GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 2009 🢒 Lucerne 🢒 Engine 🢒 Engine Controls and Fuel - 4.6L 🢒 DTC P0315

Diagnostic Instructions
    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    •  Diagnostic Procedure Instructions provide an overview of each diagnostic category.

DTC Descriptor

DTC P0315: Crankshaft Position (CKP) System Variation Not Learned

Circuit/System Description

The crankshaft position (CKP) system variation learn feature is used to calculate reference period errors caused by slight tolerance variations in the crankshaft, and the CKP sensor. The calculated error allows the engine control module (ECM) to accurately compensate for reference period variations. This enhances the ability of the ECM to detect misfire events over a wider range of engine speed and load.

The CKP system variation compensating values are stored in ECM memory after a learn procedure has been performed and the ignition switch is turned to the OFF position for at least 30 seconds. If the actual CKP variation is not within the CKP system variation compensating values stored in the ECM, DTC P0300 may set.

If the CKP system variation values are not stored in the ECM memory or a proper ECM power down does not occur after completing the CKP Learn Procedure, DTC P0315 sets.

Conditions for Running the DTC

The diagnostic runs continuously.

Conditions for Setting the DTC

The ECM detects that the CKP system variation values are not stored in memory.

Action Taken When the DTC Sets

DTC P0315 is a Type A DTC.

Conditions for Clearing the MIL/DTC

DTC P0315 is a Type A DTC.

Conditions for Clearing the MIL/DTC
    • The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
    • A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
    • A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
    • Clear the MIL and the DTC with a scan tool.

Reference Information

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Testing

Important: The CKP System Variation Learn Procedure may have to be repeated up to 5 times before the procedure is learned.

  1. Perform the Crankshaft Position System Variation Learn . The scan tool should display Learned this Ignition.
  2. If the CKP System Variation Learn Procedure cannot be performed successfully, inspect for the following conditions:
    3. • Any worn crankshaft main bearings.
    • A damaged or misaligned reluctor wheel.
    • Excessive crankshaft runout.
    • A damaged crankshaft--Refer to Crankshaft and Bearing Cleaning and Inspection .
    • Interference in the signal circuit of the CKP sensor.
    • The ignition switch is in the ON position until there is insufficient system voltage.
    • An ECM power disconnect with the ignition ON that may have erased the CKP system variation values and set DTC P0315.
    • Any debris between the CKP sensor and the reluctor wheel
    ⇒If the control module is unable to complete the learn procedure, replace the control module.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for ECM replacement, setup, and programming