Isuzu KB P190. Service manual - part 582

6E–158

ENGINE DRIVEABILITY AND EMISSIONS

12

Check for the following conditions. 

• Objects blocking the IAC valve. 

• Objects blocking the throttle valve. 

• Vacuum leaking at throttle body. 
If a problem is found, repair as necessary. 
Was the problem found?

—

Verify repair

Go to Step 13

13

Check for injector for the affected bank. 
Refer to “Injector Coil Test & Injector Balance Test
Procedure” 6E-98 page. 
Was the injector operation correct?

—

Go  to  Step 14

Refer to Injector 

Coil Test & 

Injector 

Balance Test 

Procedure

14

Check for fuel pressure. 
Refer to “Fuel System Diagnosis” 6E-108 page. 
Was the fuel pressure correct? 

—

Go to Step 15

Refer to Fuel 

System 

Diagnosis

15

Replace the O

2

 sensor. 

Was the problem solved?

—

Verify repair

Go to Step 16

16

Is the ECM programmed with the latest software
release? 
If not, download the latest software to the ECM using
the “SPS (Service Programming System)”. 
Was the problem solved?

—

Verify repair

Go to Step 17

17

Replace the ECM. 
Is the action complete? 
IMPORTANT:  The replacement ECM must be
programmed. Refer to section of the Service
Programming System (SPS) in this manual. 
Following ECM programming, the immobilizer system
(if equipped) must be linked to the ECM. Refer to
section 11 “Immobilizer System-ECM replacement” for
the ECM/Immobilizer linking procedure.

—

Verify repair

—

Step

Action

Value(S)

Yes

No

ENGINE DRIVEABILITY AND EMISSIONS

6E–159

DIAGNOSTIC TROUBLE CODE (DTC) P0134 O

2

 SENSOR NO ACTIVITY 

DEFECTED (BANK 1 SENSOR 1)

Condition for setting the DTC and action taken when the DTC sets

Circuit Description

The engine control module (ECM) supplies a bias
voltage of about 450 mV between the heated oxygen
sensor (HO2S) high and low circuits. The oxygen
sensor varies the voltage within a range of about 1000
mV when the exhaust is rich, down through about 10
mV when exhaust is lean. The ECM constantly monitors
the HO2S signal during “Closed Loop” operation and

compensates for a rich or lean condition by decreasing
or increasing injector pulse width as necessary. If the
Bank 1 HO2S 1 voltage remains at or near the 450 mV
bias for an extended period of time, Diagnostic Trouble
Code P0134 will be set, indicating an open sensor
signal or sensor low circuit.

Code

Type

DTC Name

DTC Setting Condition

Fail-Safe (Back Up)

P0134

A

O

2

 Sensor Circuit No Activity Detected 

(Bank 1 Sensor 1)

1.  No DTC relating to MAP sensor, TPS, 

EVAP purge, ECT sensor, CKP sensor, 
VSS, injector control circuit and ignition 
control circuit. 

2. Engine coolant temperature is more than 

60 deg.C. 

3. Engine run time is longer than 40 seconds. 
4. Mass air flow is more than 7g/s. 
5. O

2

 sensor bank 1 output voltage is 

between 300mV and 600mV.

“Open Loop” fuel control.

6E–160

ENGINE DRIVEABILITY AND EMISSIONS

Diagnostic Aids

Check for the following conditions:

• Poor connection or damaged harness - Inspect the

harness connectors for backed-out terminals,
improper mating, broken locks, improperly formed or
damaged terminals, poor terminal-to-wire connection,
and damaged harness.

Diagnostic Trouble Code (DTC) P0134 

O

2

 Sensor Circuit No Activity Detected (Bank 1 Sensor 1)

Step

Action

Value(s)

Yes

No

1

Was the “On-Board Diagnostic (OBD) System Check”
performed?

—

Go  to Step 2

Go to On Board 

Diagnostic 

(OBD) System 

Check

2

1. Connect the Tech 2. 

2. Review and record the failure information. 

3. Select “F0: Read DTC Infor By Priority” in “F0:

Diagnostic Trouble Code”. 

Is the DTC P0134 stored as “Present Failure”?

—

Go to Step 3

Refer to 

Diagnostic Aids 

and Go to Step 

3

3

1. Using the Tech2, ignition “On” and engine “Off”. 

2. Select “Clear DTC Information” with the Tech2 and

clear the DTC information. 

3. Operate the vehicle and monitor the “F5: Failed

This Ignition” in “F2: DTC Information”.

Was the DTC P0134 stored in this ignition cycle?

—

Go to Step 4

Refer to 

Diagnostic Aids 

and Go to Step 

4

4

Check for poor/faulty connection at the O

2

 sensor or

ECM connector. If a poor/faulty connection is found,
repair as necessary. 
Was the problem found?

—

Verify repair

Go to Step 5

5

Using the DVM and check the O

2

 sensor circuit.

1.  Ignition “On”, engine “Off”. 

2. Disconnect the O

2

 sensor connector. 

3. Check the circuit for open circuit. 

Was the DVM indicated specified value?

Approximatly 

450mV

Go to Step 7

Go to Step 6

C56(J2)

E77

31

21

6

V

2

1

E77

ENGINE DRIVEABILITY AND EMISSIONS

6E–161

6

Using the DVM and check the O

2

 sensor circuit.

Breaker box is available: 

1. Ignition “Off”, engine “Off”. 

2. Install the breaker box as type A. (ECM

disconnected) Refer to 6E-88 page.

3. Disconnect the O

2

 sensor. 

4. Check the circuit for open circuit. 

Was the problem found?

Breaker box is not available: 

1. Ignition “Off”, engine “Off”. 

2. Disconnect the O

2

 sensor connector and ECM

connector. 

3. Check the circuit for open circuit. 

Was the problem found?

—

Repair faulty 

harness and 

verify repair

Go to Step 13

7

1.  Using the Tech 2, ignition “On” and engine “On”. 

2. Monitor the “Manifold Absolute Pressure” in the

data display.                                

Does the Tech 2 indicate correct “Manifold Absolute
Pressure” in accordance with engine speed or
acceleration?   

—

Go to Step 9

Go to Step 8

8

Remove the MAP sensor and check for the following
conditions. 

• Objects blocking the air cleaner. 

• Objects blocking the MAP sensor. 

• Objects blocking the throttle valve. 

• Vacuum leaking at intake duct. 

• Vacuum leaking at throttle body. 
If a problem is found, repair as necessary. 
Was the problem found?

—

Verify repair

Go to Step 9

9

1. Using the Tech 2, ignition “On” and engine “On”. 

2. Select the “Miscellaneous Test” and perform the

“IAC Control” in the “IAC System”. 

3. Operate the Tech 2 in accordance with procedure. 

Was the engine speed changed, when the IAC valve
is operating step by step?

—

Go to Step 11

Go to Step 10

Step

Action

Value(s)

Yes

No

J2-6

J2-21

Breaker Box

E-77

2

1

Ω

Ω

1

2

21

6

C56(J2)

E77