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960 Bad ECM???? 900 1994

posted by  DanR on  Sat Mar 30 08:55 CST 2002
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last visit: Thu Oct 23 15:25 CST 2014
[RELATED]

Failed our states emissions test in Dec. just over the limit for HC. Approaching 200k miles everyone figures its the cat. It is the original one so it makes sense. Before the work is done check engine lights up. Pull code 212 O2 signal, cannot reset, figure new O2 sensor while I am at it. Drive it about 2 months before I can get the time to replace everything. All new cat. and O2 sensor, drive it about 10 minutes from cold and check engine light comes back on, codes the same 212. Check all connections and reset. Drive it about 45 minutes before light comes back, 212. Reset code and drive for 2 days before light comes back on. Now it will not reset, always showing 212.

Today with the volvo fault tracing book, checked all connections to the ECM everything checks out with the book, all values are within specs. all voltages are correct. WHAT ARE THE ODDS THAT I INSTALLED A DEFECTIVE 02 SENSOR? or worse is the ECM bad.

And will driving it in the default mode harm my new cat.?

Any and all comments welcome.

DanR 94 964 193k miles
--
DanR








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    960 Bad ECM???? 900 1994

    posted by  someone claiming to be Toyota Tom on  Sat Mar 30 09:49 CST 2002 [RELATED]

    About 70% of the time it is a fault in the GROUND path of the o2 sensor signal. Replacing the sensor helps for a short time.

    Extemely unlikely that your ECM went bad.








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      It's too bad you went to the other side!!! 900 1994

      posted by  DanR on  Sun Mar 31 06:54 CST 2002
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      last visit: Thu Oct 23 15:25 CST 2014
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      You were right again, Oh wise one. Thank you. It turned out that the ground wire near the drivers side motor mount was corroded and loose. I really wanted to add a second ground wire by splicing in another one, but there is no room to work on a splice.

      Not only did that get rid of the check engine light but the idle smoothed out too. Took it out for a beating, it is raining out now, it has been awhile since the rear wheels would spin on wet pavement. Well they spin so much the rear end locks up. Maybe the gas mileage will go back up too.

      Thanks again Tom.
      --
      DanR








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      960 Bad ECM???? 900 1994

      posted by  DanR on  Sat Mar 30 10:49 CST 2002
      Author: [PROFILE] [EVERY POST] [THREADS] [BEST POSTS] RSS Feed     [IGNORE ALL POSTS]
      last visit: Thu Oct 23 15:25 CST 2014
      [RELATED]

      You know it is only with things like this that I am usually in the upper 10%. What you say makes sense. The initial code came on right after a major snow storm and the streets were buried in deep slushy snow with lots of road salt.

      Thanks Tom, I will check it out and report back.

      DanR 94 964 193k miles
      --
      DanR







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