Diagnostic Procedure

WARNING: This page is about a different car, the 2020 Mazda CX-30. However, it is still accessible from the selected car via links, so may be relevant.

ENGINE RUNS ROUGH/ROLLING IDLE (SKYACTIV-G, US) DIAGNOSTIC PROCEDURE

Step	Inspection	Results	Action
1	VERIFY IF MALFUNCTION INCLUDES HARD ENGINE STARTING Verify the vehicle engine condition. Can idling be maintained?	Yes	Go to the next step.
1		No	Perform the symptom troubleshooting "ENGINE STALLS-AFTER START/AT IDLE". (See ENGINE STALLS-AFTER START/AT IDLE .)
2	VERIFY IF MALFUNCTION CAUSE IS OVERHEATING WARNING: While performing this step, always operate the vehicle in a safe and lawful manner. When the M-MDS is used to observe monitor system status while driving, be sure to have another technician with you, or record the data in the M-MDS using the PID/DATA MONITOR AND RECORD capturing function and inspect later. Access the ECT PID using the MMDS. (See PID/DATA MONITOR INSPECTION .) Is the ECT PID value less than 116°C {241°F} during driving?	Yes	Go to the next step.
2		No	The cause of this concern could be from the cooling system overheating. Perform the symptom troubleshooting "COOLING SYSTEM CONCERNS-OVERHEATING". (See COOLING SYSTEM CONCERNS-OVERHEATING (US) .)
3	VERIFY PCM DTC Perform the DTC inspection for the PCM. (See DTC INSPECTION .) Are any DTCs displayed?	Yes	Repair the malfunctioning location according to the applicable DTC troubleshooting. (See DTC TABLE [PCM (SKYACTIV-G (US))] .)
3		No	Go to the next step.
4	VERIFY CURRENT INPUT SIGNAL STATUS WARNING: While performing this step, always operate the vehicle in a safe and lawful manner. When the M-MDS is used to observe monitor system status while driving, be sure to have another technician with you, or record the data in the M-MDS using the PID/DATA MONITOR AND RECORD capturing function and inspect later. Access the following PIDs using the M-MDS: (See PID/DATA MONITOR INSPECTION .) APP1 APP2 ECT ECT_VOLT ECT2 ECT2_VOLT MAF MAP MAP_VOLT A/F_SEN_CUR HO2S_OUT_VOLT SHRT_FUEL_TRIM LONG_FUEL_TRIM Do the PIDs indicate the correct values under the malfunction condition? (See PID/DATA MONITOR TABLE [PCM (SKYACTIV-G (US))] .)	Yes	Go to the next step.
4		No	APP1, APP2 PIDs are not as specified: Inspect the APP sensor No. 1 and No. 2. (See ACCELERATOR PEDAL POSITION (APP) SENSOR INSPECTION [SKYACTIV-G (VIN M (US))] .) (See ACCELERATOR PEDAL POSITION (APP) SENSOR INSPECTION [SKYACTIV-G (VIN L (US))] .) ECT, ECT_VOLT, ECT2, ECT2_VOLT PIDs are not as specified: Inspect the ECT sensor No. 1 and No. 2. (See ENGINE COOLANT TEMPERATURE (ECT) SENSOR INSPECTION [SKYACTIV-G (VIN M (US))] .) (See ENGINE COOLANT TEMPERATURE (ECT) SENSOR INSPECTION [SKYACTIV-G (VIN L (US))] .) MAF PID is not as specified: Inspect the MAF sensor. (See MASS AIR FLOW (MAF) SENSOR INSPECTION [SKYACTIV-G (VIN M (US))] .) (See MASS AIR FLOW (MAF) SENSOR INSPECTION [SKYACTIV-G (VIN L (US))] .) MAP, MAP_VOLT PIDs are not as specified: Inspect the MAP sensor. (See MANIFOLD ABSOLUTE PRESSURE (MAP) SENSOR INSPECTION [SKYACTIV-G (VIN M (US))] .) (See MANIFOLD ABSOLUTE PRESSURE (MAP) SENSOR INSPECTION [SKYACTIV-G (VIN L (US))] .) A/F_SEN_CUR, SHRT_FUEL_TRIM, LONG_FUEL_TRIM PIDs are not as specified: Inspect the A/F sensor. (See AIR FUEL RATIO (A/F) SENSOR INSPECTION [SKYACTIV-G (VIN M (US))] .) (See AIR FUEL RATIO (A/F) SENSOR INSPECTION [SKYACTIV-G (VIN L (US))] .) HO2S_OUT_VOLT PID is not as specified: Inspect the HO2S. (See HEATED OXYGEN SENSOR (HO2S) INSPECTION [SKYACTIV-G (VIN M (US))] .) (See HEATED OXYGEN SENSOR (HO2S) INSPECTION [SKYACTIV-G (VIN L (US))] .) Repair or replace the malfunctioning location. If the malfunction remains: Perform the "Action for Non-repeatable Malfunction" procedure. (See TROUBLESHOOTING PROCEDURE [(US)] .)
