53 Knock Sensor Circuit - Knock Present

From SaturnWiki
Jump to: navigation, search


The purpose of this flag is to indicate excessive engine noise. The knock sensor cannot differentiate between spark knock and other engine noise. When the knock sensor cannot eliminate noise by retarding timing, Flag 53 will be set.

Information Flag Parameters

Information Flag 53 will set if:

  • If the PCM cannot reduce engine noise by retarding timing (i.e. the engine noise is most likely not due to spark knock).

Diagnostic Aids

Information Flag 53 indicates excessive engine noise usually caused by something else besides spark knock. It does not indicate a faulty ESC subsystem.


   * Valve lifter noise
   * Belt tensioner
   * Loose bracket
   * Low octane fuel in high ambients while pulling loads
   * Piston/Cylinder bore scuffed

NOTICE: Information flags should be used for diagnostic purposes only. They do not necessarily indicate component malfunction/failure.

  • The PCM has the ability to learn spark retard. If knock is present long enough to fill the mid, hi and low spark compensating cells a low power condition may result due to maximum spark retard. The spark compensating cells will eventually learn back (0) when knock condition is corrected, however, this is a slow process. The spark compensating cells may be quickly cleared by disconnecting the power to the PCM when the knock condition has been corrected.