DTC P0402 [YF (2.0L Zetec)]

DTC P0402	EGR flow excessive detected
DETECTION CONDITION	• The PCM monitors EGR system undesired EGR flow during idle. The monitor of EGR system looks at the D.P.F. EGR signal at idle and compares it to the stored signal measured during KOEO (Key ON engine OFF). If the signal at idle is greater than at KOEO by a calibrated amount, the PCM determines that the EGR flow is excessive.
POSSIBLE CAUSE	• EGR valve stuck open • EGR solenoid valve (vent pass) plugged • Plugged EGR tube • Slow response D.P.F. EGR sensor • D.P.F. EGR sensor damaged • Improper vacuum hose connection • Plugged vacuum hose • Short to GND in wiring between EGR solenoid valve terminal 2 and PCM terminal 79 • Damaged EGR solenoid valve • Damaged PCM


STEP	INSPECTION		ACTION
1	VERIFY FREEZE FRAME DATA HAS BEEN RECORDED • Has FREEZE FRAME DATA been recorded?	Yes	Go to the next step.
1		No	Record the FREEZE FRAME DATA on the repair order, then go to the next step.
2	VERIFY REPAIR INFORMATION AVAILABILITY • Verify related service repair information availability. • Is any related repair information available?	Yes	Perform repair or diagnosis according to the available repair information. If the vehicle is not repaired, go to the next step.
2		No	Go to the next step.
3	INDETIFY TRIGGER DTC FOR FREEZE FRAME DATA • Is DTC P0402 on FREEZE FRAME DATA?	Yes	Go to the next step.
3		No	Go to FREEZE FRAME DATA DTC inspection. (See DTC TABLE [YF (2.0L Zetec)].)
4	CHECK EGR FLOW AT IDLE WITH EGR VACUUM HOSE DISCONNECTED Note • If DTC P1405 is in continuous memory, diagnose that first starting with DTC P1405 diagnostic procedure. • Disconnect the vacuum hose at EGR valve and plug hose. • Run KOER self test. • Is KOER DTC P0403 output or unable to run KOER self test due to engine stall or no start?	Yes	Inspect pressure hoses first for pinching and icing. If normal, remove and inspect the EGR valve and EGR tube for signs of contamination, unusual wear, carbon deposits, binding and other damage. Repair or replace malfunctioning part. Then go to Step 13.
4		No	Go to the next step.
5	CHECK FOR EGR FLOW AT IDLE WITH EGR VACUUM HOSE CONNECTED • EGR vacuum hose connected. • Run KOER self test. • Is KOER DTC P0402 output or unable to run KOER self test due to engine stall or no start?	Yes	Go to the next step.
5		No	Intermittent concern exists, go to Intermittent Troubleshooting Procedure. (See INTERMITTENT CONCERN TROUBLESHOOTING [YF (2.0L Zetec)].)
6	CHECK EGR SYSTEM VACUUM HOSES FOR INTEGRITY AND CONNECTION Note • A pinched or plugged EGR vacuum hose can trap vacuum between the EGR solenoid valve and EGR valve not allowing the EGR valve to close. • Trance each vacuum hose from EGR solenoid valve and verify that the each hose is connected correctly. • Verify that the EGR valve vacuum hose is not pinched or plugged and routed properly. • Are vacuum hoses normal?	Yes	Go to the next step.
6		No	Repair or replace vacuum hose, then go to Step 13.
7	CHECK D.P.F. EGR SENSOR OUTPUT BY APPLYING VACUUM WITH HJAND PUMP • Disconnect pressure hoses at D.P.F. EGR sensor. • Connect a hand vacuum pump to the downstream connection at sensor (intake manifold side of sensor or the smaller diameter pickup tube.) • Turn the ignition switch to ON. • Access DPFEGR PID and note PID value. • Apply 27-30 kPa {8-9 inHg} vacuum to the D.P.F. EGR sensor and hold for a few seconds. • Quickly release vacuum. - The DPFEGR PID voltage must be 0.2-1.3 V with the ignition switch ON and no vacuum applied. - The DPFEGR PID voltage must increase to greater than 4.0 V with the vacuum applied. - The DPFEGR PID voltage must drop to less than 1.5 V in less than 3 s when vacuum is released. • Does the DPFEGR PID voltage indicate a fault in the D.P.F. EGR sensor?	Yes	Replace D.P.F. EGR sensor, then go to Step 13.
