1991 Subaru Legacy non-turbo indicates knock sensor trouble code

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 knock?

I appreciate any ideas anyone might have....

-V

Reply to
vhauri
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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

Reply to
Carl 1 Lucky Texan

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.

Reply to
johninKY

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).

-Vasken

Reply to
vhauri

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