Hummer H2. Manual - part 1639

DTC P0137 OR P0157

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 an HO2S voltage that stays below a specified value, DTC P0137 sets for HO2S bank 1
sensor 2 or DTC P0157 sets for HO2S bank 2 sensor 2.

Conditions for Running the DTC

Lean Test Enable:

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 Loop Status parameter is closed.

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

The Fuel Tank Level Remaining parameter is more than 10 percent.

The TP Indicated Angle parameter is between 3-70 percent more than the value observed at idle.

Power Enrichment Test Enable:

The Loop Status parameter is closed.

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

The Fuel Tank Level Remaining parameter is more than 10 percent.

The Engine Run Time parameter is more than 30 seconds.

Did the DTC fail this ignition?

Go to Step 2

Go to Step 21

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 Power Enrichment parameter is active for more than 2 seconds.

Conditions for Setting the DTC

Lean Test

The PCM detects that the affected HO2S voltage parameter is less than 80 mV for 200 seconds.

Power Enrichment Test

The PCM detects that the affected HO2S voltage parameter is less than 420 mV for 10 seconds.

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 numbers below refer to the step numbers on the diagnostic table.

2: If the voltage does not change more than the specified value, the condition is present.

DTC P0137 or P0157

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

2004 Hummer H2

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

Hummer H2

Did you perform the Diagnostic System Check-Engine
Controls?

Go to Step 2

Go to Diagnostic

System Check -

Engine Controls

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. While observing the affected HO2S voltage

parameter with a scan tool, quickly cycle the
throttle from closed throttle to wide open throttle,
3 times.

Did the HO2S voltage parameter change more than the
specified value?

IMPORTANT:

With the engine running, observe the HO2S Bank 1
Sensor 1 and HO2S Bank 2 Sensor 1 voltage
parameters with a scan tool. The voltage should vary
from below 300 mV to above 600 mV. If the voltage is
not varying, refer to DTC P0132 or P0152 .

200
mV

Go to Step 3

Go to Step 4

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 4

Go to

Intermittent

Conditions

1. Turn OFF the ignition.

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 less than the specified
value?

100
mV

Go to Step 6

Go to Step 5

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 8

2004 Hummer H2

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

Hummer H2

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

Go to Step 20

Go to Step 9

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 20

Go to Step 17

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 10

Go to Step 11

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

Go to Step 20

Go to Step 17

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 20

Go to Step 17

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 12

Go to Step 14

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 15

Go to Step 13

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

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