DTC P0326 Knock Sensor CKT Excessive Spark Retard. Cadillac Concours 1997

For 1990-2009 cars
Engine Controls Components
Ignition Control (IC) Module
OBD II Symbol Description Notice
ESD Notice

### Circuit Description

This DTC will set if the knock system is otherwise functioning normally but is detecting excessive knock. This may be due to a noisy engine producing excessive mechanical vibrations from piston slap, valve closures, etc. Excessive knock could also be produced by very low octane fuel (85 octane or less).

### Conditions for Setting the DTC

#### Test Conditions

• | DTC(s) P0325 and P0327 not set.

• | Ignition voltage at least 10 volts.

• | Knock Learn is enabled.

• | Octane learn /lock-in not complete.

#### Failure Condition

The 87 octane Decay Multiplier is 0.996 or more for 64 seconds.

### Action Taken When the DTC Sets

• | The Malfunction Indicator Lamp (MIL) will not illuminate.

• | No message will be displayed.

### Conditions for Clearing the DTC

• | A History DTC will clear after forty consecutive warm-up cycles with no failures of any non-emission related diagnostic test.

• | A Last Test Failed (current) DTC will clear when the diagnostic runs and does not fail.

• | Use a scan tool to clear DTCs.

• | Interrupting PCM battery voltage may or may not clear DTCs. This practice is not recommended. Refer to Clearing Diagnostic Trouble Codes in PCM Description and Operation.

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | Go to Step 2 | Go to A Powertrain On Board Diagnostic (OBD) System Check
2 | Start the engine. Does engine produce excessive mechanical noise? | -- | Go to Step 3 | Go to Step 4
3 | Locate and repair source of noise. Is the repair complete? | -- | Go to Powertrain Control Module Diagnosis for Verify Repair | --
4 | Inform owner that the use of premium fuel is required for optimum vehicle performance. Is premium fuel unavailable or does customer decide not to use premium fuel? | -- | Go to Step 5 | Go to Step 6

5

1. Using a scan tool.
2. Select Serv. Spark.
3. Activate Serv. Spark (this can lower base timing from 10° BTDC to 6° BTDC).
4. Adjust base timing amount of degrees needed, start at 2 degrees increase as needed.

Serv. Spark will stay at set reading until changed with a scan tool or vehicle power to the PCM is disconnected.

Is the repair complete?

--

Go to Powertrain Control Module Diagnosis for Verify Repair

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6

1. Fill fuel tank with premium fuel.
2. After approximately 15 minutes of driving the PCM will have adjusted to the premium fuel.

Is the repair complete?

--

Go to Powertrain Control Module Diagnosis for Verify Repair

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