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Check engine light - 1995 850 (long) 850

posted by  pgao on  Sat Mar 29 12:34 CST 2008
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last visit: Fri Dec 27 08:18 CST 2013
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All,

A couple of days ago, the check engine light turned on on my 1995 850 that has a little over 130K miles on it. The code pulled from the A2 is 1-2-3. From what has happened in the recent days, the check engine light definitely has something to do with the Coolant temperature sensor. I am posting a message here to make sure I will take care all the problems.

Here is the story:
1. Just before the light went on, I noticed there's a surge in rpm, from normal 800 to about 1200.
2. The temperature gauge acting erratically, moving between the 3 o'clock position and the 5 O'clock position (the lowest point the needle can go.)
3. Sometimes, it took a little effort to start the car and the car was running rough at the start (seemed not all cylinders were firing). It would be Ok after a couple of minutes. Temperature here in NY is about 40F during the day.
4. Every time when the temperature gauge's acting, there's a surge in rpm.
5. Seems that the car lost some coolant; but there is no obvious leak.
6. I cleared the code this morning. After several rounds of driving, it came back on. After stopping for traffic lights, I felt the hesitation when I tried to resume driving. Again, the hesitations were accompanied by the temperature "drop" (by the temperature gauge).
7. Another wired thing is that the fan kept running for a few minutes after the car's keyed off. It never happened before.

About a couple months ago, the car was overheating for a few minutes (on Highway) due to a big leak in the radiator. the radiator, tubes, and tank were replaced afterwards. Since the thermostat (volvo) was pretty much new, it was not replaced; neither was the temperature sensor.

So, my question is: besides to get the sensor (and thermostat) replaced, what else should I also check?

Thank you in advance for your inputs.

I apologize for this long posting.

Paul







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    Check engine light - 1995 850 (long) 850

    posted by  pgao on  Sun Apr 6 15:39 CST 2008
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    last visit: Fri Dec 27 08:18 CST 2013
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    Just a note.

    It seemed that replacing the ECT sensor has solved the problem. The check engine light has not come back on for several days.

    Today, I replaced cabin filter, air filter, and spark plugs. To my surprise, one of the spark plugs was wet (soaked with gas) (the first one on the driver side). There definitely was misfire in the cylinder. So, the question is: Can the new spark plug solves the problem or something else is going on? Your wisdom is needed.

    Thanks much.
    Paul








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    Check engine light - 1995 850 (long) 850

    posted by  pgao on  Sat Mar 29 12:41 CST 2008
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    last visit: Fri Dec 27 08:18 CST 2013
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    Another note. Just when the code's reset, there's (a sound of) of the release of pressure. I didn't catch the location of the sound. but it definitely came from the location where the thermostat locates.

    Thanks,








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      Check engine light - 1995 850 (long) 850

      posted by  KlausC on  Sat Mar 29 13:26 CST 2008
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      last visit: Fri Oct 24 10:15 CST 2014
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      Because they are in the same area, I would replace the temp sensor and the thermostat. Make sure they are OEM and not some knock off.
      Remember to drain about a quart of antifreeze from the bottom of the engine block, you don't want antifreeze pouring all over your alternator.
      Those T40 screws that hold down the thermostat housing are a real pain. If they are "new" from the last time, fine, but if they are original to the car, buy 2 new ones. You will probably mess one of them up.

      Your story of stumbling is correct, because when the ECT thinks the engine temp is low, more fuel gets injected into the cylinders and missing will occure.

      Klaus
      --
      The 164 has a new home, all I am left with are a 95 854T and a 98 V70R :)







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