DTC P0135, P0141, P0155, or P0161. GMC Truck Yukon

For 1990-2009 cars only

Makes 🢒 GMC_Truck 🢒 2001 🢒 Yukon - 4WD 🢒 Engine 🢒 Engine Controls - 4.8L, 5.3L, and 6.0L 🢒 DTC P0135, P0141, P0155, or P0161

DTC P0135, P0141, P0155, or P0161 w/LR4 and LM7 w/ Delphi HO2S

Circuit Description

This diagnostic applies only to vehicles built with Delphi heated oxygen sensors. To identify the heated oxygen sensor refer to

Oxygen Sensor Identification (4.8L/5.3L/6.0L)


(1)	Delphi Sensor - Case Grounded
(2)	Denso Sensor - Isolated Grounded

in Engine Controls Component Views.

The powertrain control module (PCM) supplies a bias voltage of approximately 450 mV on the heated oxygen sensor (HO2S) signal high and low circuits. When you turn the ignition to the ON position, battery voltage is supplied to the HO2S heater. As the heater reaches the operating temperature, the HO2S voltage responds by changing from a bias voltage range to the normal operation. Typically, as the HO2S reaches the operating temperature, the HO2S voltage goes from a bias voltage to a voltage below 300 mV. Depending on the exhaust gas content, it is possible for the HO2S voltage to go above 450 mV.

The PCM runs the heater test only on a cold start (depends on the cumulative air flow) and only once an ignition cycle. When you start the engine the PCM monitors the HO2S voltage. When the HO2S voltage goes above or below the bias range threshold, the PCM determines how much time it took. If the PCM detects that the process took too much time for the HO2S to enter into normal operating range, a DTC sets. The time the process takes the HO2S to reach operating temperature is based on the amount of air that flows into the engine.

Conditions for Running the DTC

•

DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0131, P0132, P0134, P0137, P0138, P0140, P0151, P0152, P0154, P0157, P0158, P0160, P0200, P0300, P0401, P0404, P0405, P0410, P0440, P0442, P0446, P0452, P0453, P1120, P1125, P1220, P1221, P1258, P1404, P1415, P0416, P1514, P1515, P1516, P1517, or P1518 are not set.

•	The HO2S voltage is between 425-475 mV at engine start-up.

•	The intake air temperature (IAT) and the engine coolant temperature (ECT) are less than 50°C (122°F) and are within 8°C (14.5°F) of each other at engine start-up.

•	The ignition 1 signal is between 9-18 volts.

•	Intrusive tests are not in progress.

•	The scan tool output controls are not active.

•	The scan tool is disconnected.

Conditions for Setting the DTC

The HO2S voltage remains within 150 mV of the start-up voltage for a predetermined amount of time, based on ECT and air flow.

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.

Diagnostic Aids

Important: Remove any debris from the PCM connector surfaces before servicing the PCM. Inspect the PCM connector gaskets when diagnosing or replacing the PCM. Ensure that the gaskets are installed correctly. The gaskets prevent water intrusion into the PCM.

•

Using the Freeze Frame/Failure Records data may aid in locating an intermittent condition. If you cannot duplicate the DTC, the information included in the Freeze Frame/Failure Records can help determine how many miles since the DTC set. The Fail Counter and Pass Counter can also help determine how many ignition cycles the diagnostic reported a pass or a fail. Operate the vehicle within the same Freeze Frame conditions such as RPM, load, vehicle speed, and temperature that you observed. This will isolate when the DTC failed. For an intermittent condition, refer to Intermittent Conditions .

•	The heater diagnostic will only run on a cold start and run once per ignition cycle.

•	An oxygen supply inside the HO2S is necessary for proper operation. The HO2S wires provide the supply of oxygen. Inspect the HO2S wires and connections for breaks or contamination. Refer to Heated Oxygen Sensor Wiring Repairs in Wiring Systems.

Test Description

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

Allow the engine to cool before performing this test. If the sensor is at the operating temperature, the HO2S voltage will stay high or low. If the HO2S voltage stays between 300-700 mV this indicates the HO2S heater is inoperative.

If more than one HO2S DTC is set, this is a good indication that the HO2S fuse is open. Test all the related circuits going to all the heated oxygen sensors for a short to ground. If you cannot locate a shorted circuit, it may be necessary to disconnect each HO2S one at a time to locate a shorted sensor.

This step determines if an ignition positive voltage supply is available at the sensor.

This step determines if a ground is available at the sensor.

This step determines if the HO2S heater element is internally open.

Inspect the ignition positive voltage circuits at the underhood electrical center for poor connections.

Test the ground circuits for an open if more then one heater DTC sets.

