1991 Subaru Legacy non-turbo indicates knock sensor trouble code

Discussion in 'Subaru Legacy' started by vhauri, Jul 17, 2006.

  1. vhauri

    vhauri Guest

    I have a 1991 Legacy sedan with around 116,000 miles on it, and the
    check engine light recently came on. After hooking up the test
    connector, I was able to make the light flash DTC 22 at me, indicating,
    according to the repair manual, a problem with the knock sensor that
    could result in the car defaulting to 'fail-safe' timing mode. Now, it
    seems pretty clear that the first step would be to replace the knock
    sensor, but I don't really have time to do that this week, and it would
    be nice to keep the car in service for short trips to the store, etc.
    So, my question here is a three-parter:
    1) Is there anything I should try before yanking the knock sensor?
    2) Is it safe to drive?
    3) This can't be an indication of engine knock, right? Or would this
    trouble code also manifest because of the beginnings of an engine

    I appreciate any ideas anyone might have....

    vhauri, Jul 17, 2006
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  2. I THINK you may only suffer decreased performance and MAYBE also
    slightly worse fuel economy. If you clear the code by disconnecting the
    neg. term. of the batt., step on the brake pedal, wait for - say -
    20-30, reconnect; and the code immediately is set again - yeah, it's
    likely a real code for a bad knock sensor. If it doesn't come back, it
    could've been some kind of fluke I guess. Do check for corroded ground
    and wiring/connector problems in case re-seating a connector or
    something fixes it.

    Carl 1 Lucky Texan, Jul 17, 2006
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  3. vhauri

    johninKY Guest

    Carl is correct. Clear the code. Remove sensor and check for corrosion.
    If the code returns then replace the sensor. No problem driving it until
    repaired. The ECU will just retard the timing enough that you don't have
    a knock condition.
    johninKY, Jul 17, 2006
  4. vhauri

    vhauri Guest

    Wow, thanks for the quick replies! I noticed the bulletin for this car
    about potentially corroded wires on the knock sensor, so your advice
    about cleaning it off first sounds like a good idea (and cheaper than a
    new sensor, which I like alot).

    vhauri, Jul 17, 2006
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