Diagnostic Procedure

WARNING: This page is about a different car, the 2003 Mazda 6. However, it is still accessible from the selected car via links, so may be relevant.

If FREEZE FRAME DATA has been recorded, go to next step. If FREEZE FRAME DATA has not been recorded, record FREEZE FRAME DATA. Go to next step.
Verify Related Repair Information Availability - Check for related Service Bulletins and/or on-line repair information availability. If any related repair information is available, perform repair or diagnosis according to available repair information. If vehicle is not repaired, go to next step. If related repair information is not available, go to next step.
Inspect ECT Sensor Connector For Poor Connection - Turn ignition off. Disconnect ECT sensor harness connector. Check for poor connection (such as damaged, pulled-out pins, and corrosion). If no malfunction is present, go to next step. If any malfunction is present, repair or replace terminals. After repair, go to step 8.
Inspect ECT Sensor Signal Circuit For Short To Power - Turn ignition on, engine off. Measure voltage between ECT sensor harness connector terminal "A" (White/Blue wire) and body ground. See Figure. If battery voltage is not present, go to next step. If battery voltage is present, repair short circuit to power in appropriate wire between ECT sensor harness connector terminal "A" (White/Blue wire) and PCM 104-pin harness connector terminal No. 38 (Light Green/Black wire) or replace wire harness. See ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL. After repair, go to step 8.
Inspect ECT Sensor - Inspect ECT sensor. Refer to ENGINE COOLANT TEMPERATURE SENSOR under ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING - MAZDA6, MIATA, MPV, PROTEGE & PROTEGE5 article. If ECT sensor is okay, go to next step. If ECT sensor is faulty, replace ECT sensor. After repair, go to step 8.
Inspect PCM Connector For Poor Connection - Turn ignition off. Disconnect PCM 104-pin harness connector. Check for poor connection (such as damaged, pulled-out pins, and corrosion). If no malfunction is present, go to next step. If any malfunction is present, repair or replace terminal. After repair, go to next step.
Inspect ECT Sensor Circuit For Open Circuit - Turn ignition off. Check for continuity between following circuits:
- ECT sensor harness connector terminal "A" (White/Blue wire) and PCM 104-pin harness connector terminal No. 38 (Light Green/Black wire)
- ECT sensor harness connector terminal "B" (Brown/Green wire) and PCM 104-pin harness connector terminal No. 91 (Brown wire)
See Figure. If continuity is present, go to next step. If continuity is not present, repair open circuit in appropriate wire between ECT sensor 2-pin harness connector and PCM 104-pin harness connector or replace wire harness. See ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL. After repair, go to next step.
Verify Trouble Shooting Of DTC P0118 Is Completed - Make sure to reconnect all disconnected connectors. Clear DTC from PCM memory using WDS or equivalent. See CLEARING DIAGNOSTIC TROUBLE CODES under SELF-DIAGNOSTIC SYSTEM. Turn ignition on, engine off. If same DTC is not present, go to next step. If same DTC is present, replace PCM. For PCM removal and installation, see POWERTRAIN CONTROL MODULE under COMPUTERIZED ENGINE CONTROLS in REMOVAL & INSTALLATION article. After repair, go to next step.
Verify After Repair Procedure - Using scan tool, perform After Repair Procedure. See AFTER REPAIR PROCEDURE . If any DTCs are present, go to appropriate DTC inspection. Refer to DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no DTCs are present, trouble shooting is complete.