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Home >> Cadillac >> 1996 >> Seville SLS >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - Tests W/Codes >> Diagnostic Trouble Codes >> DTC P0326 - Knock Sensor Circuit Excessive Spark Retard >> Diagnostic Procedures

Diagnostic Procedures

  1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
  2. Start engine. Observe if engine is producing excessive mechanical noise. If excessive noise is observed, go to next step. If excessive noise is not observed, go to step 4).
  3. Locate and repair source of noise.
  4. Use higher octane fuel. If higher octane fuel is not available, go to next step. If higher octane fuel is used, go to step 6).
  5. Using scan tool, select MORE then select SERV. SPARK under MISC. TEST function. Activate SERV. SPARK (this can lower base timing from 10° to 6°BTDC). Retard base timing at 2°BTDC increments as needed. SERV. SPARK will stay at set reading until changed with scan tool or when power to PCM is disconnected.
  6. Fill fuel tank with premium fuel. Drive vehicle for about 15 minutes, allowing PCM to adjust to the premium fuel.
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