Hummer H2. Manual - part 1535

high signal circuit of the HO2S harness
connector on the engine harness side and the low
signal circuit of the HO2S harness connector on
the engine harness side.

3. Observe the HO2S voltage parameter with a scan

tool.

Is the HO2S voltage parameter less than the specified
value?

100
mV

Go to Step 8

Go to Step 7

Test the HO2S low signal circuit for an open or high
resistance. Refer to Circuit Testing and Wiring
Repairs in Wiring Systems.
Did you find and correct the condition?

Go to Step 12

Go to Step 9

Test for shorted terminals and for poor connections at
the HO2S. Refer to Testing for Intermittent
Conditions and Poor Connections and Connector
Repairs in Wiring Systems.
Did you find and correct the condition?

Go to Step 12

Go to Step 10

Test for shorted terminals and for poor connections at
the powertrain control module (PCM). Refer to Testing
for Intermittent Conditions and Poor Connections
and Connector Repairs in Wiring Systems.
Did you find and correct the condition?

Go to Step 12

Go to Step 11

A silicon contaminated HO2S

Fuel contamination-Refer to
Alcohol/Contaminants-in-Fuel Diagnosis
(without Special Tool and E85) or
Alcohol/Contaminants-in-Fuel Diagnosis (with
Special Tool) .

Engine oil consumption-Refer to Oil
Consumption Diagnosis in Engine Mechanical.

Engine coolant consumption-Refer to Loss of
Coolant in Engine Cooling.

Replace the affected HO2S. Refer to Heated Oxygen
Sensor (HO2S) Replacement Bank 1 Sensor 1 or

NOTE:

Refer to Silicon Contamination of Heated Oxygen
Sensors Notice in Cautions and Notices.

IMPORTANT:

The HO2S may be damaged due to contamination.
Prior to replacing the HO2S inspect for the following
sources of contamination:

2004 Hummer H2

2004 ENGINE PERFORMANCE Engine Controls Diagnosis (DTC P0068 To DTC P0141/P0161) - 4.8L, 5.3L, and 6.0L -

Hummer H2

DTC P0134 OR P0154

Circuit Description

Heated oxygen sensors (HO2S) are used for fuel control and post catalyst monitoring. Each HO2S compares the
oxygen content of the surrounding air with the oxygen content in the exhaust stream. The HO2S must reach
operating temperature to provide an accurate voltage signal. Heating elements inside the HO2S minimize the
time required for the sensors to reach operating temperature. The powertrain control module (PCM) supplies the
HO2S with a reference, or bias, voltage of about 450 mV. When the engine is first started the PCM operates in
open loop, ignoring the HO2S voltage signal. Once the HO2S reaches operating temperature and closed loop is
achieved, the HO2S generates a voltage within a range of 0-1,000 mV that fluctuates above and below bias
voltage. High HO2S voltage indicates a rich exhaust stream; low HO2S voltage indicates a lean exhaust stream.
If the PCM detects that the HO2S voltage remains within the bias voltage range, DTC P0134 sets for HO2S
bank 1 sensor 1, or DTC P0154 sets for HO2S bank 2 sensor 1.

Conditions for Running the DTC

DTCs P0068, P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120,
P0200, P0220, P0300, P0442, P0446, P0452, P0453, P0455, P0496, P1125, P1258, P1516, P2101,
P2108, P2135, U0107 are not set.

The Engine Run Time parameter is more than 300 seconds.

The Ignition 1 Signal parameter is between 10-18 volts.

Conditions for Setting the DTC

The PCM detects that the affected HO2S voltage parameter is between 350-550 mV for 60 seconds.

Heated Oxygen Sensor (HO2S) Replacement Bank 2
Sensor 1 .Did you complete the replacement?

Go to Step 12

Replace the PCM. Refer to Powertrain Control
Module (PCM) Replacement .
Did you complete the replacement?

Go to Step 12

1. Clear the DTCs with a scan tool.

2. Turn OFF the ignition for 30 seconds.

3. Start the engine.

4. Operate the vehicle within the Conditions for

Running the DTC. You may also operate the
vehicle within the conditions that you observed
from the Freeze Frame/Failure Records.

