P0401
DTC P0401 / P0402: Exhaust Gas Recirculation (EGR) Flow Insufficient / Excessive Detected
System / Wiring Diagram
DTC Detecting Condition and Trouble Area (DTC P0401 / P0402)
DTC Confirmation Procedure (DTC P0401 / P0402)
WARNING:
- When performing a road test, select a place where there is no traffic or possibility of a traffic accident and be very careful during testing to avoid occurrence of an accident.
- Road test should be carried out with 2 persons, a driver and a tester, on a level road.
NOTE:
Check to make sure that the following conditions are satisfied when using this DTC confirmation procedure.
- Intake air temp.: Between -10 °C and 70 °C (14 °F and 158 °F)
- Altitude (barometric pressure): 2020 m, 6650 ft or less (540 mmHg, 72 kPa or more)
1) With ignition switch turned OFF, connect scan tool.
2) Turn ON ignition switch and clear DTC using scan tool.
3) Start engine and warm up to normal operating temperature.
4) Drive vehicle at 40 mph (60 km/h) or more (engine speed; 2000 - 3000 r/min.).
5) Keep the vehicle speed for 10 min. (Throttle valve opening is kept constant in this step.)
6) Stop vehicle.
7) Check if DTC / pending DTC exists using scan tool. If not, check if EGR system monitoring test has completed using scan tool. If not in both of the checks (i.e., no DTC / pending DTC and EGR system monitoring test not completed), check vehicle conditions (environmental) and repeat Steps 3 through 6.
DTC Troubleshooting
1.
Was "Engine System Check" performed?
YES
Go to Step 2.
NO
Go to Engine System Check Engine System Check.
2.
Do you have SUZUKI scan tool?
YES
Go to Step 3.
NO
Go to Step 5.
3. EGR valve operation check.
With ignition switch turned OFF, install SUZUKI scan tool.
Check EGR system referring to Testing and Inspection EGR System Inspection (Using SUZUKI Scan Tool).
Is it in good condition?
YES
Go to Step 4.
NO
Go to Step 5.
4. MAP sensor check.
Check MAP sensor for performance referring to Testing and Inspection Manifold Absolute Pressure (MAP) Sensor Inspection.
Is check result satisfactory?
YES
Intermittent trouble or faulty ECM
Check for intermittent referring to Intermittent and Poor Connection Inspection.
NO
Repair or replace.
5. EGR valve power supply circuit check.
With ignition switch turned OFF, disconnect EGR valve coupler.
With ignition switch turned ON, check voltage between "BLK/RED" wire terminal of EGR valve coupler and engine ground.
Is each voltage 10 - 14 V?
YES
Go to Step 6.
NO
Faulty "RED/BLK" wire.
6. Check wire circuit.
Measure voltage between engine ground and each "GRY", "GRY/WHT", "GRY/YEL", "BRN/WHT" wire terminal.
Is each voltage 0 V?
YES
Go to Step 6.
NO
Some wire shorted to other circuits.
If wires are OK, substitute a known-good ECM and recheck.
7. Check wire circuit.
With ignition switch turned OFF, check that there are insulating between engine ground and each "GRY", "GRY/WHT", "GRY/YEL", "BRN/WHT" wire terminal.
Are there insulating.
YES
Go to Step 7.
NO
Some wire shorted to ground circuit.
If wires are OK, substitute a known-good ECM and recheck.
8. EGR valve stepping motor coil circuit check.
With ignition switch turned OFF, connect EGR valve coupler and disconnect ECM couplers.
Check resistance between "G04-8 (or 23) and "C46-3", "C46-13", "C46-14", "C46-15".
Is each resistance 20 - 24 ohms at 20 °C, 68 °F.
YES
Go to Step 7.
NO
Faulty "GRY", "GRY/WHT", "GRY/YEL", "BRN/WHT" wire or EGR valve.
9. Check wire circuit.
Measure voltage between engine ground and each "GRY", "GRY/WHT", "GRY/YEL", "BRN/WHT" wire terminal.
Is each voltage 10 - 14 V?
YES
Some wire in high resistance circuit.
If wires are good condition, faulty EGR valve.
NO
Some wire open circuit.
If wires are good condition, faulty EGR valve.
10. MAP sensor check:
Check MAP sensor for performance referring to Testing and Inspection Manifold Absolute Pressure (MAP) Sensor Inspection.
Is check result satisfactory?
YES
EGR passage clogged or EGR valve malfunction, If all results are OK, intermittent trouble or faulty ECM.
Check for intermittent referring to Intermittent and Poor Connection Inspection.
NO
Repair or replace.