Diagnostic procedure

WARNING: This page is about a different car, the 2005 Mazda MX-5 Miata. However, it is still accessible from the selected car via links, so may be relevant.

DTC P0118 [BP, BP WITH TC] DIAGNOSTIC PROCEDURE

STEP	INSPECTION		ACTION
1	VERIFY FREEZE FRAME DATA HAS BEEN RECORDED Has FREEZE FRAME DATA been recorded?	Yes	Go to the next step.
1		No	Record FREEZE FRAME DATA on repair order, then go to the next step.
2	VERIFY RELATED REPAIR INFORMATION AVAILABILITY Check for related Service Bulletins and/or online 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.
2		No	Go to the next step.
3	INSPECT ECT SENSOR CONNECTOR FOR POOR CONNECTION Turn the ignition switch off. Remove ACL box. Disconnect ECT sensor connector. Check for poor connection (damaged, pulled-out pins, corrosion, etc.). Is there any malfunction?	Yes	Repair or replace the terminal, then go to Step 9.
3		No	Go to the next step.
4	DETERMINE IF ECT SENSOR MALFUNCTION OR HARNESS MALFUNCTION Measure resistance between ECT sensor terminals A and B (part-side). Is the resistance within 2.27-2.74 kilohms [20°C {68°F}] ?	Yes	Go to the next step.
4		No	Replace ECT sensor, then go to Step 9.
5	INSPECT ECT SENSOR SIGNAL CIRCUIT FOR SHORT TO POWER Turn ignition key to ON (Engine off). Measure voltage between ECT sensor terminal A (harness-side) and body GND. Is voltage B+ ?	Yes	Repair or replace harness for short to power, then go to Step 9.
5		No	Go to the next step.
6	INSPECT PCM CONNECTOR FOR POOR CONNECTION Disconnect PCM connector. Check for poor connection at terminal 4P and 4O (damaged, pulled-out pins, corrosion, etc.). Is there any malfunction?	Yes	Repair or replace the terminal, then go to Step 9.
6		No	Go to the next step.
7	INSPECT ECT SENSOR SIGNAL CIRCUIT FOR OPEN CIRCUIT Disconnect PCM connector. Check continuity between ECT sensor terminal A (harness-side) and PCM terminal 4P (harness-side). Is there continuity?	Yes	Go to the next step.
7		No	Repair or replace harness for open circuit, then go to Step 9.
8	INSPECT ECT SENSOR GND CIRCUIT FOR OPEN CIRCUIT Check continuity between ECT sensor terminal B (harness-side) and PCM terminal 4O (harness-side). Is there continuity?	Yes	Go to the next step.
8		No	Repair or replace harness for open circuit, then go to the next step.
9	VERIFY TROUBLESHOOTING OF DTC P0118 COMPLETED Make sure to connect all disconnected connectors. Clear the DTC from the PCM memory using the WDS or equivalent. Start engine. Is same DTC present?	Yes	Replace PCM, then go to the next step.
9		No	Go to the next step.
10	VERIFY AFTER REPAIR PROCEDURE Perform the "AFTER REPAIR PROCEDURE ". (See AFTER REPAIR PROCEDURE ) Is any DTC present?	Yes	Go to the applicable DTC inspection. (See DTC TABLE )
10		No	Troubleshooting completed.