Electric EGR (EEGR) System Malfunction - 2.3L

DTC P0400, P0403, P1408 DETECTION CONDITION & POSSIBLE CAUSES

DTC P0400, P0403, P1408	ELECTRICAL EGR (EEGR) SYSTEM MALFUNCTION (2.3L)
DETECTION CONDITION	P0400 indicates EGR malfunction is detected by powertrain control module (PCM) calculations - EGR flow is less or greater than expected. P0403 indicates EEGR electric motor windings or circuits to the PCM are shorted or open. P1408 indicates EGR flow is out of self-test range when the EGR system is commanded on.
POSSIBLE CAUSE	EEGR valve stuck open or closed (P0400, P1408) Connector to EEGR not seated (P0400, P0403, P1408) EEGR motor windings shorted or open (P0400, P0403, P1408) No power to EEGR (P0400, P1408) Harness open or shorted to power or ground (P0400, P1408) Vacuum signal to MAP restricted or leaking (P0400, P1408) MAF sensor signal erroneous (P0400, P1408) Damaged PCM (P0400, P0403, P1408) Carbon buildup in EEGR valve seat area (P0400, P1408) One or more sensors not responding or out of range (P0400, P1408) Open or short in harness from PCM to EEGR (P0403) Short circuit in EEGR motor (P0403)
HINT	EEGR System Description Receives signals from the cylinder head temperature (CHT) sensor, intake air temperature (IAT) sensor, throttle position (TP) sensor, crankshaft position (CKP) sensor, mass air flow (MAF) sensor, and manifold absolute pressure (MAP) sensor to provide information on engine operating conditions to the PCM. After a vehicle has warmed up and normal EGR rates are being commanded by the PCM, the EGR flow check is performed. EEGR flow test rate is done by observing the behavior of two different values of MAP - the analog MAP sensor reading and the inferred MAP (MAP calculated from MAF, TP, RPM, etc). During normal, steady-state operating conditions, EEGR is commanded ON to a specified percentage. Then, EEGR is commanded OFF. If the EEGR system is working properly, there is a significant difference in both the observed and the calculated values of MAP (EEGR ON and EEGR OFF). EEGR system is disabled if a malfunction is detected. EEGR Assembly Description Controlled by the PCM with 0 to 52 discrete increments (steps) to get the valve from fully closed to fully open. Stepper motor electrical test is a continuous check of the four electric stepper motor coils and circuits to the PCM.
Courtesy of MAZDA MOTORS CORP.

