Diagnostic procedure

WARNING: This page is about a different car, the 2009 Mazda 6. However, it is still accessible from the selected car via links, so may be relevant.

STEP	INSPECTION	RESULTS	ACTION
1	What color is smoke coming from the exhaust system?	Blue	Burning oil is indicated. Go to the next step.
		White	Water in combustion is indicated. Go to Step 3.
		Black	Rich fuel mixture is indicated Go to Step 4
2	Inspect the PCV valve Is the PCV valve normal?	Yes	Inspect for the following: Damaged valve guide, stems or valve seals Blocked oil drain passage in cylinder head Piston ring is not seated, seized or worn. Damaged cylinder bore If other driveability symptoms are present, return to diagnostic index to service any additional symptoms.
2	Inspect the PCV valve Is the PCV valve normal?	No	Replace the PCV valve
3	Does the cooling system hold pressure?	Yes	Inspect for the following: Cylinder head gasket leakage Intake manifold gasket leakage Cracked or porous engine block If other driveability symptoms are present, return to diagnostic index to service any additional symptoms.
3	Does the cooling system hold pressure?	No	Inspect for cause
4	Inspect for the following. Air cleaner restriction Collapsed or restricted intake-air system Restricted fuel return line Are all items normal?	Yes	Go to the next step.
4		No	Service if necessary. Repeat Step 4
5	Connect the M-MDS to the DLC-2 Switch ignition to ON (Engine off) Retrieve any DTCs. Are there any DTCs displayed?	Yes	DTC is displayed: Go to the appropriate DTC inspection. (See DTC TABLE [MZI-3.7] .)
5		No	No DTC is displayed: Go to the next step.
6	Install the fuel pressure gauge between the fuel pipe and the fuel distributor Start the engine and idle it Measure fuel line pressure during idle Is fuel line pressure correct during idle? (See FUEL LINE PRESSURE INSPECTION [MZI-3.7] .)	Yes	Go to the next step.
6		No	Low: Perform "Fuel Pump Operation Inspection" and "Fuel Pump Control System Operation Inspection", repair or replace according to inspection results. Inspect the fuel line for clogging. If there is no malfunction, replace the fuel pump unit (See FUEL PUMP UNIT REMOVAL/INSTALLATION [MZI-3.7] .) High: Perform "Fuel Pump Control System Operation Inspection", repair or replace according to inspection results. If there is no malfunction, replace the fuel pump unit. (See FUEL PUMP UNIT REMOVAL/INSTALLATION [MZI-3.7] .)
7	Perform the spark test (See ENGINE CONTROL SYSTEM OPERATION INSPECTION [MZI-3.7] .) Is strong blue spark visible at each cylinder?	Yes	Inspect the CMP sensor. (See CAMSHAFT POSITION (CMP) SENSOR INSPECTION [MZI-3.7] .)
7		No	Repair or replace the malfunctioning part according to spark test result.
8	Verify test results. If normal, return to diagnostic index to service any additional symptoms (See SYMPTOM DIAGNOSTIC INDEX [MZI-3.7] .) If malfunction remains, inspect related Service Bulletins and/or On-line Repair Information and perform repair or diagnosis If vehicle is repaired, troubleshooting completed. If vehicle is not repaired or additional diagnostic information is not available, reprogram the PCM if a later calibration is available. Retest.