7		No	Reconnect the vacuum hose, then go to the next step.
8	CHECK FOR EGR FLOW AT IDLE WITH EGR SOLENOID VALVE CONNECTOR OFF • Disconnect vacuum hose at EGR valve and connect hose to vacuum gauge. • Start the engine and bring to an idle. • While monitoring vacuum gauge, disconnect the EGR solenoid valve connector. - The EGR valve requires vacuum greater than 5.4 kPa {1.6 inHg} to begin to open. If the vacuum reading remains greater than 5.4 kPa {1.6 inHg} after the EGR solenoid valve is electrically disconnected, this would indicate a mechanical fault in the EGR vacuum regulator solenoid. • Does the EGR vacuum remain greater than 5.4 kPa {1.6 inHg} at idle even after EGR solenoid valve electrically disconnected?	Yes	This indicates a fault in the EGR solenoid valve. Go to the next step.
8		No	Go to Step 10.
9	INSPECT EGR SOLENOID VALVE VEN FOR PLUGGING Note • A plugged EGR solenoid valve vent will not allow EGR vacuum vent to atmosphere. • Disconnect EGR solenoid valve hoses. • Remove EGR solenoid valve vent cap (if removable). • Remove filter and inspect for blockage or icing in some cases. • With the EGR valve vacuum source port with a hand vacuum pump. If the vacuum holds or is slow to release to atmosphere, the EGR solenoid valve vent could be plugged or restricted. • Is the EGR solenoid valve vent or vent filter plugged or restricted?	Yes	Repair plugged or restricted for EGR solenoid valve. If can not repair, replace EGR solenoid valve, then go to Step 13.
9		No	Replace EGR solenoid valve, then go to Step 13.
10	MEASURE EGR SOLENOID VALVE COIL RESISTANCE • Measure resistance across EGR solenoid valve. • Is resistance 26-40 ohms?	Yes	Go to the next step.
10		No	Replace EGR solenoid valve, then go to Step 13.
11	CHECK EGR SOLENOID VALVE CONTROL CIRCUIT FOR SHORT TO GND IN HARNESS • Disconnect the WDS or equivalent from DLC-2. • Disconnect PCM. • Measure resistance between PCM terminal 79 at harness side connector and battery negative post. • Is resistance greater than 10,000 ohms?	Yes	Go to the next step.
11		No	Repair short to ground, then go to Step 13.
12	CHECK EGR SOLENOID VALVE CONTROL CIRCUIT FOR SHORT TO VREF • Measure resistance between PCM terminal 79 and 90 at harness side connector. • Is resistance greater than 10,000 ohms?	Yes	Replace PCM, then go to the next step.
12		No	Repair short to VREF circuit, then go to the next step.
13	VERIFY TROUBLESHOOTING OF DTC P0402 COMPLETED • Make sure to reconnect all disconnected connectors. • Clear the DTC from the PCM memory using the WDS or equivalent. • Perform KOER self test. (See KOEO/KOER SELF-TEST [YF (2.0L Zetec)].) • Is the PENDING CODE same DTC present?	Yes	Replace PCM, then go to the next step. (See PCM REMOVAL/INSTALLATION [YF (2.0L Zetec)].)
13		No	Go to the next step.
14	VERIFY AFTER REPAIR PROCEDURE • Perform "After Repair Procedure". (See AFTER REPAIR PROCEDURE [YF (2.0L Zetec)].) • Is there any DTC present?	Yes	Go to the applicable DTC inspection. (See DTC TABLE [YF (2.0L Zetec)].)
14		No	Troubleshooting completed.