Step

Action

Values

Yes

Schematic Reference: Engine Controls Schematics

Important: This diagnostic applies only to vehicles built with Delphi heated oxygen sensors. To identify the heated oxygen sensor, refer to

Oxygen Sensor Identification (4.8L/5.3L/6.0L)


(1)	Delphi Sensor - Case Grounded
(2)	Denso Sensor - Isolated Grounded

in Engine Controls Component Views.

Did you perform the Diagnostic System Check- Engine Controls?

Go to Step 2

Go to Diagnostic System Check - Engine Controls

Important: Allow the engine to cool for about one half hour before proceeding with this diagnosis.

Important: If DTC P0300 is set, diagnose that DTC first. Refer to Diagnostic Trouble Code (DTC) List

Turn OFF the ignition.
Install the scan tool.
Turn ON the ignition, with the engine OFF.
Monitor the HO2S signal voltage on the scan tool for 2 minutes.

Does the HO2S voltage go from a bias voltage to more than or less than the specified range?

300-700 mV

Go to Diagnostic Aids

Go to Step 3

Inspect the HO2S fuse for an open.

Is the HO2S fuse open?

Go to Step 11

Go to Step 4

Raise the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.
Disconnect the HO2S electrical connector.
Probe the ignition 1 voltage circuit at the PCM side of the HO2S electrical connector using a test lamp connected to a known good ground. Do not use the HO2S heater ground or the HO2S low signal circuits.

Does the test lamp illuminate?

Go to Step 5

Go to Step 7

Connect the test lamp between the HO2S ignition 1 voltage and the HO2S heater ground.

Does the test lamp illuminate?

Go to Step 6

Go to Step 8

Use a digital multimeter (DMM) in order to measure the resistance between the HO2S ignition 1 voltage and the HO2S heater ground at the HO2S pigtail.

Is the resistance within the specified range?

3.5-14.0 ohms

Go to Step 9

Go to Step 10

Repair the open in the HO2S ignition 1 voltage circuit to the HO2S. Refer to Heated Oxygen Sensor Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 12

Repair the open in the HO2S heater ground circuit. Refer to Heated Oxygen Sensor Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 12

Test for a poor connection at the HO2S harness terminals. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
If you find a poor connection, repair the terminal as necessary. Refer to Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 12

Go to Step 10

Replace the affected HO2S. Refer to the following procedures:

•	Heated Oxygen Sensor Replacement - Bank 1 Sensor 1

•	Heated Oxygen Sensor Replacement - Bank 1 Sensor 2

•	Heated Oxygen Sensor Replacement - Bank 2 Sensor 1

•	Heated Oxygen Sensor Replacement - Bank 2 Sensor 2

Did you complete the repair?

Go to Step 12

Locate and repair the short to ground in the HO2S ignition positive voltage circuit. Refer to Heated Oxygen Sensor Wiring Repairs in Wiring Systems.
Replace the faulty fuse.

Did you complete the repair?

Go to Step 12

Use the scan tool in order to clear the DTCs.
Disconnect the scan tool.
Turn OFF the ignition for 30 seconds.
Start the engine.
Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.
Install the scan tool.

Does the DTC run and pass?

Go to Step 13

Go to Step 2

With a scan tool, observe the stored information, Capture Info.

Does the scan tool display any DTCs that you have not diagnosed?

Go to Diagnostic Trouble Code (DTC) List

System OK

DTC P0135, P0141, P0155, or P0161 w/LR4 and LM7 w/ Denso HO2S

Circuit Description

This diagnostic applies only to vehicles built with Denso heated oxygen sensors. To identify the heated oxygen sensor refer to

Oxygen Sensor Identification (4.8L/5.3L/6.0L)


(1)	Delphi Sensor - Case Grounded
(2)	Denso Sensor - Isolated Grounded

in Engine Controls Component Views.

Conditions for Running the DTC

•

•	The HO2S voltage is between 425-475 mV at engine start-up.

•	The intake air temperature (IAT) and the engine coolant temperature (ECT) are less than 50°C (122°F) and are within 8°C (14.5°F) of each other at engine start-up.

•	The ignition 1 signal is between 9-18 volts.

•	Intrusive tests are not in progress.

•	The scan tool output controls are not active.

•	The scan tool is disconnected.

Conditions for Setting the DTC

The HO2S voltage remains within 150 mV of the start-up voltage for a predetermined amount of time, based on ECT and air flow.

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.

•

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.

Diagnostic Aids

Important: Never solder the HO2S wires. For proper wire and connection repairs, refer to Wiring Repairs or to Connector Repairs in Wiring Systems.

An intermittent may be caused by any of the following conditions:

•	A poor connection

•	Rubbed through wire insulation

•	A broken wire inside the insulation

Thoroughly check any circuitry that is suspected of causing the intermittent complaint. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

If a repair is necessary, then refer to Wiring Repairs or Connector Repairs in Wiring Systems.

