EGR System Malfunction

DTC DETECTION CONDITION POSSIBLE COUSES CHART

DTC P0400, P0403, P1408	EGR SYSTEM MALFUNCTION
DETECTION CONDITION	P0400: The EEGR system is monitored once per drive cycle during steady state conditions above 48 mph. The test will fail when a malfunction is detected by PCM calculations indicating the EGR flow is less or greater than expected. P0403: The EEGR system is continuously monitored to check the 4 EEGR motor coils, circuits, and the PCM for opens, shorts to power and ground. P1408: This test is carried out during the KOER on demand self-test only. The EGR system is commanded ON at a fixed engine speed. The test fails and the DTC is output when the measured EGR flow falls above or below the required calibration.
POSSIBLE CAUSES	EEGR valve stuck open or closed Connector to EEGR not seated EEGR motor windings shorted or open circuit No power to EEGR Harness open or shorted to power or ground Vacuum signal to MAP restricted or leaking MAF sensor signal erroneous Damaged PCM Carbon build up in EEGR valve seat area One or more sensor not responding or out-of-range
HINT	EGR System Description Receives signals from the engine coolant temperature (ECT) sensor, intake air temperature (IAT) sensor, throttle position (TP) sensor, mass air flow (MAF) sensor, and crankshaft position (CKP) sensor to provide information on engine operating conditions to the PCM. The engine must be warm, stable and running at a moderate load and RPM before the EGR system is activated. The PCM deactivates EGR during idle, extended wide open throttle or whenever a failure is detected in an EGR component or EGR required component. Electronic Exhaust Gas Recirculation (EEGR) Valve Description The EEGR system receives signals from the engine coolant temperature (ECT) or cylinder head temperature (CHT) sensor, throttle position (TP) sensor, mass air flow (MAF) sensor, crankshaft position (CKP) sensor and the manifold absolute pressure (MAP) sensor to provide information on engine operating conditions to the PCM. The engine must be warm, stable and running at a moderate load and RPM before the EEGR system is activated. The PCM will deactivate EEGR during idle, extended wide open throttle or whenever a failure is detected in an EEGR component or EGR required input.
Courtesy of MAZDA MOTORS CORP.
Courtesy of MAZDA MOTORS CORP.