5	DETERMINE IF MALFUNCTION CAUSE IS A/C REQUEST SIGNAL OR OTHER Access the A/C_REQ PID using the M-MDS. (See PID/DATA MONITOR INSPECTION .) Monitor the A/C_REQ PID while turning on and off the air conditioner using the switch on the control panel. Does the A/C_REQ PID value change from on to off according to switch control panel?	Yes	Go to the next step.
5		No	If the A/C_REQ PID is always ON: Perform the symptom troubleshooting "A/C IS ALWAYS ON OR A/C COMPRESSOR RUNS CONTINUOUSLY". (See A/C IS ALWAYS ON OR A/C COMPRESSOR RUNS CONTINUOUSLY .) If the A/C_REQ PID is always OFF: Perform the symptom troubleshooting "A/C DOES NOT WORK SUFFICIENTLY". (See A/C DOES NOT WORK SUFFICIENTLY .)
6	INSPECT DRIVE-BY-WIRE CONTROL SYSTEM OPERATION Perform the Electronic Control Throttle Operation Inspection. (See ENGINE CONTROL SYSTEM OPERATION INSPECTION (US) .) Does the drive-by-wire control system work properly?	Yes	Visually inspect the throttle body (damage/scratching). If there is any malfunction: Repair or replace the malfunctioning location and perform the repair completion verification. If there is no malfunction: Go to the next step.
6		No	Repair or replace the malfunctioning location and perform the repair completion verification.
7	INSPECT FUEL INJECTOR OPERATION Perform the Fuel Injector Operation Inspection. (See FUEL INJECTOR INSPECTION [SKYACTIV-G (VIN M (US))] .) (See FUEL INJECTOR INSPECTION [SKYACTIV-G (VIN L (US))] .) Do the fuel injectors operate properly?	Yes	Go to the next step.
7		No	Repair or replace the malfunctioning location and perform the repair completion verification.
8	INSPECT PURGE CONTROL SYSTEM OPERATION Perform the Purge Control System Inspection. (See PURGE SOLENOID VALVE INSPECTION [SKYACTIV-G (VIN M (US))] .) (See PURGE SOLENOID VALVE INSPECTION [SKYACTIV-G (VIN L (US))] .) Does the purge solenoid valve work properly?	Yes	Go to the next step.
8		No	Repair or replace the malfunctioning location and perform the repair completion verification.
9	INSPECT RELATED PART CONDITION Inspect the following: Fuel quality (proper octane, contamination, winter/summer blend) Intake-air system restriction or leakage Electrical connectors connection Fuel leakage in fuel system Vacuum leakage Engine oil viscosity CKP sensor, intake CMP sensor and exhaust CMP sensor Installation condition (See CRANKSHAFT POSITION (CKP) SENSOR REMOVAL/INSTALLATION [SKYACTIV-G (VIN M (US))] .) (See CRANKSHAFT POSITION (CKP) SENSOR REMOVAL/INSTALLATION [SKYACTIV-G (VIN L (US))] .) (See CAMSHAFT POSITION (CMP) SENSOR REMOVAL/INSTALLATION [SKYACTIV-G (VIN M (US))] .) (See CAMSHAFT POSITION (CMP) SENSOR REMOVAL/INSTALLATION [SKYACTIV-G (VIN L (US))] .) Damaged trigger wheel, intake camshaft and exhaust camshaft Is there any malfunction?	Yes	Repair or replace the malfunctioning location and perform the repair completion verification.
