# 1998 200sx MAF and P0105 code?



## mbz321 (Aug 14, 2009)

Ok, let me start by saying I am a car n00b...just trying to diagnose what is wrong here.

I have a 98 200sx 1.6 L that has been throwing me a P0105 code (pulled at Autozone and manually with the ECU), which shows faulty map sensor. So far I have:

1.) removed the sensor and sprayed with electric parts cleaner, checked the connectors and they appear okay. Replaced sensor, reset the code. Restarted car, light went away but came back on less than 10 seconds later.

2.) I purchased a used MAF on ebay, didn't try cleaning it but seller claims it's in working condition. Put that in, reset the code again...and light still came back on!

What else should I look at to get rid of this code, or is it just a bug? I haven't had any problems starting or stalling out, although my fuel economy seems a bit low...getting a lot less than 300 miles out of a tank. I thought maybe this would have helped that. I know someone mentioned something about vacuum hoses but I'm not really sure where I should be looking (any pics/diagrams would be helpful). I did check over what I think are the vacuum hoses and none appeared to be cracked or damaged. 

The light seemed to come on soon after I bought the car in June (the guy I bought it from had the A/C compressor replaced..don't know if it's related to anything but i'd thought I would make a mention of it. 

Any help or suggestions would be appreciated!


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## jdg (Aug 27, 2009)

mbz321 said:


> I have a 98 200sx 1.6 L that has been throwing me a P0105 code (pulled at Autozone and manually with the ECU), which shows faulty *map* sensor. So far I have:
> 1.) removed the sensor and sprayed with electric parts cleaner, checked the connectors and they appear okay. Replaced sensor, reset the code. Restarted car, light went away but came back on less than 10 seconds later.
> 2.) I purchased a used *MAF* on ebay, didn't try cleaning it but seller claims it's in working condition. Put that in, reset the code again...and light still came back on!


P0105 = bad *MAP* sensor, not *MAF* sensor. You can _sometimes_ clean a MAF sensor and get it working again. Ya can't really clean a MAP sensor and revive it. Just doesn't work that way...
MAP sensor on my '98 200SX/SE is mounted roughly on top of the intake behind the throttle plates. Yours should be mounted in the same place, might be mounted off the intake with a vacuum line running to it. Check that vacuum line, make sure it isn't cracked or broken or something.
MAF sensor on my 200SXSX/SE is mounted in line with the air intake tube coming from the air cleaner box.
In this type of engine, the MAP isn't used for primary fuel delivery calculations. It's more or less a backup sensor in the case the MAF sensor (primary for fuel delivery) goes to crap. In other words, this engine will run ok without a working MAP sensor, but will obviously throw a code and economy will drop a bit...
<babble>
Generally speaking, if an engine has a MAF sensor, it's primary mode of operation is usually called Mass Air Flow Fuel delivery. If it doesn't have a MAF sensor but has a MAP sensor, like my Dodge pickup, it's primary mode of operation is usually called Speed-Density Fuel delivery, and if the MAP goes to crap, it goes into a 'limp home' mode where it runs like crap, but it runs.
If it's got a MAF and a MAP, it runs Mass Air as primary, Speed-Density as backup if the MAF dies. And if both the MAF and MAP die, then dumps into 'limp home' mode as described above...
</babble>
You can replace the MAF sensor all day, every day, and still not fix a P0105 code.
One way to figure it out, and to satisfy some curiousity... Disconnect the MAP sensor, start the engine drive it around the block. Then reconnect the MAP sensor, and disconnect the MAF sensor. If both are working, the engine should run decent both ways, but will obviously throw a code. If one or the other isn't working right, something will go crap, the engine won't run for crap, the CEL might start blinking. Haven't tried it on either of my B14's, but I think I will this weekend just to see exactly what happens.


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## mbz321 (Aug 14, 2009)

Just googled for this part...doesn't seem to be any used ones available...and new is over $300  I assume this is what I would need: ACDelco MAP Sensor - 1998 NISSAN 200SX 1.6L . There seems to be very little information on google about this part and I can't find anyone selling it used. Does it go by any other names besides map and manifold absulute pressure sensor?I don't remember seeing anything that looks like this under my hood but I'll take a look again tomorrow. 

Another question relating to fuel economy: when I bought this car it came with what looks like an aftermarket gas cap with a vent in it. Is there any way this could be causing a fuel economy issue as well?
thanks for your help.

Edit: doing further research, I found this on ebay NISSAN MAXIMA SENTRA 200SX BOOST MAP SENSOR PS54-01:eBay Motors (item 120480444924 end time Oct-23-09 15:13:34 PDT) . Is this the part I need? I can't tell if there are any differences between this and the new one I linked. So this is the part that says Boost on it towards the top-back of the engine bay?


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## jdg (Aug 27, 2009)

Ya, the PS54-01 is the right one. I'd 'borrow' one from somebody if you could for testing. The same sensor is used in bunch of Nissan products, Sentra, 200SX, Altima, etc.
But before you go and buy it, since you didn't check the right sensor in the first place, I'd go out, pull yours off and see if there's anything obviously wrong with it first, the broken vacuum line (likely), replug the connector (also likely), wiring damage (not very likely I suppose), or maybe you've just got a bad part (really not very likely but could happen).
Give it a good thump up-side-the-head with your hand, put it back in and see what happens.
I work in a shop that fixes _stuff_ (and by _stuff_ I mean exactly that, I get crap in that hasn't been manufactured or supported by their makers in literally decades).
You'd be surprised at how much stuff can be fixed and run good for another 10-20 years, by replugging connectors, whacking them up-side-the-head, kicking them in the right place, replacing a hidden fuse, and so on... I call it a 'magic seismic event'.
And if the eBay thing doesn't pan out, just go to the junk yard and slip one or two in your pocket while you're looking around for 'other stuff'. 

