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	Verify the following Vacuum connection Restriction in intake-air system (such as air cleaner element, fresh air duct) No air leakage from intake-air system No restriction of intake-air system Proper sealing of intake manifold and components attached to intake manifold Fuel quality (such as proper octane, contamination, winter/summer blend) Are all items normal?	Yes	Go to the next step.
1		No	Service if necessary. Repeat Step 1
2	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] .)
2		No	No DTC is displayed: Go to the next step.
3	Is the engine overheating?	Yes	Go to symptom troubleshooting "No. 17 Cooling system concerns-Overheating" (See NO. 17 COOLING SYSTEM CONCERNS-OVERHEATING [MZI-3.7] .)
3	Is the engine overheating?	No	Go to the next step
4	Connect the M-MDS to the DLC-2. Access APP1, APP2, RPM, MAF, TP1, TP2, IAT and VSS PIDs. Drive vehicle while monitoring PIDs. Are PIDs within specifications? (See PCM INSPECTION [MZI-3.7] .)	Yes	Go to the next step
4		No	APP1, APP2 PIDs: Inspect if output signal accelerator pedal position sensor changes smoothly. RPM PID: Inspect CKP sensor and related wiring harness for vibration or intermittent open/short circuit or both MAF PID: Inspect for intermittent open circuit of MAF sensor and related wiring harness. TP1, TP2 PID: Inspect if output signal TP sensor changes smoothly. IAT PID: Inspect for air suction in intake-air system. If normal, inspect intermittent short circuit of IAT sensor and related wiring harnesses VSS PID: Inspect for intermittent open circuit of VSS and related wiring harness.
5	Visually inspect the CKP sensor and teeth of crankshaft pulley Are the CKP sensor and teeth of crankshaft pulley normal?	Yes	Go to the next step.
5		No	Replace the malfunctioning part.
6	Inspect the spark plug condition Is spark plug wet, covered with carbon or grayish white?	Yes	Spark plug is wet or covered with carbon: Inspect the fuel injector for fuel leakage. Inspect spark plug and high-tension lead. Spark plug is grayish white: Inspect the fuel injector for clogging
6		No	Install the spark plugs on original cylinders. Go to the next step.
7	Perform electronic throttle control system operation inspection. (See ENGINE CONTROL SYSTEM OPERATION INSPECTION [MZI-3.7] .) Does electronic throttle control system function properly?	Yes	Go to the next step.
7		No	Repair or replace the malfunctioning part according to electronic throttle control system operation inspection results.
8	visually inspect deformed exhaust system part. Is there any deformed exhaust system part?	Yes	Replace the suspected part.
8		No	Go to the next step.
9	Install the fuel pressure gauge between the fuel pipe and the fuel distributor. Measure the fuel line pressure Is fuel line pressure correct? (See FUEL LINE PRESSURE INSPECTION [MZI-3.7] .)	Yes	Go to the next step
9		No	Zero or 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 Operation Inspection" and "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] .)
10	Perform the Fuel Pump Speed Control Inspection. (See ENGINE CONTROL SYSTEM OPERATION INSPECTION [MZI-3.7] .) Does the fuel pump speed control work properly?	Yes	Go to the next step.
10		No	Repair or replace malfunctioning part, according to inspection results
11	NOTE: The following test is for engine stalling with the A/C on concern If other symptoms exist, go to the next step Connect pressure gauge to the A/C low and high side pressure linesTurn the A/C on and measure low side and high side pressuresAre pressures within specifications?(See REFRIGERANT PRESSURE CHECK )	Yes	Go to the next step
11		No	If A/C is always on, go to symptom troubleshooting "No. 24 A/C is always on or A/C compressor runs continuously" (See NO. 24 A/C IS ALWAYS ON OR A/C COMPRESSOR RUNS CONTINUOUSLY [MZI-3.7] .) For other symptoms, inspect the following. Refrigerant charging amount Condenser fan operation
12	Inspect for A/C cut-off operation (See ENGINE CONTROL SYSTEM OPERATION INSPECTION [MZI-3.7] .) Does the A/C cut-off function properly?	Yes	Go to the next step
12		No	Inspect A/C cut-off system components.
13	Disconnect the vacuum hose between the purge solenoid valve and the intake manifold from purge solenoid valve side Plug opening end of vacuum hose Drive the vehicle Does the engine condition improve?	Yes	Inspect if purge solenoid valve is stuck open mechanically Inspect the evaporative emission control system (See ENGINE CONTROL SYSTEM OPERATION INSPECTION [MZI-3.7] .)
13		No	Go to the next step
14	Visually inspect the CMP sensor and projections of camshaft pulley Are the CMP sensor and projections of camshaft pulley normal?	Yes	Go to the next step.
14		No	Replace the malfunctioning part
15	Inspect the variable valve timing control system operation (See ENGINE CONTROL SYSTEM OPERATION INSPECTION [MZI-3.7] .) Does the variable valve timing control system function properly?	Yes	Go to the next step.
15		No	Repair or replace the malfunctioning part according to variable valve timing control system inspection results.
16	Is the engine compression correct?	Yes	Inspect the PCV valve If the PCV valve is normal, inspect the following. Valve timing Internal transaxle components Brake system for dragging
16	Is the engine compression correct?	No	Inspect for cause
17	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.