Test Description

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

As the heater warms the oxygen sensor to operating temperature, the HO2S will output a voltage in relation to the amount of oxygen in the exhaust. With the ignition ON and the engine OFF, the exhaust usually contains a high oxygen content. With the engine OFF, the HO2S voltage will usually decrease from the initial voltage due to the high oxygen content.

This step checks for proper HO2S heater ignition positive voltage and ground supply.

This step checks for proper PCM and signal circuit operation.

Step

Action

Values

Yes

Schematic Reference: Engine Controls Schematics

Important: This diagnostic applies only to vehicles built with Denso heated oxygen sensors. To identify the heated oxygen sensor, refer to

Oxygen Sensor Identification (4.8L/5.3L/6.0L)


(1)	Delphi Sensor - Case Grounded
(2)	Denso Sensor - Isolated Grounded

in Engine Controls Component Views.

Did you perform the Diagnostic System Check-Engine Controls?

Go to Step 2

Go to Diagnostic System Check - Engine Controls

Important: The HO2S must be cool before proceeding with the diagnosis. The ignition must remain OFF for at least one half hour before proceeding with diagnosis.

Important: If DTC P0300 is set, diagnose that DTC first. Refer to Diagnostic Trouble Code (DTC) List

Connect the scan tool.
Setup the scan tool with the correct VIN information prior to turning the ignition ON.
Turn ON the ignition, leaving the engine OFF.
As quickly as possible, observe and record the HO2S voltage for the sensor that applies to this DTC.
Monitor the HO2S voltage for 2 minutes.

Does the voltage increase or decrease from the initial voltage by at least the specified value?

150 mV

Go to Step 3

Go to Step 4

The condition that set this DTC is not present. This DTC may have been set by one of the following conditions:

•	An intermittently open or high resistance HO2S high signal circuit or low reference circuit

•	An intermittently open or high resistance HO2S heater ignition 1 voltage or ground circuit

•	A poor HO2S or PCM connector terminal contact

•	A defective HO2S

Repair any of the above conditions as necessary.

Did you find and correct the condition?

Go to Step 14

Go to Diagnostic Aids

Turn OFF the ignition.
Disconnect the HO2S connector for the sensor that applies to this DTC.
Connect a test lamp between the HO2S heater ignition 1 voltage and ground circuit terminals.
Turn ON the ignition, leaving the engine OFF.

Does the test lamp illuminate?

Go to Step 5

Go to Step 6

Disconnect the test lamp.
Jumper the HO2S low reference circuit terminal to a known good ground.
Jumper the HO2S high signal circuit terminal to a known good ground.
Use the scan tool in order to monitor the HO2S voltage for the sensor that applies to this DTC.
Turn the ignition ON, leaving the engine OFF.

Is the voltage less than the specified value?

20 mV

Go to Step 8

Go to Step 7

Connect the test lamp between the HO2S heater ignition 1 voltage circuit terminal and a known good ground.
Turn the ignition ON, leaving the engine OFF.

Does the test lamp illuminate?

Go to Step 9

Go to Step 10

Turn OFF the ignition.
Remove the jumpers from the PCM connector containing the HO2S high and low reference circuits.
Use a digital multimeter (DMM) in order to measure the continuity of the HO2S high signal circuit and the HO2S low reference circuit between the PCM connector terminal and the HO2S connector terminal.

Is the resistance less than the specified value?

5 ohms

Go to Step 12

Go to Step 11

Replace the affected HO2S. Refer to Heated Oxygen Sensor Replacement - Bank 1 Sensor 1 , Heated Oxygen Sensor Replacement - Bank 2 Sensor 1 , Heated Oxygen Sensor Replacement - Bank 1 Sensor 2 , or Heated Oxygen Sensor Replacement - Bank 2 Sensor 2 .

Did you complete the replacement?

Go to Step 14

Repair the open HO2S heater ground circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the replacement?

Go to Step 14

Repair the lack of voltage on the HO2S heater ignition 1 voltage circuit. Refer to Wiring Repairs in Wiring Systems.
If the fuse is open, repair the short to ground on the circuit. An open fuse or a lack of voltage to the fuse may cause other DTCs or symptoms to be present.

Did you complete the repair?

Go to Step 14

Repair the circuit that has a high resistance. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 14

Check for proper PCM terminal contact.
Repair the PCM terminals as necessary. Refer to Connector Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 14

Go to Step 13

Replace the PCM. Refer to Powertrain Control Module Replacement .

Did you complete the replacement?

Go to Step 14

Use the scan tool in order to clear the DTCs.
Disconnect the scan tool.
Turn OFF the ignition for 30 seconds.
Start the engine.
Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.
Install the scan tool.

Does the DTC run and pass?

150 mV

Go to Step 15

Go to Step 2

With a scan tool, observe the stored information, Capture Info.

Does the scan tool display any DTCs that you have not diagnosed?

Go to Diagnostic Trouble Code (DTC) List

System OK