LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Mazda >> 2006 >> MX-5 Miata Base >> Repair and Diagnosis >> Engine Performance >> System >> On-Board Diagnostic [Engine Control System] >> DTC P0012 >> Diagnostic Procedure
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Diagnostic Procedure

DTC P0012 DIAGNOSTIC PROCEDURE TABLE

STEP INSPECTION ACTION
1 VERIFY FREEZE FRAME DATA HAS BEEN RECORDED 
  • Has FREEZE FRAME DATA been recorded?
Yes Go to the next step.
No Record the FREEZE FRAME DATA on the repair order, then go to the next step.
2 VERIFY RELATED REPAIR INFORMATION AVAILABILITY 
  • Verify related Service Bulletins and/or on-line repair information availability.
  • Is any related repair information available?
Yes Perform repair or diagnosis according to the available repair information.
  • If the vehicle is not repaired, go to the next step.
No Go to the next step.
3 VERIFY RELATED PENDING CODE OR STORED DTCS 
  • Is DTC P2088 or P2089 present?
Yes Go to the appropriate DTC troubleshooting procedure.
(See DTC P2088  or DTC P2089  .)
No Go to the next step.
4 VERIFY ENGINE OIL PRESSURE 
  • Start the engine.
  • Does the oil pressure warning light illuminate?
Yes Inspect the engine oil pressure, then go to Step 8.
(See OIL PRESSURE INSPECTION .)
No Go to the next step.
5 VERIFY TIMING CHAIN INSTALLATION  Yes Go to the next step.
No Reinstall the timing chain, then go to Step 8.
6 INSPECT OCV FOR MALFUNCTION 
  • Stop the engine.
  • Remove the OCV.
  • Inspect the position of the spool valve in the OCV.
  • Is the spool valve located at the valve retard position?
Yes VARIABLE VALVE TIMING MECHANISM IS NORMAL 
NOTE:
  • This DTC is detected as an intermittent concern.
  • An intermittent concern might be removed using the cleaning mode of the variable valve timing control function.

Go to the next step.
No Replace the OCV, then go to Step 8.
(See OIL CONTROL VALVE (OCV) REMOVAL/INSTALLATION .)
7 INSPECT ENGINE OIL RUNNER 
  • Inspect the following engine oil runners for clogging or leakage.
    • Between oil pressure switch and OCV
    • Between OCV and variable valve timing actuator
    • In variable valve timing actuator
  • Is there any clogging or leakage?
Yes Repair or replace the suspected runner, then go to the next step.
No VARIABLE VALVE TIMING MECHANISM IS NORMAL 
NOTE:
  • This DTC is detected by intermittent concern.
  • An intermittent concern might be removed using the cleaning mode of the variable valve timing control function.

Go to the next step.
8 VERIFY TROUBLESHOOTING OF DTC P0012 COMPLETED 
  • Make sure to reconnect all disconnected connectors.
  • Clear the DTC from the PCM memory using the WDS or equivalent.
  • Turn the ignition switch off.
  • Start the engine and warm it up completely.
  • Is the PENDING CODE for this DTC present?
Yes Replace the PCM, then go to the next step.
(See PCM REMOVAL/INSTALLATION .)
No Go to the next step.
9 VERIFY AFTER REPAIR PROCEDURE  Yes Go to the applicable DTC inspection.
(See DTC TABLE  .)
No Troubleshooting completed.