9		No	Go to the next step.
10	INSPECT FUEL PRESSURE (HIGH-SIDE) Start the engine and warm it up completely. Access the FUEL_PRES PID using the M-MDS at idle. (See PID/DATA MONITOR INSPECTION .) Is the FUEL_PRES PID value within specification? Specification: Approx. 10 MPa {102 kgf/cm² , 1450 psi}	Yes	Go to Step 14.
10		No	Lower than specification: Inspect the following: Fuel leakage at the fuel line and fuel injector Fuel pump Perform the Fuel Pump (Low-pressure Side) Operation Inspection. (See FUEL PUMP UNIT INSPECTION [SKYACTIV-G (VIN M (US))] .) (See FUEL PUMP UNIT INSPECTION [SKYACTIV-G (VIN L (US))] .) Fuel pressure sensor (See FUEL PRESSURE SENSOR INSPECTION [SKYACTIV-G (VIN M (US))] .) (See FUEL PRESSURE SENSOR INSPECTION [SKYACTIV-G (VIN L (US))] .) High pressure fuel pump (See HIGH PRESSURE FUEL PUMP INSPECTION [SKYACTIV-G (VIN M (US))] .) (See HIGH PRESSURE FUEL PUMP INSPECTION [SKYACTIV-G (VIN L (US))] .) If there is any malfunction: Repair or replace the malfunctioning location and perform the repair completion verification. If there is no malfunction: Go to Step 13. Higher than specification: Go to the next step.
11	DETERMINE IF MALFUNCTION CAUSE IS FUEL PRESSURE SENSOR OR HIGH PRESSURE FUEL PUMP Is the vehicle acceleration performance normal?	Yes	Go to the next step.
11		No	Go to Step 13.
12	INSPECT FUEL PRESSURE SENSOR FOR MALFUNCTION Inspect the applicable part. (See FUEL PRESSURE SENSOR INSPECTION [SKYACTIV-G (VIN M (US))] .) (See FUEL PRESSURE SENSOR INSPECTION [SKYACTIV-G (VIN L (US))] .) Is the part normal?	Yes	Go to Step 14.
12		No	Replace the fuel distributor and perform the repair completion verification. (See FUEL INJECTOR REMOVAL/INSTALLATION [SKYACTIV-G (VIN M (US))] .) (See FUEL INJECTOR REMOVAL/INSTALLATION [SKYACTIV-G (VIN L (US))] .)
13	INSPECT SPILL VALVE CONTROL SOLENOID VALVE CONTROL CIRCUIT FOR SHORT TO GROUND Inspect the applicable circuit for a short to ground. (See CIRCUIT INSPECTION .) Is the circuit normal?	Yes	Replace the high pressure fuel pump and perform the repair completion verification. (See HIGH PRESSURE FUEL PUMP REMOVAL/INSTALLATION [SKYACTIV-G (VIN M (US))] .) (See HIGH PRESSURE FUEL PUMP REMOVAL/INSTALLATION [SKYACTIV-G (VIN L (US))] .)
13		No	Repair or replace the malfunctioning location and perform the repair completion verification.
14	INSPECT FUEL PRESSURE (LOW-SIDE) Connect the fuel pressure gauge between fuel pump and high pressure fuel pump. Measure the low side fuel pressure. (See FUEL LINE PRESSURE INSPECTION [SKYACTIV-G (VIN M (US))] .) (See FUEL LINE PRESSURE INSPECTION [SKYACTIV-G (VIN L (US))] .) Is the low side fuel pressure within specification? Specification: 475-555 kPa {4.85-5.65 kgf/cm² , 68.9-80.4 psi}	Yes	Go to the next step.
