Suzuki Grand Vitara JB416 / JB420. Manual - part 47

1A-137 Engine General Information and Diagnosis: 

DTC P0403: Exhaust Gas Recirculation Control Circuit

S5JB0A1104043

Wiring Diagram
Refer to “DTC P0401 / P0402: Exhaust Gas Recirculation Flow Insufficient Detected / Excessive Detected”.

DTC Detecting Condition and Trouble Area

DTC Confirmation Procedure

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 by 2 persons, a driver and a tester, on a level road.

 

1) With ignition switch turned OFF, connect scan tool to DLC.
2) Turn ON ignition switch and clear DTC using scan tool.
3) Start engine and warm it up to normal operating temperature.
4) Drive vehicle in 2000 – 3500 rpm of engine speed.
5) Keep above vehicle speed for 1 min. (Throttle valve opening is kept constant in this step.)
6) Stop vehicle and check DTC and pending DTC.

DTC Troubleshooting

NOTE
Before this trouble shooting is performed, read the precautions for DTC troubleshooting referring to 
“Precautions For DTC Troubleshooting”.

 

DTC detecting condition

Trouble area

EGR valve output voltage is different from output command with more 
than one pole out of 4 poles.
(1 driving cycle detection logic)

• EGR valve circuit open
• EGR  valve
• ECM

Step

Action

Yes

No

1

Was “Engine and Emission Control System Check” 
performed?

Go to Step 2.

Go to “Engine and 
Emission Control 
System Check”.

2

EGR valve power supply circuit check
1) With ignition switch turned OFF, disconnect EGR valve 

connector.

2) With ignition switch turned ON, measure voltage 

between “BLU/BLK” wire terminal of EGR valve 
connector and vehicle body ground.

Is check voltage 10 – 14 V?

Go to Step 3.

“BLU/BLK” wire is open 
circuit.

3

Wire circuit check
1) Disconnect connectors from ECM with ignition switch 

turned OFF.

2) Turn ON ignition switch.
3) Measure voltage between engine ground and each 

“YEL/BLK”, “YEL/RED”, “YEL/GRN”, “YEL” wire 
terminals of EGR valve connector.

Is each voltage 0 V?

Go to Step 4.

Faulty wire(s) are 
shorted to other circuit.
If wires are OK, 
substitute a known-
good ECM and recheck.

Engine General Information and Diagnosis:  1A-138

4

Wire circuit check
1) With ignition switch turned OFF, measure resistance 

between engine ground and each “YEL/BLK”, “YEL/
RED”, “YEL/GRN”, “YEL” wire terminals of EGR valve 
connector.

Is resistance infinity?

Go to Step 5.

Faulty wire(s) are 
shorted to ground 
circuit.
If wires are OK, 
substitute a known-
good ECM and recheck.

5

Short circuit check for EGR valve control circuit
1) With ignition turned OFF, measure resistance between 

each EGR valve control circuit wire (“YEL/BLK”, “YEL/
RED”, “YEL/GRN” and “YEL” wire) and each EGR valve 
control circuit wire.

Is each resistance infinity?

Go to Step 6.

Faulty wire(s) are short 
circuit.

6

EGR valve stepper motor coil circuit check
1) With ignition switch turned OFF, connect EGR valve 

connector.

2) Measure resistance between “E23-1/16” and each “C37-

3”, “C37-4”, “C37-5”, “C37-6” terminals of ECM 
connector.

Is each resistance 20 – 31 

Ω

 at 20 

°

C, 68 

°

F?

Faulty ECM. Substitute 
a known-good ECM and 
recheck.

Go to Step 7.

7

EGR valve check
1) Check EGR valve resistance referring to “EGR Valve 

Inspection in Section 1B”.

Is resistance within specified value?

Faulty wire(s) are open 
or high resistance 
circuit. If wires are OK, 
substitute a known-
good ECM and recheck.

Faulty EGR valve.

Step

Action

Yes

No

1A-139 Engine General Information and Diagnosis: 

DTC P0420: Catalyst System Efficiency below Threshold

S5JB0A1104044

System and Wiring Diagram

Circuit Description
ECM monitors oxygen concentration in the exhaust gas which has passed the warm up three way catalytic converter 
by HO2S-2. When the catalyst is functioning properly, the variation cycle of HO2S-2 output voltage (oxygen 
concentration) is slower than that of A/F sensor output signal because of the amount of oxygen in the exhaust gas 
which has been stored in warm up three way catalytic converter.

A/F Sensor Description
Refer to “A/F Sensor Description”.

DTC Detecting Condition and Trouble Area

DTC Confirmation Procedure

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 by 2 persons, a driver and a tester, on a level road.

 

NOTE
Check to make sure that following conditions are satisfied when using this “DTC Confirmation 
Procedure”.
• Intake air temperature at engine start: –10 

°C (14 °F) to 80 °C (176 °F)

• Intake air temperature: –10 

°C (14 °F) to 70 °C (158 °F)

• Engine coolant temperature: 70 

°C (158 °F) to 150 °C (302 °F)

• Altitude (barometric pressure): 2400 m, 8000 ft or less (560 mmHg, 75 kPa or more)

 

C37-11

C37-38 

C37-57

WHT

BRN

1

3

2

4

5 V

YEL

BLU

WHT

BLU WHT

C37-37

BLK

5

5 V

I5JB0A110053-02

1. A/F sensor

3. Warm up three way catalytic converter

5. ECM

2. HO2S-2

4. Three way catalytic converter

DTC detecting condition

Trouble area

Ratio of integrated value of HO2S-2 output variation per integrated 
value of A/F sensor output variation is more than specification while 
vehicle is running constant speed and low engine load after warmed 
up.
(*2 driving cycle detection logic, monitoring once / 1 driving) 

• Exhaust gas leak
• Warm up three way catalytic converter 

malfunction

• HO2S-2 malfunction
• A/F sensor malfunction

Engine General Information and Diagnosis:  1A-140

1) Connect scan tool to DLC with ignition switch turned OFF.
2) Turn ON ignition switch and clear DTC using scan tool.
3) Increase vehicle speed to 50 – 60 mph, 80 – 100 km/h. (engine speed: 2500 – 3000 r/min.)
4) Keep above vehicle speed for 10 min. or more (Throttle valve opening is kept constant in this step).
5) Stop vehicle and check if DTC / pending DTC exists using scan tool. If not, check if catalyst monitoring test has 

been completed using scan tool. If not in both of above checks (i.e., no DTC / pending DTC and catalyst 
monitoring test not completed), check vehicle condition (environmental) and repeat Step 3) through 5).

DTC Troubleshooting

NOTE
Before this trouble shooting is performed, read the precautions for DTC troubleshooting referring to 
“Precautions For DTC Troubleshooting”.

 

Step

Action

Yes

No

1

Was “Engine and Emission Control System Check” 
performed?

Go to Step 2.

Go to “Engine and 
Emission Control 
System Check”.

2

Exhaust system visual check
1) Check exhaust system for leaks, damage and loose 

connection.

Is it in good condition?

Go to Step 3.

Repair or replace 
defective part.

3

HO2S-2 output voltage check
1) Check output voltage of HO2S-2 referring to “DTC 

P0137 / P0138: O2 Sensor (HO2S) Circuit Low Voltage / 
High Voltage (Sensor-2)”.

Is check result satisfactory?

Replace exhaust 
manifold (built in warm 
up three way catalytic 
converter) and exhaust 
center pipe (built in 
three way catalytic 
converter).

Check “BRN” and/or 
“YEL” wires for open 
and short, and 
connections for poor 
connection.
If wires and connections 
are OK, replace HO2S-
2.