Did the DTC fail this ignition?

Go to Step 2

Go to Step 13

Observe the Capture Info with a scan tool.
Are there any DTCs that have not been diagnosed?

Go to

Diagnostic

Trouble Code

(DTC) List

System OK

2004 Hummer H2

2004 ENGINE PERFORMANCE Engine Controls Diagnosis (DTC P0068 To DTC P0141/P0161) - 4.8L, 5.3L, and 6.0L -

Hummer H2

Action Taken When the DTC Sets

The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition
cycle that the diagnostic runs and fails.

The control module records the operating conditions at the time the diagnostic fails. The first time the
diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic
reports a failure on the second consecutive ignition cycle, the control module records the operating
conditions at the time of the failure. The control module writes the operating conditions to the Freeze
Frame and updates the Failure Records.

The control module commands the Loop Status open.

Conditions for Clearing the MIL/DTC

The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles
that the diagnostic runs and does not fail.

A current DTC, Last Test Failed, clears when the diagnostic runs and passes.

A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other
emission related diagnostic.

Clear the MIL and the DTC with a scan tool.

Test Description

The number below refers to the step number on the diagnostic table.

3: If the voltage is varying above and below the specified value, the condition is not present.

DTC P0134 or P0154

Step

Action

Value

(s)

Yes

Schematic Reference: Engine Controls Schematics
Connector End View Reference: Engine Controls Connector End Views or Powertrain Control
Module (PCM) Connector End Views

Did you perform the Diagnostic System Check-
Engine Controls?

Go to Step 2

Go to Diagnostic

System Check -

Engine Controls

1. Turn ON the ignition, with the engine OFF.

2. Command the HO2S heaters ON with a scan

tool.

3. Wait 15 seconds to allow the HO2S heater

IMPORTANT:

Whenever the HO2S heaters are commanded ON
with a scan tool, they will continue to be pulsed
ON once per second until the ignition is turned
OFF for 30 seconds.

0.25-

3.125

2004 Hummer H2

2004 ENGINE PERFORMANCE Engine Controls Diagnosis (DTC P0068 To DTC P0141/P0161) - 4.8L, 5.3L, and 6.0L -

Hummer H2

current to stabilize.

4. Observe the affected HO2S heater current

parameter with a scan tool.

Is the HO2S heater current parameter within the
specified range?

Go to Step 3

Go to DTC P0135

or P0155

1. Start the engine.

2. Allow the engine to reach operating

temperature. Refer to Scan Tool Data List .

3. Operate the engine at 1,500 RPM for 30

seconds.

4. Observe the affected HO2S voltage parameter

with a scan tool.

Is the HO2S voltage parameter varying above and
below the specified range?

300-

600
mV

Go to Step 4

Go to Step 5

1. Observe the Freeze Frame/Failure Records for

this DTC.

2. Turn OFF the ignition for 30 seconds.

3. Start the engine.

4. Operate the vehicle within the Conditions for

Running the DTC. You may also operate the
vehicle within the conditions that you
observed from the Freeze Frame/Failure
Records.

Did the DTC fail this ignition?

Go to Step 5

Go to Intermittent

Conditions

1. Turn OFF the ignition.

2. Disconnect the affected HO2S.

3. Turn ON the ignition, with the engine OFF.

4. Observe the HO2S voltage parameter with a

scan tool.

Is the HO2S voltage parameter more than the
specified value?

800
mV

Go to Step 7

Go to Step 6

Measure the voltage from the high signal circuit of
the HO2S harness connector on the engine harness
side to a good ground with a DMM. Refer to Circuit
Testing in Wiring Systems.
Is the voltage more than the specified value?

0.2 V

Go to Step 8

Go to Step 9

IMPORTANT:

The sensor may be damaged if the circuit is

2004 Hummer H2

2004 ENGINE PERFORMANCE Engine Controls Diagnosis (DTC P0068 To DTC P0141/P0161) - 4.8L, 5.3L, and 6.0L -

Hummer H2

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