14		No	Inspect the following: Fuel line restriction Fuel filter clogged If there is any malfunction: Repair or replace the malfunctioning location and perform the repair completion verification. If there is no malfunction: Replace the fuel pump unit and perform the repair completion verification. (See FUEL PUMP UNIT REMOVAL/INSTALLATION [SKYACTIV-G (VIN M (US))] .) (See FUEL PUMP UNIT REMOVAL/INSTALLATION [SKYACTIV-G (VIN L (US))] .)
15	INSPECT ENGINE COMPRESSION Measure the compression pressure for each cylinder. (See COMPRESSION INSPECTION [SKYACTIV-G (VIN M (US))] .) (See COMPRESSION INSPECTION [SKYACTIV-G (VIN L (US))] .) Are compression pressures within specification?	Yes	Go to Step 21.
15		No	Go to the next step.
16	INSPECT ELECTRIC VARIABLE VALVE TIMING DRIVER FOR MALFUNCTION Inspect the applicable part. (See ELECTRIC VARIABLE VALVE TIMING MOTOR/DRIVER INSPECTION [SKYACTIV-G (VIN M (US))] .) (See ELECTRIC VARIABLE VALVE TIMING MOTOR/DRIVER INSPECTION [SKYACTIV-G (VIN L (US))] .) Is the part normal?	Yes	Go to the next step.
16		No	Repair or replace the malfunctioning location and perform the repair completion verification. (See ELECTRIC VARIABLE VALVE TIMING MOTOR/DRIVER REMOVAL/INSTALLATION [SKYACTIV-G (VIN M (US))] .) (See ELECTRIC VARIABLE VALVE TIMING MOTOR/DRIVER REMOVAL/INSTALLATION [SKYACTIV-G (VIN L (US))] .)
17	INSPECT ELECTRIC VARIABLE VALVE TIMING MOTOR FOR MALFUNCTION Inspect the applicable part. (See ELECTRIC VARIABLE VALVE TIMING MOTOR/DRIVER INSPECTION [SKYACTIV-G (VIN M (US))] .) (See ELECTRIC VARIABLE VALVE TIMING MOTOR/DRIVER INSPECTION [SKYACTIV-G (VIN L (US))] .) Is the part normal?	Yes	Go to the next step.
17		No	Repair or replace the malfunctioning location and perform the repair completion verification. (See ELECTRIC VARIABLE VALVE TIMING MOTOR/DRIVER REMOVAL/INSTALLATION [SKYACTIV-G (VIN M (US))] .) (See ELECTRIC VARIABLE VALVE TIMING MOTOR/DRIVER REMOVAL/INSTALLATION [SKYACTIV-G (VIN L (US))] .)
18	INSPECT ELECTRIC VARIABLE VALVE TIMING ACTUATOR FOR MALFUNCTION Inspect the applicable part. (See ELECTRIC VARIABLE VALVE TIMING ACTUATOR INSPECTION [SKYACTIV-G (VIN M (US))] .) (See ELECTRIC VARIABLE VALVE TIMING ACTUATOR INSPECTION [SKYACTIV-G (VIN L (US))] .) Is the part normal?	Yes	Go to the next step.
18		No	Repair or replace the malfunctioning location and perform the repair completion verification. (See ELECTRIC VARIABLE VALVE TIMING ACTUATOR, HYDRAULIC VARIABLE VALVE TIMING ACTUATOR REMOVAL/INSTALLATION [SKYACTIV-G (VIN M (US))] .) (See ELECTRIC VARIABLE VALVE TIMING ACTUATOR, HYDRAULIC VARIABLE VALVE TIMING ACTUATOR REMOVAL/INSTALLATION [SKYACTIV-G (VIN L (US))] .)
19	INSPECT HYDRAULIC VARIABLE VALVE TIMING CONTROL SYSTEM OPERATION Perform the Hydraulic Variable Valve Timing Control System Operation Inspection. (See OCV FOR HYDRAULIC VARIABLE VALVE TIMING SYSTEM INSPECTION [SKYACTIV-G (VIN M (US))] .) (See OIL CONTROL VALVE (OCV) INSPECTION [SKYACTIV-G (VIN L (US))] .) Is there any malfunction?	Yes	Repair or replace the malfunctioning location and perform the repair completion verification.
