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 P0300 [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 OR STORED DTCs Turn ignition key to OFF then ON (Engine off). Verify related pending code or stored DTCs. Is other DTCs present?	Yes	Go to appropriate DTC troubleshooting. (See DTC TABLE )
3		No	Go to the next step.
4	VERIFY CURRENT INPUT SIGNAL STATUS (IGNITION KEY AT ON/IDLE) Access ECT, IAT, MAF, RPM, TP and VSS PIDs using the WDS or equivalent. (See USING SST (WDS OR EQUIVALENT) ) Is there any signal that is far out of specification when ignition switch is ON and engine is idling?	Yes	Inspect suspected circuit and/or part according to inspection results, then go to Step 22. (See USING SST (WDS OR EQUIVALENT) )
4		No	Go to the next step.
5	VERIFY CURRENT INPUT SIGNAL STATUS UNDER TROUBLE CONDITION Inspect same PIDs with step 4 while simulating FREEZE FRAME DATA condition. Is there any signal which causes drastic changes?	Yes	Inspect suspected circuit and/or part according to inspection results, then go to Step 22. (See USING SST (WDS OR EQUIVALENT) )
5		No	Go to the next step.
6	INSPECT CMP SENSOR Inspect CMP sensor. (See CAMSHAFT POSITION (CMP) SENSOR INSPECTION ) Is CMP sensor okay?	Yes	Go to the next step.
6		No	Inspect installation condition and damage on timing belt and gears, repair faulty parts. If it is okay, replace CMP sensor. Go to Step 22.
7	VERIFY CKP SENSOR INSTALLATION CONDITION Check for CKP sensor looseness. Is CKP sensor loose?	Yes	Retighten CKP sensor, then go to Step 22.
7		No	Go to the next step.
8	CHECK IGNITION COIL OPERATION AND HIGH-TENSION LEAD WITH TIMING LIGHT Verify blinking condition on each cylinder using timing light at idle. Do all cylinders show blinking condition?	Yes	Go to Step 12.
8		No	Go to the next step.
9	CHECK HIGH-TENSION LEADS OF NO BLINKING CYLINDER Turn the ignition switch off. Inspect high-tension leads for installation condition, corrosion on terminal, open circuit lead, and damaged cover. Is condition of high-tension lead okay?	Yes	Go to the next step.
9		No	Replace faulty high-tension lead, then go to Step 22.
10	INSPECT POWER SUPPLY TERMINAL AT IGNITION COIL CONNECTOR Disconnect ignition coil connector. Turn ignition key to ON (Engine off). Measure voltage between ignition coil terminal A (harness-side) and body GND. Is voltage reading B+ ?	Yes	Go to the next step.
10		No	Check for open circuit between ignition coil connector and ignition switch. Repair or replace wiring harness, then go to Step 22.
11	INSPECT IGNITION COIL RESISTANCE Check ignition coil resistance. (See IGNITION COIL INSPECTION ) Is coil resistance okay?	Yes	Go to Step 22.
11		No	Replace ignition coil, then go to Step 22.
12	INSPECT MAF PID Start engine. Access MAF PID using the WDS or equivalent. Verify that MAF PID changes quickly according to race engine RPM. Is MAF PID response okay?	Yes	Go to the next step.
12		No	Replace MAF sensor, then go to Step 22.
13	INSPECT EXCESSIVE AIR SUCTION IN INTAKE-AIR SYSTEM Inspect for air leakage at following: Between MAF sensor and TB Between TB and dynamic chamber Is there any malfunction?	Yes	Repair or replace suspected part, then go to Step 22.
13		No	Go to the next step.
14	INSPECT FUEL LINE PRESSURE Inspect fuel line pressure. (See FUEL LINE PRESSURE INSPECTION ) Is fuel line pressure okay?	Yes	Go to Step 17.
14		No	If fuel line pressure is excess high, check as follows: FP maximum pressure (See FUEL PUMP (FP) INSPECTION ) Fuel return line for clogged If all above are okay, replace pressure regulator. Go to Step 22. If fuel line pressure is too low, go to the next step.
15	INSPECT FP MAXIMUM PRESSURE Inspect FP maximum pressure. (See FUEL PUMP (FP) INSPECTION ) Is FP maximum pressure less than 640 kPa {6.5 kgf/cm2, 92 psi} ?	Yes	Go to the next step.
15		No	Inspect FP circuit for open circuit or poor connection. Repair or replace suspected circuit, then go to Step 22. If okay, replace FP, go to Step 22.
16	INSPECT FUEL LINE FROM FP TO FUEL DELIVERY PIPE Visually inspect for fuel leakage in fuel line. Is any fuel leakage found?	Yes	Replace suspected fuel line, then go to Step 22.
16		No	Inspect fuel filters for following: Restriction or clogging at fuel filter (high-pressure side). Foreign materials or stain inside fuel filter (low-pressure side) Perform following actions as result. If restriction or clogging is found at fuel filter (high-pressure side), replace fuel filter. If foreign materials or stain is found inside fuel filter (low-pressure side), clean of fuel tank and filter. If all items above are okay, replace pressure regulator. Go to Step 22.
17	INSPECT ENGINE COMPRESSION Inspect engine compression. (See COMPRESSION INSPECTION ) Is it normal?	Yes	Go to the next step.
17		No	Implement engine overhaul for repairs, then go to Step 22.
18	INSPECT OPERATION OF PURGE CONTROL SOLENOID VALVE Inspect purge solenoid valve. (See PURGE SOLENOID VALVE INSPECTION ) Is purge control solenoid valve operation okay?	Yes	Go to the next step.
18		No	Replace purge control solenoid valve, then go to Step 22.
19	INSPECT PCV VALVE OPERATION Turn the ignition switch off. Remove PCV valve and check valve operation. (See PCV VALVE INSPECTION ) Is PCV valve operation okay?	Yes	Go to the next step.
19		No	Replace PCV valve, then go to Step 22.
20	INSPECT OPERATION OF EGR VALVE Remove EGR valve. Visually check for stuck open condition. Is EGR valve stuck open?	Yes	Repair or replace EGR valve, then go to Step 22.
20		No	Go to the next step.
21	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 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 at 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 the next step.
21		No	Go to the next step.
22	VERIFY TROUBLESHOOTING OF MISFIRE DTC 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. Start engine and perform DRIVE MODE 1. (See MODE 1 (PCM ADAPTIVE MEMORY PRODUCTION DRIVE MODE) ) Is PENDING CODE or stored code for this DTC present?	Yes	Replace PCM, then go to the next step.
22		No	Go to the next step.
23	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 )
23		No	Troubleshooting completed.