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Hummer H2. Manual - part 1541

2. Disconnect the affected heated oxygen sensor

(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 6

Go to Step 5

Measure the voltage from the low 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?

2 V

Go to Step 7

Go to Step 8

Test the HO2S high signal circuit for a short to voltage.
Refer to Circuit Testing and Wiring Repairs in Wiring
Systems.Did you find and correct the condition?

IMPORTANT:

The sensor may be damaged if the circuit is shorted
to a voltage source.

Go to Step 17

Go to Step 14

Test the HO2S low signal circuit for a short to voltage.
Refer to Circuit Testing and Wiring Repairs in Wiring
Systems.
Did you find and correct the condition?

Go to Step 17

Go to Step 14

1. Connect a 3-amp fused jumper wire between the

high signal circuit of the HO2S harness connector
on the engine harness side and a good ground.

2. Observe the HO2S voltage parameter with a scan

tool.

Is the HO2S voltage parameter less than the specified
value?

100
mV

Go to Step 9

Go to Step 11

1. Remove the jumper wire from the previous step.

2. Connect a 3-amp fused jumper wire between the

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 12

Go to Step 10

Test the HO2S low signal circuit for an open or high

2004 Hummer H2

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

Hummer H2

resistance. Refer to Circuit Testing and Wiring
Repairs in Wiring Systems.
Did you find and correct the condition?

Go to Step 17

Go to Step 14

Test the HO2S high 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 17

Go to Step 14

1. The HO2S may be detecting a rich exhaust

condition or may be contaminated. Inspect for the
following conditions:

A silicon contaminated HO2S

Any water intrusion into the HO2S
connector

Engine oil contaminated with fuel

An evaporative emission (EVAP) canister
purge condition

An incorrect fuel pressure-Refer to Fuel
System Diagnosis .

Any rich fuel injectors-Refer to Fuel
Injector Balance Test with Tech 2 .

An inaccurate mass air flow (MAF) sensor-
Refer to Scan Tool Data List .

An air intake restriction or collapsed air
intake duct

2. Repair any of the above or similar engine

conditions as necessary.

Did you find and correct the condition?

NOTE:

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

Go to Step 17

Go to Step 13

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 17

Go to Step 15

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 17

Go to Step 16

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 P0140 OR P0160

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.
This diagnostic will only run once per ignition cycle. If the PCM detects that the HO2S voltage remains within
the bias voltage range, DTC P0140 sets for HO2S bank 1 sensor 2 or DTC P0160 sets for HO2S bank 2 sensor
2.

Conditions for Running the DTC

DTCs P0068, P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120,
P0141, P0161, 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 Loop Status is closed.

Replace the affected HO2S. Refer to Heated Oxygen
Sensor (HO2S) Replacement Bank 1 Sensor 2 or
Heated Oxygen Sensor (HO2S) Replacement Bank 2
Sensor 2 .
Did you complete the replacement?

Go to Step 17

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

Go to Step 17

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 18

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

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 410-490 mV for 150 seconds.

The TP Indicated Angle parameter changes more than 5 percent within 1 second, 6 times.

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.

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 P0140 or P0160

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

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

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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