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Home >> Mazda >> 2006 >> MX-5 Miata Base >> Repair and Diagnosis >> Engine Performance >> System >> On-Board Diagnostic [Engine Control System] >> DTC P0118 >> Diagnostic Procedure
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Diagnostic Procedure

DTC P0118 DIAGNOSTIC PROCEDURE TABLE

STEP INSPECTION ACTION
1 VERIFY FREEZE FRAME DATA AND DIAGNOSTIC MONITORING TEST RESULTS HAVE BEEN RECORDED. 
  • Have FREEZE FRAME DATA and DIAGNOSTIC MONITORING TEST RESULTS (Engine cooling system related) been recorded?
 Yes Go to the next step.
No Record the FREEZE FRAME DATA and DIAGNOSTIC MONITORING TEST RESULTS 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 INSPECT POOR CONNECTION OF ECT SENSOR CONNECTOR 
  • Turn the ignition switch off.
  • Disconnect ECT sensor connector.
  • Inspect for poor connection (such as damaged/pulled-out pins, corrosion).
  • Is there any malfunction?
 Yes Repair or replace the terminal, then go to Step 9.
No Go to the next step.
4 CLASSIFY ECT SENSOR MALFUNCTION OR WIRING HARNESS MALFUNCTION 
  • Connect the WDS or equivalent to the DLC-2.
  • Access ECT PID.
  • Connect a jumper wire between ECT sensor terminals A and B.
  • Verify the ECT value.
  • Is the voltage 4.58 V or below  ?
 Yes Replace the ECT sensor, then go to Step 9.
(See ENGINE COOLANT TEMPERATURE (ECT) SENSOR REMOVAL/INSTALLATION .)
No Go to the next step.
5 INSPECT ECT SENSOR SIGNAL CIRCUIT FOR SHORT TO POWER SUPPLY 
  • Turn the ignition switch to the ON position (Engine off).
  • Measure the voltage between ECT sensor terminal A (wiring harness-side) and body ground.
  • Is the voltage B+  ?
 Yes Repair or replace the wiring harness for short to power supply, then go to Step 9.
No Go to the next step.
6 INSPECT PCM CONNECTOR FOR POOR CONNECTION 
  • Disconnect the PCM connector.
  • Inspect for poor connection (such as damaged/pulled-out pins, corrosion).
  • Is there any malfunction?
 Yes Repair or replace the terminal, then go to Step 9.
No Go to the next step.
7 INSPECT ECT SENSOR SIGNAL CIRCUIT FOR OPEN CIRCUIT 
  • Inspect the continuity between ECT sensor terminal A (wiring harness-side) and PCM terminal 2AH.
  • Is there continuity?
 Yes Go to the next step.
No Repair or replace the wiring harness for open circuit, then go to Step 9.
8 INSPECT ECT SENSOR GROUND CIRCUIT FOR OPEN CIRCUIT 
  • Inspect for continuity between ECT sensor terminal B (wiring harness-side) and PCM terminal 2AY.
  • Is there continuity?
 Yes Go to the next step.
No Repair or replace the wiring harness for open circuit, then go to the next step.
9 VERIFY TROUBLESHOOTING OF DTC P0118 COMPLETED 
  • Make sure to reconnect all disconnected connectors.
  • Clear the DTC from the PCM memory using the WDS or equivalent.
  • Start the engine, or perform the KOEO self-test with WDS or equivalent.

    (See KOEO/KOER SELF TEST  .)

  • Is the same DTC present?
 Yes Replace the PCM, then go to the next step.
(See PCM REMOVAL/INSTALLATION .)
No Go to the next step.
10 VERIFY AFTER REPAIR PROCEDURE  Yes Go to the applicable DTC troubleshooting.
(See DTC TABLE  .)
No Troubleshooting completed.
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