P0400

A : Diagnostic Trouble Code (DTC) P0400 Indicates Exhaust Gas Recirculation (EGR) System Flow Malfunction.

A1 : CHECK EGR VALVE FOR CORRECT FITMENT TO INTAKE MANIFOLD
1. Check the EGR valve retaining bolts for correct torque.

Was the EGR valve fitted correctly?

Yes
Goto A3

No
Goto A2

A2 : CHECK EXHAUST GAS RECIRCULATION (EGR) VALVE TO MANIFOLD/INTAKE ELBOW GASKET FOR CORRECT SEAL
1. Visually inspect the gasket for external damage.

Is the gasket damaged?

Yes
INSTALL a new gasket, make sure valve is seated correctly and retaining bolts installed to the correct torque. CLEAR DTC. To validate fix drive vehicle between 30 mph (48 kph) and 40 mph (64 kph). Allow vehicle to idle for 2 minutes.

No
Goto A3

A3 : CHECK FOR EXHAUST MANIFOLD TO EGR VALVE TUBE FOR DAMAGE or BLOCKAGES
1. Visually inspect the exhaust manifold to EGR valve tube.

Is the tube damaged or blocked?

Yes
If the tube is damaged INSTALL a new tube. CLEAR the DTC. To validate fix drive vehicle between 30 mph (48 kph) and 40 mph (64 kph). Allow vehicle to idle for 2 minutes. If the tube is blocked, unblock the tube. CLEAR DTC. TEST the system for normal operation.

No
Goto A4

A4 : CHECK FOR POWER SUPPLY TO EGR VALVE
1. Disconnect EGR valve electrical connector PI 15
2. TURN ignition switch to the ON position
3. MEASURE the voltage at PI 15 pin 2 (GU)

Is the voltage less than 10 volts

Yes
Goto A5

No
Goto A5

A5 : CHECK FUSE 37 IN THE FRONT POWER DISTRIBUTION BOX (FPDB)
1. Check the fuse.

Is the fuse ok?

Yes
Goto A7

No
Goto A8

A6 : CHECK HARNESS BETWEEN FPDB AND EGR FOR SHORT TO GROUND
1. Disconnect the EGR valve electrical connector PI 15.
2. CHECK the resistance between PI 15 pin 2 (GU) and ground.

Is the resistance less than 10,000 Ohms?

Yes
REPAIR the circuit between the EGR valve and FPDB. INSTALL a new fuse. CLEAR DTC. To validate fix drive vehicle between 30 mph (48 kph) and 40 mph (64 kph). Allow vehicle to idle for 2 minutes.

No
INSTALL a new fuse. CLEAR DTC. To validate fix drive vehicle between 30 mph (48 kph) and 40 mph (64 kph). Allow vehicle to idle for 2 minutes.

A7 : CHECK FOR BATTERY VOLTAGE AT FPDB
1. CHECK for voltage at FPDB electrical connector FH 32 pin 43 (GU).

Is the voltage less than 10 volts?

Yes
REPAIR the circuit between FPDB electrical connector FH 32 pin 43 (GU) and FPDB relay 5.

No
REPAIR the circuit between FPDB electrical connector FH 32 pin 43 (GU) and EGR valve electrical connector PI 15 pin 2 (GU). CLEAR DTC. To validate fix drive vehicle between 30 mph (48 kph) and 40 mph (64 kph). Allow vehicle to idle for 2 minutes.

A8 : CHECK FOR POWER SUPPLY TO EGR VALVE
1. Disconnect EGR valve electrical connector PI 15
2. MEASURE the voltage at PI 15 pin 5 (GU)

Is the voltage less than 10 volts?

Yes
REPAIR the circuit between PI 15 pin 5 (GU) and splice PIS 15. CLEAR DTC. TEST the system for normal operation.

No
INSTALL a new EGR valve. CLEAR DTC. To validate fix drive vehicle between 30 mph (48 kph) and 40 mph (64 kph). Allow vehicle to idle for 2 minutes.