Will a bad knock sensor keep my subaru from starting

You replaced the knock sensor and not the fuel pump?? Change the fuel pump.

no. you need a new knock sensor.

Hi Lee,
I'm not sure if the programming in that particular vehicle will disable traction control and/or cause the cruise control light to flash because of a faulty knock sensor. There is no way for a repair technician to know all the factors behind the software in your system. You MAY have separate problems with the cruise - then maybe not.

The only thing I can tell you for sure is that Subaru knock sensors are prone to failure due to cracking. The outer shell gets cracks in it and then moisture gets in and corrodes the field windings inside the sensor shorting them out. (SEE PICTURE)

"Reflashing" your computer or resetting the codes will not work if this is the case. You will have to replace the knock sensor FIRST, then reset the computer memory.

before you start taking stuff apart, make sure that the knock sensor is bad and not the wires. test for ground and continuity on the signal wire from the sensor connector to the pin on the pcm connector. google "testing knock sensor" for more info

CODE PO420 CATALYST SYSTEM EFFICIENCY BELOW THRESHOLD BANK I * CODE PO325 KNOCK SENSOR NO.1 CIRCUIT MALFUNCTION BANK NO.1 OR SINGLE SENSOR

the knock sensor itself can be faulty if there is a code showing for it.

CEL lights only come on if a sensor fails its diagnostic, it is nothing to do with the particular sensors readings, but telling you the sensor itself is bad.

The knock sensor is a little microphone attached directly to the cylinder block side wall.

When facing the engine it is in the rear right hand side.

The knock sensor is a piezo electric crystal, when they go bad the must be replaced.

Looks similar to these

it sounds like you have a bad coolant temp sensor

Check wiring if all good than bad sensor

As far as there being no knock sensor on a 99 2.2 I beg to differ. I have a 99 legacy and just had a diagnostic done and mine is bad. If there is no knock sensor why would it say it was bad and why does Auto Zone, Advanced Auto and my local Subaru dealer sell them. Mine is located under the throttel body and they are rather hard to get to. No offence to who ever said ther is no knock sensor but maby you should recheck your information becuse I know there is a knock sensor since I just changed mine.