CEL P1400 MDP sensor questions?

Posted by 19BLACKGST98, Jul 5, 2012
Maintenance & Repairs - Oil choices, timing belt, setting timing, CV boot replacement, alternator servicing, fuse/relay checks, and other basic maintenance, repair and diagnosis discussions.

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  1. 19BLACKGST98

    19BLACKGST98 Proven Member McKinney, Texas

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    Ok well I hopped in the car this morning to get it inspected but during warm up this Cel came on (p1400). When I purchased the car it had this cel so I purchased a mdp sensor from the forums and installed it. I thought it fixed the problem because the cel was gone but it may have just been gone because ive been disconnecting the batt since the car has been sitting.

    I pulled the sensor after I got back from the parts store to see if something was blocking the hole in the manifold. It looked fine but I noticed a small tear in the mdp sensors O ring. I figured that Oring may be the issue so I will swap it with the mdp sensor in my gst since it has link.

    My question now is if it turns out that the gst sensor fixes the problem how long will I have to drive the car before it will pass inspection? Will the cel go away on its own? I know if I unhook the battery it will go away but I wont be able to pass inspection for like 50 miles. Also if I unhook the battery will the cell stay off even if it did not fix the problem causing me to wait even longer for inspection?

    All of this is for a stock 97 gsx auto.
    Any help is appreciated.
     
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  2. EAKEREAK

    EAKEREAK Proven Member Las vegas, Nevada

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    Your MDP (Manifold Differential Pressure) Sensor is done. It's not going to effect your drive ability. It's really only there to make sure your EGR valve is working properly (it helps display the readiness code for it) it's just to tell the ECU that the EGR valve is working properly, you'll get a CEL for the sensor being out and your readiness code for the EGR won't show ready. By replacing it it should remove MIL light after driving it for a while
     
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  3. 19BLACKGST98

    19BLACKGST98 Proven Member McKinney, Texas

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    I just replaced it when I purchased the car but its really easy so ill change it again. I was more curious how long ill need to drive it before I can get it inspected after I change it. Someone locally told me around 400miles so I was hoping for a shorter answer or a way to speed up the process.
     
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  4. EAKEREAK

    EAKEREAK Proven Member Las vegas, Nevada

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    I would drive for at least 50 miles highway
     
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  5. 95'RS-T

    95'RS-T Proven Member Germansville, Pennsylvania

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    I'm not sure how Texas emissions works but, with a 98 I'm pretty sure you can have a max of 2 monitors not ready for emissions to pass. As for the CEL here in PA if the light is on, the machine automatically fails the car. The worst thing you can do for readiness monitors is disconnect the battery, because they all reset everytime you do that. Every time the CEL is turned off with a scan tool the monitors are reset as well. Just something to think about before going, and perhaps paying for the test and not passing. Here in PA you pay for the test pass or fail. Get a mdp sensor and have a autozone or advance shut the light off for you and drive like stated about 50 to 75 miles and you should be good. You could also ask them at zone or advance to tell you how many monitors are ready.
     
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  6. 19BLACKGST98

    19BLACKGST98 Proven Member McKinney, Texas

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    Ok ill get on that. Thanks guys.

    Edit: the bad thing about driving it 50 miles is that the car has Alabama plates and its out of state registrations out.
     
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  7. NHerron

    NHerron Proven Member Missoula, Montana

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    Ah ha! I never thought about looking for this before but check it out, the DSM emissions Wiki. Hopefully that gives you more info

    OBDII Emissions Testing and the DSM - DsmWiki

    Also try this, it's easy enough anyway
    http://wiki.answers.com/Q/How_do_you_set_obd2_readiness_monitors

    And this, from http://www.crxsi.com/info/driveability-diagnostics-emissions/OBD2-Diagnostic-Tips.htm
    More confirmation

    http://www.aaapa.org/wp-content/uploads/2010/08/obdii_issues.pdf

    And this is TSB#00-13-005 mentioned in the link above
    http://mitsupartsworld.com/Diamante TSB/tsb0313005.pdf

    Let us know how it turns out for ya!
     
    Last edited by a moderator: Jul 10, 2014
    #7
  8. 19BLACKGST98

    19BLACKGST98 Proven Member McKinney, Texas

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    How have I never seen that wiki before? Before I made the thread I did a search for my specific issue and never ran into it.
     
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  9. EAKEREAK

    EAKEREAK Proven Member Las vegas, Nevada

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    Nice job NHerron that actually helped me out too thanks
     
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  10. NHerron

    NHerron Proven Member Missoula, Montana

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    #10
  11. 19BLACKGST98

    19BLACKGST98 Proven Member McKinney, Texas

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    Does anyone know if the cel will go off after I replace the sensor or do I have to have it reset then drive the car around? Ive currently driven the car about 70 miles since replacing it and still have the cel. Ive only taken it on 2 country road drives during those miles.
     
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  12. NHerron

    NHerron Proven Member Missoula, Montana

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    Code needs to be reset with any cheapo OBD-II scanner
     
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  13. 19BLACKGST98

    19BLACKGST98 Proven Member McKinney, Texas

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    Ok thank you. I read otherwise when I did a google search but it wasnt car specific.

    They wouldnt reset it at the parts store so I disconnected the batt and am 25 miles inyo my 50+ mile cruse.
     
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  14. 19BLACKGST98

    19BLACKGST98 Proven Member McKinney, Texas

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    65 miles and no check engine light. I will drive it to the NTB about 20 miles away for the inspection tomorrow....will have my fingers crossed the whole way.
     
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  15. NHerron

    NHerron Proven Member Missoula, Montana

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    I have this code every 3 starts of the car. It doesn't matter the mileage, as I have driven 300 consecutive miles (very recently, we moved across state) without it coming on. But if I start the car x amount of times it pops up, I'd have to look through the FSM again on this code though, I believe it has to meet a few requirements during each start up (ie drive above 40MPH for at least 60 seconds etc)
     
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