Diagnostic procedure

WARNING: This page is about a different car, the 2005 Mazda 6. However, it is still accessible from the selected car via links, so may be relevant.

NO. 15 EMISSION COMPLIANCE [AJ] DIAGNOSTIC PROCEDURE

STEP	INSPECTION		ACTION
1	Inspect the following: Vacuum lines for leakage or blockage Electrical connections Proper maintenance schedule followed Intake-air system and air cleaner element concerns: obstructions, leakage or dirtiness Are all items okay?	Yes	Go to the next step.
1		No	Service as necessary. Repeat Step 1.
2	Connect WDS or equivalent to DLC-2. Turn ignition switch to ON position (Engine OFF). Retrieve any DTCs. Are there any DTCs displayed?	Yes	DTC is displayed: Go to appropriate DTC test.
2		No	No DTC is displayed: Go to the next step.
3	Is any other driveability concern present?	Yes	Go to appropriate symptom troubleshooting.
3	Is any other driveability concern present?	No	Go to the next step.
4	Connect WDS or equivalent to DLC-2. Access ECT PID. Warm up engine and run it at idle. Verify ECT PID is correct. (See PCM INSPECTION .) Is ECT PID correct?	Yes	Go to the next step.
4		No	Inspect for coolant leakage. Inspect cooling fan and operation or thermostat operation.
5	Perform spark test. (See SPARK TEST .) Is strong blue spark visible at each cylinder?	Yes	Inspect for the following: Spark plugs malfunction CMP sensor is installed improperly. Damage of trigger wheel on camshaft Open or short circuit on CMP sensor Open or short circuit between CMP sensor and PCM terminal 2, 28, 54 or 80. Repair or replace malfunctioning part. If okay, go to the next step.
5		No	Repair or replace malfunctioning part according to spark test results.
6	Install fuel pressure gauge between plastic fuel hose and fuel distributor. Start engine and run it at idle. Measure fuel line pressure at idle. (See FUEL LINE PRESSURE INSPECTION .) Is fuel line pressure correct at idle?	Yes	Go to the next step.
6		No	Zero or low: Inspect fuel pump relay and fuel pump circuit. Inspect for clogged fuel line. If okay, replace fuel pump unit. (See FUEL PUMP UNIT REMOVAL/INSTALLATION .) High: Replace fuel pump unit. (See FUEL PUMP UNIT REMOVAL/INSTALLATION .)
7	Remove and shake PCV valve. Does PCV valve rattle?	Yes	Go to the next step.
7	Remove and shake PCV valve. Does PCV valve rattle?	No	Replace PCV valve.
8	Inspect for fuel saturation inside charcoal canister. Is excess amount of liquid fuel present in canister?	Yes	Replace charcoal canister.
8		No	Inspect fuel tank vent system. Then, go to the next step.
9	Inspect WU-TWC. Is WU-TWC okay?	Yes	Inspect EGR system.
9	Inspect WU-TWC. Is WU-TWC okay?	No	Replace WU-TWC.
10	Inspect for restriction in the exhaust system. Is there any restriction?	Yes	Inspect exhaust system.
10		No	Go to the next step.
11	Verify test results. If okay, return to diagnostic index to service any additional symptoms. 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 PCM if later calibration is available. Retest.