Gas cap - probably wouldn't see much of a difference. If you had the wrong gas cap on it that didn't vent correctly, you likely get a P04xx series code from the ECU also.


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## mbz321 (Aug 14, 2009)

Success! Went out this morning and sprayed MAP connectors with some cleaner..tapped the sensor on the ground a few times, disconnected and reconnected the vacuum hose. Also cleaned another plug (not sure what this goes to but it's on the lefthand side in the very back, kind of covered over by a reddish rubber cover, but it was FULL of grease!) reset the light and it hasn't come back on! Hopefully my fuel economy improves now.
thanks for your help!


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## jdg (Aug 27, 2009)

Can't beat that with a stick....the free fixes that is...
:givebeer:


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## mbz321 (Aug 14, 2009)

jdgrotte said:


> Can't beat that with a stick....the free fixes that is...
> :givebeer:


Actually, the light came back on the next time that I started the car :lame:...I ordered the ebay sensor and hopefully that does the trick.


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## mbz321 (Aug 14, 2009)

Ok, I've done some more troubleshooting but I'm still getting stuck with the check engine light 

I replaced the boost sensor, light stayed off the first time after clearing and starting, but came back on when I started the car a 2nd time. Would this rule out a wiring issue?

Took the vacuum hose off...no leaks or anything as far as I could tell...I even blew threw it and sealed off the other end with my finger to check for air leaks. All the hoses appear to be connected properly if I am following the diagram under the hood properly. Could it be the solenoid (the part that the hose from the MAP connects to)? I don't see anyone selling replacements of this part. 

What else should I be looking for?


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## Faja (Aug 31, 2009)

mbz321 said:


> Could it be the solenoid (the part that the hose from the MAP connects to)? I don't see anyone selling replacements of this part.
> 
> What else should I be looking for?


Yes, that solenoid valve could very well have been the issue from the start, which it looks like now. Excerpt taken from an older thread

_*And many times it's that solenoid valve and not the pressure sensor that's faulty...which is why one should perform the FSM diagnostic procedure to isolate the cause of the P0105 code...unless one prefers to guess.*_


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## mbz321 (Aug 14, 2009)

So would this be the part I need?
Nissan Sentra & Pathfinder '98-'03 Purge Solenoid:eBay Motors (item 270471709793 end time Nov-16-09 15:02:53 PST)

This is the only one I see listed on the internet...unless I am looking up the wrong name/part that I need. I found other valves and solenoids but none which look like anything under my hood.


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## mbz321 (Aug 14, 2009)

Ok, something new I discovered if someone can help...I switched the MAF I replaced back to the original one and noticed something. It appears this vacuum hose with a metal hook-like thing on the end, coming from the transmission? is disconnected from somewhere. I looked over everything but I didn't see any place it would go. The vacuum hose diagram on my hood is hard for me to follow. Is this supposed to be connected to something? (if so, where should I be looking?) I am attaching an image so you can see what I am talking about. 
 
thanks all for your assistance.


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## Faja (Aug 31, 2009)

I'm not sure if that is the exact part but what you are looking for is a MAP/BARO Switch solenoid valve for your model. Maybe call the dealer or print out picture and see if it's the same, they might call it by a different name

Also I think that hose you see is just some sort of ventilation hose so its end is open by default.


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## Jopet (Aug 10, 2009)

faja is right. tht hose does not go anywhere. I think its a vent for the trans to release heat. I think. but for sure the end does not connect to anything. Mine actually hangs on a sort of hook on the air intake


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## jdg (Aug 27, 2009)

Jopet said:


> faja is right. tht hose does not go anywhere. I think its a vent for the trans to release heat. I think. but for sure the end does not connect to anything. Mine actually hangs on a sort of hook on the air intake


Mine too...just hangs out, waiting for something to happen, and it never does...


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## mbz321 (Aug 14, 2009)

OK, figured this would be my last troubleshooting step before I go and try and find a solenoid...

The vacuum line that is coming from the boost sensor, is it supposed to connect to the top or the bottom 'port' on the solenoid? Thanks all again for your assistance.


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## jdg (Aug 27, 2009)

mbz321 said:


> OK, figured this would be my last troubleshooting step before I go and try and find a solenoid...
> 
> The vacuum line that is coming from the boost sensor, is it supposed to connect to the top or the bottom 'port' on the solenoid? Thanks all again for your assistance.


Doesn't one side say VENT and the other side not say VENT?


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## mbz321 (Aug 14, 2009)

jdgrotte said:


> Doesn't one side say VENT and the other side not say VENT?


I'm not sure what you mean side...on the solenoid? I don't remember seeing anything printed on it, but it's pretty hard to see with all the other stuff in the way. What I'm talking about looks like this:


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## mbz321 (Aug 14, 2009)

Ok, I finally tried to fix this using a brand new solenoid from here:
VALVE ASSY-SOLENOID - Sentra / 200SX (B14U) 1995-1999 :: Nissan Parts, NISMO and Nissan Accessories - Courtesyparts.com

Replaced it, and light came right back on ugh. Hopefully this is the correct part that I should have replaced? My only other theory is the boost sensor from ebay I ordered a while back was also defective. If not that, I guess it would be something with the wiring?? I am so frustrated with trying to get the damn light to go away, in hopes it will bring my car better MPG.

And can anyone answer my question above about what vacuum hose goes where so I can rule that out?

thanks


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