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 P0140 [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	VERIFY RELATED PENDING CODE AND STORED DTCS Turn ignition key to OFF, then ON (Engine off). Verify pending code and stored DTCs using the WDS or equivalent. Is other DTC present except P0131 and P0132?	Yes	Go to appropriate DTC troubleshooting procedures. (See DTC TABLE )
3		No	Go to the next step.
4	IDENTIFY TRIGGER DTC FOR FREEZE FRAME DATA Is DTC P0140 on FREEZE FRAME DATA?	Yes	Go to the next step.
4		No	Go to troubleshooting procedures for DTC on FREEZE FRAME DATA. (See DTC TABLE )
5	VERIFY CURRENT INPUT SIGNAL STATUS Warm up engine. Access O2S12 PID using the WDS or equivalent. Verify PID when racing engine at least 10 times (in PARK (AT), NEUTRAL (MT)). Is PID reading okay? More than 0.55 V at least once during engine racing.	Yes	Go to Step 8.
5		No	Go to the next step.
6	INSPECT INSTALLATION OF HO2S (REAR) Check if HO2S (rear) is loosely installed. Is sensor installed securely?	Yes	Go to the next step.
6		No	Install sensor securely, then go to Step 10.
7	INSPECT GAS LEAKAGE FROM EXHAUST SYSTEM Visually check if there is any gas leakage between exhaust pipe and HO2S (rear). Is there gas leakage?	Yes	Repair or replace any faulty exhaust parts, then go to Step 10.
7		No	Inspect the following harnesses for open circuit or short to GND circuit, repair or replace harness if necessary. HO2S (rear) terminal A (harness-side) to PCM terminal 4AA (harness-side) Repair or replace harness if necessary. If all items above are okay, replace faulty sensor. Go to Step 10.
8	INSPECT SEALING OF ENGINE COOLANT PASSAGE WARNING: Removing radiator cap when radiator is hot is dangerous. Scalding coolant and steam may shoot out and cause serious injury. When removing radiator cap, wrap a thick cloth around and turn it slowly. Remove radiator cap. Implement procedure to bleed air from engine coolant, then idle engine. Are there any small bubbles, which makes engine coolant white the filler opening? NOTE: Large bubbles are normal since they remain air coming out from engine coolant passage.	Yes	Air gets in from poor sealing on head gasket or other areas between combustion chamber and engine coolant passage. Repair or replace faulty parts, then go to Step 10.
8		No	Go to the next step.
9	INSPECT ENGINE COMPRESSION Inspect engine compression. (See COMPRESSION INSPECTION ) Is it normal?	Yes	Go to the next step.
9		No	Implement engine overhaul for repairs, then go to the next step.
10	VERIFY TROUBLESHOOTING OF DTC P0140 COMPLETED Make sure to reconnect all disconnected connectors. Turn ignition key to ON (Engine off). Clear the DTC from the PCM memory using the WDS or equivalent. Access RPM and ECT PIDs. Verify that ECT PID is reading above 70°C {158°F} . Increase engine speed above 1,500 rpm (RPM PID reading) more than 54.2 s. Is same DTC present?	Yes	Replace PCM, then go to the next step.
10		No	Go to the next step.
11	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 )
11		No	Troubleshooting completed.