Suzuki Grand Vitara JB627. Manual - part 29

1A-65 Engine General Information and Diagnosis: 

DTC P0037 / P0038: HO2S Heater Control Circuit Low / High (Sensor-2, Bank-1)

S6JB0B1104015

System and Wiring Diagram

NOTE
When DTC P0031, P0037, P0051 and P0057 are indicated together, it is possible that HO2S heater relay 
circuit wire is open or short to ground.

 

DTC Detecting Condition and Trouble Area

9

A/F sensor heater check
1) Check heater resistance of A/F sensor (bank-1) referring 

to “Air Fuel Ratio (A/F) Sensor On-Vehicle Inspection in 
Section 1C”.

Is A/F sensor heater in good condition?

Substitute a known 
good ECM and recheck.

Replace A/F sensor 
(bank-1).

Step

Action

Yes

No

4

3

9

RED

GRN

PNK

BLK

C37-2  

C37-3  

C37-67  

6

2

7

10

BLK

BLU

WHT

BLK/RED

GRY/GRN

1

8

5

5V  

BLK/WHT

BLK

PNK

GRN

C37-1  

BLK/RED

1

3 2

4

5

6

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9

1110

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a

b

I6JB01110002-01

a. Power supply circuit of HO2S (bank-1) heater

2. Shield wire

5. IG COIL fuse

8. To A/F sensor (bank-1 and -2), HO2S (bank -2)

b. Control circuit of HO2S (bank-1) heater

3. Ignition Switch

6. HO2S (bank-1)

9. ECM

1. HO2S heater relay

4. O2 HTR fuse

7. HO2S heater

10. To other sensors

DTC detecting condition

Trouble area

DTC P0037 HO2S Heater Control Circuit Low (Sensor-2, Bank-1):
Circuit current of HO2S (bank-1) heater is lower than specification 
(0.16 – 0.28 A depending on battery voltage) for more than 1 sec. 
continuously while control duty of HO2S sensor heater is ON with 
engine running.
(2 driving cycle detection logic)
DTC P0038 HO2S Heater Control Circuit High (Sensor-2, Bank-1):
Circuit current of HO2S sensor (bank-1) heater is higher than 5 A at ON 
duty pulse or 0.2 A at OFF duty pulse for more than 1 sec. continuously 
while control duty of HO2S sensor heater is ON with engine running.
(2 driving cycle detection logic)

• HO2S heater circuit
• HO2S
• ECM

Engine General Information and Diagnosis:  1A-66

DTC Confirmation Procedure

1) With ignition switch turned OFF, connect scan tool to DLC.
2) Turn ON ignition switch and clear DTC.
3) Start engine and warm up to normal operating temperature.
4) Run engine at idle speed for 1 min. or more.
5) 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”.

 

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

A/F sensor DTC check

Are there DTC P0031 and/or P0051?

Go to applicable DTC 
flow referring to “DTC 
P0031 / P0032: HO2S 
Heater Control Circuit 
Low / High (Sensor-1, 
Bank-1)” and/or “DTC 
P0051 / P0052: HO2S 
Heater Control Circuit 
Low / High (Sensor-1, 
Bank-2)”.

Go to Step 3.

3

HO2S heater relay and its circuit check
1) Disconnect connector from HO2S (bank-1) with ignition 

switch turned OFF.

2) Check for proper terminal connection to HO2S (bank-1) 

connector.

3) If connections are OK, check that HO2S (bank-1) heater 

control circuit is as follows.
• Circuit voltage between “Power supply circuit of HO2S 

(bank-1) heater” and vehicle body ground is battery 
voltage with ignition switch turned ON.

Is it in good condition?

Go to Step 4

Repair or replace 
defective wiring 
harness.

4

HO2S heater circuit check
1) Check that HO2S (bank-1) heater control circuit is as 

follows.
• Circuit voltage between “Control circuit of HO2S 

(bank-1) heater” and vehicle body ground is 0 V with 
ignition switch turned ON.

Is it good condition?

Go to Step 5.

Repair or replace 
defective wiring 
harness.

1A-67 Engine General Information and Diagnosis: 

5

HO2S heater circuit check
1) Disconnect connectors form ECM and check for proper 

terminal connection to ECM connector.

2) If connections are OK, check that HO2S (bank-1) heater 

circuit is as follows.
• Insulation resistance of wire harness is infinity 

between “Control circuit of HO2S (bank-1) heater” 
terminal and each other terminal at HO2S (bank-1) 
connector.

• Wiring harness resistance of “Control circuit of HO2S 

(bank-1) heater” is less than 1 

Ω.

• Insulation resistance between “Control circuit of 

HO2S (bank-1) heater” and vehicle body ground is 
infinity.

Is it in good condition?

Go to Step 6.

Repair or replace 
defective wiring 
harness.

6

HO2S heater check
1) Check heater resistance of HO2S (bank-1) referring to 

“Heated Oxygen Sensor (HO2S-2) Heater On-Vehicle 
Inspection (If Equipped) in Section 1C”.

Is HO2S (bank-1) heater in good condition?

Substitute a known 
good ECM and recheck.

Replace HO2S (bank-
1).

Step

Action

Yes

No

Engine General Information and Diagnosis:  1A-68

DTC P0051 / P0052: HO2S Heater Control Circuit Low / High (Sensor-1, Bank-2)

S6JB0B1104016

System and Wiring Diagram

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

NOTE
When DTC P0031, P0037, P0051 and P0057 are indicated together, it is possible that HO2S heater relay 
circuit wire is open or short to ground.
When DTC P0032, P0052 are indicated together, it is possible that “A/F sensor heater ground circuit is 
open or high resistance.

 

DTC Detecting Condition and Trouble Area

4

3

9

PNK

6

2

1

8

5

BLK/WHT

BLK

PNK

GRN

C37-35

C37-78

C37-38

C37-37

BLK

BLK

BLU

WHT

C37-36

C37-79

BRN

YEL

BLU/YEL

BLU/RED

PNK/BLU

BLK/YEL

10

7

11

5 V

5 V

1

3 2

4

5

6

7

8

9

1110

12

13

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32

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2

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5

6

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e

f

d

a

b

c

I6JB01110003-01

a. Power supply circuit of A/F sensor (bank-2) heater

f. Power supply circuit of 

HO2S heater relay

5. IG COIL fuse

10. Adjusting resistor (if 

equipped)

b. Control circuit of A/F sensor (bank-2) heater

1. HO2S heater relay

6. A/F sensor

11. A/F sensor element

c. Ground circuit of A/F sensor (bank-2) heater

2. Shield wire

7. A/F sensor heater

d. Ground circuit of HO2S heater relay coil

3. Ignition Switch

8. To A/F sensor (bank-1), HO2S 

(bank-1 and -2) (if equipped)

e. Power supply circuit of HO2S heater relay coil

4. O2 HTR fuse

9. ECM

 

DTC detecting condition

Trouble area

DTC P0051 HO2S Heater Control Circuit Low (Sensor-1, Bank-2):
Circuit current of A/F sensor (bank-2) heater is lower than 0.8 A for 
more than 4 sec. continuously while control duty ratio of A/F sensor 
heater is more than 22% with engine running.
(2 driving cycle detection logic)
DTC P0052 HO2S Heater Control Circuit High (Sensor-1, Bank-2):
Circuit current of A/F sensor (bank-2) heater is higher than 10.5 A at 
ON duty pulse or 0.8 A at OFF duty pulse for more than 4 sec. 
continuously while control duty ratio of A/F sensor heater is more than 
22% with engine running.
(2 driving cycle detection logic)

• A/F sensor heater circuit
• A/F sensor
• ECM