19		No	Go to the next step.
20	INSPECT FOR MALFUNCTION DUE TO DEVIATED VALVE TIMING Inspect the valve timing (timing chain installation condition). (See TIMING CHAIN REMOVAL/INSTALLATION [SKYACTIV-G (VIN M (US))] .) (See TIMING CHAIN REMOVAL/INSTALLATION [SKYACTIV-G (VIN L (US))] .) Is the valve timing normal?	Yes	Inspect for the following engine internal parts: Cylinder Piston ring Intake valve Exhaust valve Such as cylinder head gasket If there is any malfunction: Repair or replace the malfunctioning location and perform the repair completion verification.
20		No	Adjust the valve timing to the correct timing and perform the repair completion verification.
21	INSPECT IGNITION SYSTEM OPERATION Perform the Spark Test. (See SPARK INSPECTION [SKYACTIV-G (VIN M (US))] .) (See SPARK INSPECTION [SKYACTIV-G (VIN L (US))] .) Is a strong blue spark visible at each cylinder?	Yes	Go to the next step.
21		No	Repair or replace the malfunctioning location and perform the repair completion verification.
22	INSPECT EXHAUST SYSTEM FOR RESTRICTION Inspect for restriction in the exhaust system and the TWC. Is there any restriction?	Yes	Repair or replace the malfunctioning location and perform the repair completion verification.
22		No	Go to the next step.
23	INSPECT IF MALFUNCTION CAUSE IS PCV VALVE OR INJECTOR DRIVER (PCM INTEGRATED) Inspect the PCV valve. (See POSITIVE CRANKCASE VENTILATION (PCV) VALVE INSPECTION [SKYACTIV-G (VIN M (US))] .) (See POSITIVE CRANKCASE VENTILATION (PCV) VALVE INSPECTION [SKYACTIV-G (VIN L (US))] .) Is there any malfunction?	Yes	Replace the PCV valve and perform the repair completion verification. (See POSITIVE CRANKCASE VENTILATION (PCV) VALVE REMOVAL/INSTALLATION [SKYACTIV-G (VIN M (US))] .) (See POSITIVE CRANKCASE VENTILATION (PCV) VALVE REMOVAL/INSTALLATION [SKYACTIV-G (VIN L (US))] .)
23		No	Injector driver malfunction. Replace the PCM. (See PCM REMOVAL/INSTALLATION [SKYACTIV-G (VIN M (US))] .) (See PCM REMOVAL/INSTALLATION [SKYACTIV-G (VIN L (US))] .) If the problem remains, overhaul the engine and perform the repair completion verification.
Repair completion verification 1	VERIFY THAT VEHICLE IS REPAIRED Install/connect the part removed/disconnected during the troubleshooting procedure. Has the malfunction symptom been eliminated?	Yes	Complete the symptom troubleshooting. (Explain contents of repair to customer)
Repair completion verification 1		No	Refer to the controller area network (CAN) malfunction diagnosis flow to inspect for a CAN communication error. (See CONTROLLER AREA NETWORK (CAN) MALFUNCTION DIAGNOSIS FLOW [(US)] .) If the CAN communication is normal, perform the diagnosis from Step 1. If the malfunction recurs, go to the next step.
Repair completion verification 2	VERIFY IF MALFUNCTION IS CAUSED BY NOT PERFORMING PCM REPROGRAMMING Verify repair information and verify that there is a new calibration in the PCM. Is there a new calibration in the PCM?	Yes	Perform the PCM reprogramming and verify if the malfunction symptom was corrected. If the malfunction recurs, replace the PCM. (See PCM REMOVAL/INSTALLATION [SKYACTIV-G (VIN M (US))] .) (See PCM REMOVAL/INSTALLATION [SKYACTIV-G (VIN L (US))] .)
Repair completion verification 2		No	Replace the PCM. (See PCM REMOVAL/INSTALLATION [SKYACTIV-G (VIN M (US))] .) (See PCM REMOVAL/INSTALLATION [SKYACTIV-G (VIN L (US))] .)