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 P0126, P0128 [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 FOR OTHER DTCs Have other DTCs been stored?	Yes	Repair circuit malfunction for applicable DTCs.
3	INSPECT FOR OTHER DTCs Have other DTCs been stored?	No	Go to the next step.
4	VERIFY COOLANT THERMOSTAT OPERATION Turn off E/L and A/C. Remove fan relay located next to main relay box. Warm up engine until ECT PID reads 99 °C {210 °F}. Short fan relay terminals A and B (harness-side) using a jumper wire. Monitor ECT PID. Has ECT PID decreased continuously and stop at 84-88 °C {184-190 °F} (thermostat closed)?	Yes	Go to Step 6.
4		No	Go to the next step.
5	INSPECT COOLANT THERMOSTAT FOR BEING STUCK OPEN Remove coolant thermostat and inspect for stuck open. (See THERMOSTAT INSPECTION .) Is thermostat okay?	Yes	Inspect ECT sensor. Replace ECT sensor if necessary, go to the next step.
5		No	Replace coolant thermostat, then go to the next step.
6	VERIFY MONITORING CONDITION FOR REPAIR VERIFICATION Make sure to connect all disconnected connectors. Cool down engine. NOTE: If workshop interior/outdoor temperature difference is significant, PCM might not operate thermostat monitor. Therefore, it is recommended to cool down engine outside of workshop. Turn ignition key to ON (Engine off). Clear the DTC from the PCM memory using the WDS or equivalent. Access ECT and IAT PIDs and make sure that each value is within following conditions. IAT is above -10 °C {14 °F}. Difference between ECT and IAT is below 6 °C {10.8°F}. Is there any PID that is out of specification?	Yes	Take corrective action (e.g. cool down engine), repeat this step.
6		No	Go to the next step for DTC P0126. Go to Step 8 for DTC P0128.
7	VERIFY TROUBLESHOOTING OF DTC P0126 COMPLETED Start engine and turn off E/L and A/C. Access DIAGNOSIS MONITORING TEST RESULTS function and monitor TEST #10: 32: 00. Drive vehicle from 40-100 km/h {25-62.5 mph} until TEST value is changed. NOTE: This test requires actual driving. Chassis roller cannot be used for this test. Therefore, it is recommended to cool down engine outside of workshop. During test drive, constant speed should be maintained, although 2 or 3 stops is acceptable during every 5 min of driving time (e.g. for traffic signals). Stop-and-go (e.g. in case of traffic congestion) is not acceptable during the test period. Test period depends on ECT at engine start, (e.g. If ECT is -10 °C {14 °F}, monitoring period is 38 min and if ECT is 30 °C {86 °F}, monitoring period is 8 min. Therefore, it is recommended to cool down engine out of workshop.) Verify TEST #10: 32: 00 value. Is value above minimum value?	Yes	Repair terminal, then go to Step 9.
7		No	Go to the next step.
8	VERIFY TROUBLESHOOTING OF DTC P0128 COMPLETED Make sure to connect all disconnected connectors. Cool down engine. Turn ignition key to ON (Engine off). Clear the DTC from the PCM memory using the WDS or equivalent. Access ECT PID and make sure that ECT PID is within -7-35 °C {20-95 °F}. Start engine. Warm up engine without depressing accelerator pedal until ECT PID reaches above 71°C {160°F}. Drive vehicle at 9.5 km/h {6 mph} or above. Access DIAGNOSTIC MONITORING TEST RESULTS function. Verify TEST #10: 31: 00 values. Is value below maximum value?	Yes	Go to the next step.
8		No	Replace PCM, then go to the next step.
9	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 .)
9		No	Troubleshooting completed.