DTC P0400, P0403, P1408 DIAGNOSTIC PROCEDURE

DTC P0400, P0403, P1408		ELECTRICAL EGR (EEGR) SYSTEM MALFUNCTION (2.3L)
STEP	INSPECTION		ACTION
1	Was the PCM quick test performed?	Yes	For P0403: Go to next step. For P0400/P1408: Go to step 10.
1	Was the PCM quick test performed?	No	Perform PCM quick test. See PCM QUICK TEST .
2	P0403: CHECK CONNECTION OF EEGR TO HARNESS NOTE: If the DTC was generated by an intermittent condition, maximum benefit of the following pinpoint tests will be obtained by having an assistant wiggle the harness/connectors when making measurements. Check the harness connector at the EEGR assembly. Is the connector properly seated?	Yes	Go to next step.
2		No	Firmly seat the connector. Go to step 11.
3	CHECK FOR B+ AT HARNESS CONNECTOR TO EEGR MOTOR Key on, engine off (KOEO). Disconnect EEGR connector. Measure the voltage between VPWR at the harness connector and battery negative post. Is the voltage greater than 10.5 V?	Yes	Go to next step.
3		No	Repair open supply circuit. Go to step 11.
4	CHECK EEGR HARNESS CIRCUIT FOR SHORTS TO GROUND Key OFF. Disconnect PCM. Install breakout box and leave PCM disconnected. Measure the resistance between the following PCM test pins and battery ground: PCM test pin 73 (EGRM1) PCM test pin 99 (EGRM2) PCM test pin 72 (EGRM3) PCM test pin 98 (EGRM4) Is each resistance greater than 10K ohms?	Yes	Go to next step.
4		No	Repair short to ground in the harness. Go to step 11.
5	CHECK FOR OPEN CIRCUITS IN THE EEGR HARNESS Measure the resistance of each EEGR circuit between the PCM test pin and the EEGR connector: PCM test pin 73 (EGRM1) PCM test pin 99 (EGRM2) PCM test pin 72 (EG RM3) PCM test pin 98 (EG RM4) Is resistance of each circuit greater than 5.0 ohms?	Yes	Repair open circuit.
5		No	Go to step 11.
6	CHECK EEGR HARNESS CIRCUITS FOR SHORTS TO EACH OTHER Measure the resistance between each EEGR circuit by measuring between: PCM test pin 72 and PCM test pins 73, 98, and 99 PCM test pins 73 and PCM test pins 98 and 99 PCM test pin 98 and PCM test pin 99 Is each resistance greater than 10K ohms?	Yes	Go to next step.
6		No	Repair short in harness. Go to step 11.
7	CHECK FOR SHORTS TO POWER IN THE EEGR HARNESS Remove breakout box. Reconnect PCM. Key of, engine off (KOEO). Measure the voltage between each EEGR circuit at the EEGR connector and battery negative post. Is the voltage less than 0.1 V?	Yes	Go to next step.
7		No	Repair short to power in harness. Go to step 11.
8	CHECK EEGR MOTOR WINDINGS FOR OPEN AND SHORT CIRCUITS Key OFF. Disconnect the PCM and reconnect the EEGR connector. Install breakout box and leave PCM disconnected. Measure the resistance between PCM test pin 71/97 (VPWR) and PCM test pins 73 (EGRM1), 99 (EGRM2), 72 (EGRM3) and 98 (EGRM4). Is each resistance between 20 and 24 ohms?	Yes	Go to next step.
8		No	Replace EEGR Assembly. See EXHAUST GAS RECIRCULATION (EGR) VALVE REMOVAL / INSTALLATION - 2.3L . Go to step 11.
9	CHECK EEGR MOTOR WINDINGS FOR SHORTS TO GROUND Key OFF. Measure the resistance between the following PCM test pins and battery ground: PCM test pin 73 (EGRM1) PCM test pin 99 (EGRM2) PCM test pin 72 (EGRM3) PCM test pin 98 (EGRM4) Is each resistance greater than 10K ohms?	Yes	Replace PCM. See POWERTRAIN CONTROL MODULE (PCM) REMOVAL / INSTALLATION .
9		No	Replace EEGR Assembly. See EXHAUST GAS RECIRCULATION (EGR) VALVE REMOVAL / INSTALLATION - 2.3L . Go to step 11.
10	DTC P0400/P1408: CHECK FOR STUCK EEGR VALVE OPERATION NOTE: Service any of the following DTCs first (if present): P0102, P0103, P0107, P0108, P1100, P1101. Disconnect the PCM. Install breakout box and connect PCM. Key on, engine running (KOER). Using WDS or equivalent tester, access output test mode. Access the EEGR PID (EGRMC) and the MAP PID (MAP) if available. Operate the engine at normal operating temperature between 1, 000 and 1, 200 rpm to prevent engine stalling. Add a small amount of EGR (approx. 8 to 12 steps) (with EGRMC high-lighted) while monitoring the MAP PID or the voltage at PCM test pin 63 (MAP). The MAP value should increase as EGR is introduced. NOTE: The engine rpm must be held at a fixed value during this test. Additionally, DTCs may have been generated as a result of this procedure. After running this test, clear any DTCs that may have been introduced. Is an increase in MAP value seen as EGR is introduced?	Yes	Condition is not present at this time. Make sure the MAP is properly seated and the vacuum source is not blocked. Go to next step.
10		No	Replace EEGR Assembly. See EXHAUST GAS RECIRCULATION (EGR) VALVE REMOVAL / INSTALLATION - 2.3L . Go to next step.
11	VERIFY TROUBLESHOOTING OF DTCs COMPLETED Connect all disconnected connectors. Clear DTCs from PCM memory using WDS or equivalent tester. Perform PCM quick test. Is same DTC present?	Yes	Replace PCM. See POWERTRAIN CONTROL MODULE (PCM) REMOVAL / INSTALLATION . Repeat PCM quick test.
11		No	If any other DTC is present, Go to applicable DTC inspection. See DIAGNOSTIC TROUBLE CODE (DTC) INDEX - POWERTRAIN CONTROL MODULE (PCM) . If no DTC is present, troubleshooting is complete.