Knock Sensor on a 2005 Chevy Cobalt?
LisaClark47 asked:
First of all, my husband and I are receiving conflicting information. Is a knock sensor a TYPE of oxygen sensor, a separate part having nothing to do with the oxygen sensor or are they one and the same? The reason I ask, is because whenever I key in the term “Chevy Cobalt knock sensor” on any search engine, I am coming up with several responses pertaining to an oxygen sensor, as well as those that refer to a knock sensor. I would appreciate it, if someone could help by clearing that issue up for me!
Secondly, since the knock sensor needs to be repaired on our 2005 Chevy Cobalt, we need to know if it can be accessed from it’s location in the engine by anyone other than a mechanic who works at a dealership? My husband would like to fix it himself. We have purchased the part, but were “informed” by the place where the diagnostic was done, that it needs to be installed at the dealership. This we believe is only a tactic to get us to dish out more moola to have it done!
First of all, my husband and I are receiving conflicting information. Is a knock sensor a TYPE of oxygen sensor, a separate part having nothing to do with the oxygen sensor or are they one and the same? The reason I ask, is because whenever I key in the term “Chevy Cobalt knock sensor” on any search engine, I am coming up with several responses pertaining to an oxygen sensor, as well as those that refer to a knock sensor. I would appreciate it, if someone could help by clearing that issue up for me!
Secondly, since the knock sensor needs to be repaired on our 2005 Chevy Cobalt, we need to know if it can be accessed from it’s location in the engine by anyone other than a mechanic who works at a dealership? My husband would like to fix it himself. We have purchased the part, but were “informed” by the place where the diagnostic was done, that it needs to be installed at the dealership. This we believe is only a tactic to get us to dish out more moola to have it done!
this one goes directly into the block. i would let a professional deal with anything that goes directly into the block
to give you some insight, the dealer lists the part for $34.37 and only charges .9 of an hour to install on the 2.0L engine
and for the 2.2L engine almost exactly identical
this is straight off of a labor guide used nationwide by mostly all dealerships.
Not related to the O2 sensor. Located on the front of the engine just above the starter KNOCK SENSOR (KS) SYSTEM DESCRIPTION
PURPOSE
The knock sensor (KS) system enables the engine control module (ECM) to control the ignition timing for the best possible performance while protecting the engine from potentially damaging levels of detonation. The ECM uses the KS system to test for abnormal engine noise that may indicate detonation, also known as spark knock.
SENSOR DESCRIPTION
The knock sensor (KS) system uses a flat response 2-wire sensor. The sensor uses piezo-electric crystal technology that produces an AC voltage signal of varying amplitude and frequency based on the engine vibration, or noise, level. The amplitude and frequency are dependant upon the level of knock that the KS detects. The engine control module (ECM) receives the KS signal through a signal circuit. The KS ground is supplied by the ECM through a low reference circuit.
The ECM learns a minimum noise level, or background noise, at idle from the KS and uses calibrated values for the rest of the RPM range. The ECM uses the minimum noise level to calculate a noise channel. A normal KS signal will ride within the noise channel. As engine speed and load change, the noise channel upper and lower parameters will change to accommodate the KS signal, keeping the signal within the channel. In order to determine which cylinders are knocking, the ECM only uses KS signal information when each cylinder is near top dead center (TDC) of the firing stroke. If knock is present, the signal will range outside of the noise channel.
If the ECM has determined that knock is present, it will retard the ignition timing to attempt to eliminate the knock. The ECM will always try to work back to a zero compensation level, or no spark retard. An abnormal KS signal will stay outside of the noise channel or will not be present. KS diagnostics are calibrated to detect faults with the KS circuitry inside the ECM, the KS wiring, the KS voltage output, or constant noise from an outside influence such as a loose/damaged component or excessive engine mechanical noise.