for OBD readings.

What could be the problem?

Any suggestions?

Is there anything to do with MAF sensor?

update When I open the fuel tank lid it depressurized giving a vacuum sound? Does this indicate some EVAP system error?

I do not have an OBD reader and have to travel long distances to reach a automotive shop.

Is there anything I can try at home?

Error code (update) i got code p0100 so i replaced the MAF sensor but still check engine lights are on.

  • 1
    Without the codes, it's a shot in the dark. Get the codes and let us know. May 15, 2016 at 10:47
  • 1
    also recheck your work maybe a vacuum hose or the or hose tube came loose.
    – Ben
    May 15, 2016 at 12:00
  • @Ben when i open the fuel tank lid, it depressurized giving a vacuum sound ? does this indicate some EVAP system error ?? i do not have obd reader and have to travel long distance to reach a mechanical shop. is there anything i can try at home ??
    – Milan
    May 15, 2016 at 16:38
  • @Milan it's normal. Get your codes read. May 16, 2016 at 10:22

4 Answers 4



A code P0100 may mean that one or more of the following has happened: The MAF may be disconnected, or a wiring connection may be bad The MAF sensor may be faulty

If the MAF sensor element is dirty use disc brake cleaner. Do not use Throttle body cleaner because it will leave a residue that will muck up the sensor. A residue on the hot wire element will render it useless.

Check the connection as well.


Milan, I recommend that you purchase a paper Chilton's or Haynes repair manual for your car. They cost around $30 at your local autoparts store. Many manufacturers have provided a 'secret' code that you can use to turn your check engine light into a blinking code reader. The instructions for that tend to be written in the repair manual (not all manufacturers do that but many do... for some you may need a light bulb tester or a multimeter.)

Do note that in many locations, your local autoparts store will read the codes for you for free. (Oops. not offered in California, not sure why...)

And as for @resident_heretic and the vacuum sound, er.. yeah, kinda, sorta. But not really. Here's my complete answer from another posting... Its a lengthy answer. And no matter how hot the days, nobody wants fuel vapor escaping.. that's a major no-no for an automotive manufacturer.

Update: Here's the secret code to read the engine computer for a Nissan Maxima (not sure if that's the same for you, but you get the idea...)

  • Gas caps check valves do fail because It happened on 2001 Corolla and this remedied the problem.
    – Old_Fossil
    May 15, 2016 at 20:25
  • I'm nearly positive there is no check valve in that model year gas cap. There is a clutch mechanism to ensure you don't over tighten the thing. There is a seal, that well, has to seal. And that's it. Clearly if your gas cap leaked at the seal, that would absolutely set a check engine light, and you'd have to replace the gas cap. But that's it. So absolutely, yes, gas caps fail, and when they do they set a code. But there is no check valve in side. Its just a solid seal device. With the emissions rules of this century there is no way there is a check valve in there.
    – zipzit
    May 15, 2016 at 20:35

enter image description here

This is gas cap check valve. I tried to edit my post but It would let me. So here is a follow up for clarification. The check valve in the gas cap helps to regulate the pressure in the EVAP system.


Regarding the whooshing sound when you remove the gas cap. This could be a defective gas cap check valve. The check valve performs 2 functions. When the fuel pump takes fuel from the tank the fuel volume decreases creating a partial vacuum inside the tank causing the fuel pump to work harder. The check valve injects outside air in to equalize the pressure in the tank while the fuel pump is is in operation. When the fuel pump stops the check valve closes. A normally conditions a functioning fuel cap shouldn't make any noise at all , the exception being on very hot days -fuel vapor escaping. Change the gas cap with an OEM one.

  • The whooshing sounds on hot days is when you loosen up the cap to refuel .
    – Old_Fossil
    May 15, 2016 at 21:36

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