DTC DETECTION CONDITION POSSIBLE COUSES CHART

STEP	INSPECTION		ACTION
1	PCM QUICK TEST Was PCM Quick Test carried out?	Yes	For DTC P0403: GO to the next step. For DTC P0400 or P1408: GO to step 8.
1	PCM QUICK TEST Was PCM Quick Test carried out?	No	Carry out the PCM Quick Test. See PCM QUICK TEST .
2	CHECK FOR VPWR AT THE EEGR HARNESS CONNECTOR Key ON, engine OFF (KOEO). EEGR assembly connector disconnected. Measure the voltage between the EGR connector pins 2 and 5, harness side and ground. Is the voltage above 10 V?	Yes	GO to the next step.
2		No	KEY in OFF position. REPAIR open circuit. GO to step 11.
3	CHECK EEGR CIRCUIT(S) FOR OPEN IN HARNESS Key OFF. Disconnect the PCM connector. Measure the resistance between EGR connector pin 1 and PCM pin E14. Measure the resistance between EGR connector pin 3 and PCM pin E15. Measure the resistance between EGR connector pin 4 and PCM pin E16. Measure the resistance between EGR connector pin 6 and PCM pin E17. Are the resistances less than 5 ohms?	Yes	GO to the next step.
3		No	REPAIR open circuit. GO to step 11.
4	CHECK EEGR CIRCUIT(S) FOR SHORT TO GROUND IN HARNESS Measure the resistance between EGR connector pin 1 and ground. Measure the resistance between EGR connector pin 3 and ground. Measure the resistance between EGR connector pin 4 and ground. Measure the resistance between EGR connector pin 6 and ground. Are the resistances below 10K ohms?	Yes	GO to the next step.
4		No	REPAIR short circuit. GO to step 11.
5	CHECK FOR SHORTS BETWEEN CIRCUITS IN EEGR HARNESS Measure the resistance between EGR connector pin 1 and EGR connector pin 3. Measure the resistance between EGR connector pin 1 and EGR connector pin 4. Measure the resistance between EGR connector pin 1 and EGR connector pin 6. Measure the resistance between EGR connector pin 3 and EGR connector pin 4. Measure the resistance between EGR connector pin 3 and EGR connector pin 6. Measure the resistance between EGR connector pin 6 and EGR connector pin 4. Are the resistances below 10K ohms?	Yes	GO to the next step.
5		No	REPAIR short circuit. GO to step 11.
6	CHECK EEGR CIRCUIT FOR SHORT TO POWER IN HARNESS PCM connector connected. Key ON, engine OFF (KOEO). Measure the voltage between the EGR connector pin 1 and ground. Measure the voltage between the EGR connector pin 3 and ground. Measure the voltage between the EGR connector pin 4 and ground. Measure the voltage between the EGR connector pin 6 and ground. Are the voltages above 0.1 V?	Yes	Key in OFF position. REPAIR short circuit. GO to step 11.
6		No	GO to the next step.
7	CHECK EEGR FOR OPEN AND SHORT CIRCUITS KEY in OFF position. PCM connector disconnected. EEGR Assembly connector connected. Measure the resistance between the PCM pin E14 and PCM pin B67. Measure the resistance between the PCM pin E15 and PCM pin B67. Measure the resistance between the PCM pin E16 and PCM pin B67. Measure the resistance between the PCM pin E17 and PCM pin B67. Are the resistances between 15 ohm - 24 ohm?	Yes	GO to step 11.
7		No	INSTALL a new EEGR assembly and RETEST vehicle. See EXHAUST GAS RECIRCULATION (EGR) VALVE REMOVAL/INSTALLATION - 2.5L . GO to step 11.
9	DTCs P0400 AND P1408: CHECK FOR STUCK OR STICKY EGR VALVE OPERATION BY COMPARING ACTUAL MAP VOLTAGE TO MAP_V PID VOLTAGE NOTE: Service the following DTCs first, if present: P0102, P0103, P0107, P0108, P1100, P1101. KEY in OFF position. MAP/TMAP Sensor connector disconnected. Add 5 amp fused jumper wire between the MAP sensor connector, harness side pin 2 (VREF) and MAP sensor, component side pin 2 (VREF). Add 5 amp fused jumper wire between the MAP sensor connector, harness side pin 4 (SIGRTN) and MAP sensor, component side pin 4 (SIGRTN). Key ON, engine running (KOER). Measure the voltage between the MAP sensor connector, component side pin 1. Is the voltage between 1 V - 2 V?	Yes	Note actual MAP voltage values at KOEO, idle, 1000 and 2000 RPM. Use the values for comparison in the following test step. GO to the next step.
9		No	KEY in OFF position. CHECK MAP harness for open and short circuits. GO to step 11.
9	COMPARE ACTUAL MAP VOLTAGE TO MAP_V PID VOLTAGE EGR Key ON, engine OFF (KOEO). Access the PCM-MAP PID using a scan tool. Note MAP PID voltage. Key ON, engine running (KOER). Note MAP PID voltage. Increase engine speed to 1,000 RPM. Note MAP PID voltage. Increase engine speed to 2,000 RPM. Note MAP PID voltage. Does the MAP PID voltage stay within 0.5V of the actual MAP voltage?	Yes	Key in OFF position. Fault is not present at this time. MAKE SURE the MAP is correctly seated and the vacuum source is not blocked.
9		No	Key in OFF position. GO to the next step.
10	CARRY OUT KOER SELF-TEST Check for DTCs. Does DTC P1408 reappear?	Yes	INSTALL a new EEGR assembly. See EXHAUST GAS RECIRCULATION (EGR) VALVE REMOVAL/INSTALLATION - 2.5L . GO to step 11.
10		No	The concern is elsewhere. See DIAGNOSTIC INDEX .
11	VERIFY TROUBLESHOOTING OF DTCs COMPLETED Disconnect all the PCM connectors. Check for: corrosion damaged pins pushed-out pins Connect all connectors and make sure they seat correctly. Clear DTCs from PCM memory using IDS or equivalent tester generic OBD II tester. Carry out the PCM Quick Test. See PCM QUICK TEST . Is the same DTC present?	Yes	INSTALL a new PCM. See POWERTRAIN CONTROL MODULE (PCM) REMOVAL/INSTALLATION - 2.5L or POWERTRAIN CONTROL MODULE (PCM) REMOVAL/INSTALLATION - 3.0L . REPEAT the PCM Quick Test. See PCM QUICK TEST .
11		No	If any other DTC is present, go to applicable DTC inspection. If no DTC is present, troubleshooting complete.