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  1. #1
    Join Date
    Oct 2002
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    I have '98 V70 XC that has had a repeated case of the "Check Engine" light coming on.  Th problems first started occurring right after I had brought the car into the local Volvo dealer in Bellevue, WA for the 40,000 mile tune-up about 16 months ago (though that might have been circumstantial).  One day after picking up the car, the "Check Engine" light came on so it was brought back in.  They replaced the charcoal canister and EVAP valve, and reset the light.  About 2 months after that (and 4k miles), the "Check Engine" light came on again.  When brought into the dealer, they were unable to find anything and reset the light (they did warn me about being sure to check that the gas cap was tight, and not to try to add any additional gas after the pump shut off).  About 4 months after that episode (and another 5k miles), the "Check Engine" light once again came back on, so it was another trip to the dealer.  They again replaced the charcoal canister and EVAP valve, and reset the light.

    Here it is another 9 months later (and about 11k miles) and the dang "Check Engine" light has come on again.  The car is now out of warranty, and I wanted to try and sort out the problem for myself. I hooked up my OBDII code reader and got a code P0108. According to the manual which came with my reader this code is for "Manifold Absolute Pressure/Barometric Pressure Circuit High Input".  Can anyone out there help me interpret what the problem might be, and how to correct it? I haven't been able to sort out a solution from the Haynes manual for the car.  This continual problem is wearing a bit thin, and has me wondering if I should hang onto this car.

  2. #2
    Art's Avatar
    Art is offline Senior Member & VolvoXC.com Supporter
    Join Date
    Oct 2001
    Location
    Red Deer, AB., Canada
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    4,120

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    Hmm...wonder if it's a malfunctioning sensor as explained in this
    post?

  3. #3
    Join Date
    Oct 2002
    Posts
    5

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    I'll try to take a look at the sensor this weekend, and place a post if it was the problem.

    If anyone else has any other ideas, I'd like to hear from you as well.

    Thanks.

  4. #4
    Join Date
    Oct 2002
    Location
    Southern Ontario
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    125

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    Does this happen shortly after a fill up?
    11 Flamenco Red T6 w/Espresso interior. Replaced 08 Ruby Red w/Esspresso interior. Replaced 04 Ruby red w/wing and full tint. Replaced 02 Ruby Red.
    Wife's car; 12 XC60 T6 White replaced 05 Ruby Red XC70 replaced 99 V70XC Sandstone

  5. #5
    Join Date
    Oct 2002
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    5

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    It was asked if the problem occured after a fill-up.  The "Check Engine" light (with Code P0180) occured about 150 miles after a fill-up.  Still baffled on the problem.

  6. #6
    Join Date
    Oct 2002
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    5

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    After running through diagnostic testing linked to the barometric pressure sensor (there seemed to be a slight resistance through the unit when there theoretically should have been none), the check engine light went off, and stayed off for about a week-and-a-half, about 300 miles.  Light is now back on.  Will try to find a barometric pressure sensor at a local dealer and replace the unit.  Will post results.

  7. #7
    Join Date
    Oct 2002
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    5

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    The atmospheric pressure sensor was $180 from the dealer, and I bought one.  Before putting it on though, I wanted to do a bit more testing to see if that was truly the problem.  Following is a synopsis of what I've tried.  Any help folks can provide would be appreciated.

    As noted earlier, when I pull the code off using my OBDII code reader, I get a code P0180.  According to alldata.com, this is related to the Volvo code for the Atmospheric Pressure Sensor Signal.  The first thing that is suggested on alldata.com is to pull the connector from the atmospheric pressure sensor, and then to connect an ohmeter between the middle pressure connector location and ground.  The reading should be 0 ohms.  When I do this, I do get pick up a reading.  

    They then suggest to "Check ECM connector for contact resistance and oxidation and remedy".  Not being too sure what they are really after, I've pulled the ECM unit out to look for corriosion, and found none on either the ECM male pins, or onthe ECM connector's female pins.  I still sprayed the ECM connectors female pins with CRC electrical cleaner, let dry, and plugged everything back together.  When I checked with the ohmmeter, I still had resistance between the atmospheric connector pin #2 and ground.

    The next step they suggested was to "check cable between atmospheric pressure sensor terminal 2 and ECM #B28 for an open circuit". Near as I can tell, #B28 is a ground circuit for the tank pressure sensor, the A/C pressure sensor, and the accelerometer.  Thinking that maybe one of these three units might be faulty, I unplugged each (I'm assuming the accelerometer is the unit mounted on the cross-frame piece immeaditely behind the radiator), and checked again for resistance on the atmospheric sensor terminal 2.  I still have resistance.  When I unplug the ECM unit, the resistance goes away.

    Does anyone have any bright ideas as to where I should go next??

  8. #8
    Join Date
    Nov 2002
    Location
    SE WI
    Posts
    1,306

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    Unfortuneatly, you can't pull the plug on the bulb lighting the dreaded "CHECK ENGINE LIGHT" Emissions inspection now plug into the OBD. -Dick
    '11 XC70 Silver/Off Black-Hers
    '03 XC70 Silver/Charcoal-His
    '99 XC70 Silver/Charcoal -Granddaughter's
    '87 740GLE Junk [email protected] miles
    2013 Porsche Boxster
    2017 Porsche C4S

  9. #9
    Join Date
    Dec 2002
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    1

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    I purchased a 98' volvo XC this summer and have had the check engine light come on three times in 6 months.  Its driving me totally insane.  The firest thing my mechanic fixed was a secondary airpump  $500.00 later I passed my emmissions test.  Thats good!  three-hundred miles later, its on again.  Went back in $120.00 later its supposedly fixed.  Another 300 miles on again!  By this time my husband is ready to drive the car off a cliff!.  Its in the shop more time than on the road.. The third time, my mechanic tells me the computer hooked up to emissions system needs replacing and it will cost.  $1,100.00 to fix.. Could they have figured this out three months ago... By now, I don't beilieve him.. I'll pick -up the car and hopefully get rid of it engine light on or not.  Its been a complete nightmare.  Interestingly though, I have a 13 year olf 740 sedan that has 204,000 miles on it and just keeps going and going.  THATS the car I drive to work everyday! not the wagon...  I'm ready for a Toyota SUV, and I don't care if it drinks gas or not, at least it will be in my garage and  not in the shop..

  10. #10
    Join Date
    Feb 2003
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    1

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    My check engine light also comes on all the time.  The code is P455 Evaporative Emissions Control System Leak Detected (gross leak)  They have replace the gas cap, the sensor and the control valve itself.  Each time the check engine light came on after about a 2 weeks.  I bought an OBD reader and have saved a fortune in diagnostic costs.  It seems the light goes on when the car is idleling after in traffic after comming off the interstate.  No one seems to know  why it turns on including me.  The dealer did say it will not effect performance and I had the emissions tested and passed but the check engine light drives be crazy

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