DTC P0135, P0141, P0155, or P0161. GMC Truck GMC C Sierra

For 1990-2009 cars only

Makes 🢒 GMC_Truck 🢒 2002 🢒 GMC C Sierra - 2WD 🢒 DTC 🢒 DTC P0135, P0141, P0155, or P0161

DTC P0135, P0141, P0155, or P0161 California W/ RPO LU3

Circuit Description

The heated oxygen sensor (HO2S) is a sensor designed to create a voltage relative to the oxygen content in the engine exhaust stream. The control module supplies the HO2S with signal high and low circuits. Ignition voltage and ground are supplied to the HO2S heater by independent circuits. The oxygen content of the exhaust indicates when the engine is operating lean or rich. When the HO2S detects that the engine is operating rich, the signal voltage is high, and decreases the signal voltage as the engine runs leaner. This oscillation above and below the bias voltage, sometimes referred to as activity or switching, can be monitored with the HO2S signal voltage.

The HO2S contains a heater that is necessary in order to quickly warm the sensor to operating temperature. The heater also maintains the operating temperature during extended idle conditions. The HO2S needs to be at a high temperature in order to produce a voltage. When the HO2S reaches operating temperature, the control module monitors the HO2S bias, or reference, voltage. The control module the HO2S signal voltage for Closed Loop fuel control. During normal Closed Loop fuel control operation, the control module will add fuel, or enrich the mixture, when the HO2S detects a lean exhaust content. The control module will subtract fuel, or lean-out the mixture, when the HO2S detects a rich exhaust condition.

This DTC determines if the HO2S heater circuit is functioning properly by monitoring the time required for the HO2S to reach operating temperature. This DTC sets when the PCM fails to detect HO2S voltage transitions above and below the bias range within a specified amount of time.

Conditions for Running the DTC

•	DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0121, P0122, P0123, P0200, P0300, P0401, P0404, P0405, P0440, P0442, P0446, P0452, P0453, P1404, or P1441 are not set.

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

•	The intake air temperature (IAT) sensor and the engine coolant temperature (ECT) sensor 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.

•	Scan tool output controls are not active.

Conditions for Setting the DTC

P0135 or P0155

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

P0141 or P0161

The HO2S voltage remains within 75 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.

•

Use the Freeze Frame/Failure Records in order to help locate an intermittent condition. If you cannot duplicate the DTC, the information in the Freeze Frame/Failure Records can help to determine how many miles have occurred since the DTC set. The Fail Counter and the Pass Counter can also help determine how many ignition cycles the diagnostic reported a pass or a fail. In order to isolate when the DTC failed, operate the vehicle within the same Freeze Frame conditions such as RPM, load, vehicle speed, temperature, etc. that you observed. For an intermittent condition, refer to Symptoms - Engine Controls . These conditions include:

The RPM

-	The vehicle load

-	The vehicle speed

-	The temperature

•	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 inspect the connections for breaks or for 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.

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

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, with 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, with the engine OFF.

Does the test lamp illuminate?

Go to Step 5

Go to Step 6

Disconnect the test lamp.
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, with 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, with 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 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.
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.

Does the DTC run and pass?

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

DTC P0135, P0141, P0155, or P0161 Federal W/ RPO L35

Circuit Description

Conditions for Running the DTC

•	DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0121, P0122, P0123, P0200, P0300, P0401, P0404, P0405, P0440, P0442, P0446, P0452, P0453, P1404, or P1441 are not set.

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

•	The intake air temperature (IAT) sensor and the engine coolant temperature (ECT) sensor 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.

•	Scan tool output controls are not active.

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 airflow.

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

•

The RPM

-	The vehicle load

-	The vehicle speed

-	The temperature

•	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 inspect the connections for breaks or for 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 you perform this test. If the sensor is at the operating temperature, the HO2S voltage will stay high or low. If the HO2S voltage stays between 300-600 mV, the HO2S heater is inoperative.

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

This step tests whether an Ignition 1 positive voltage supply is available at the sensor.

This step tests whether a ground is available at the sensor.

This step tests whether the HO2S heater element is internally open.

Inspect the ignition 1 positive voltage circuits at the underhood electrical center for poor connections.

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

Step	Action	Values	Yes	No
Schematic Reference: Engine Controls Schematics
1	Did you perform the Diagnostic System Check-Engine Controls?	--	Go to Step 2	Go to Diagnostic System Check - Engine Controls
2	Important: Allow the engine to cool for one-half hour before proceeding with this table. Important: If DTC P0300 is set, diagnose that DTC first. Refer to Diagnostic Trouble Code (DTC) List . Install a scan tool. Turn ON the ignition, with the engine OFF. Immediately observe the affected HO2S voltage for 2 minutes. Does the HO2S voltage go from bias voltage to more than or less than the specified range?	300-600 mV	Go to Diagnostic Aids	Go to Step 3
3	Inspect the HO2S fuse for an open. Is the HO2S fuse open?	--	Go to Step 11	Go to Step 4
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 the J 35616-200 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
5	Connect the J 35616-200 between the HO2S ignition 1 voltage and the HO2S heater ground. Does the test lamp illuminate?	--	Go to Step 6	Go to Step 8
6	Measure the resistance between the HO2S ignition 1 voltage and the HO2S heater ground at the HO2S pigtail using the DMM. Is the HO2S resistance within the specified range?	2-50 ohms	Go to Step 9	Go to Step 10
7	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 action?	--	Go to Step 12	--
8	Repair the open in the HO2S heater ground circuit. Refer to Heated Oxygen Sensor Wiring Repairs in Wiring Systems. Did you complete the action?	--	Go to Step 12	--
9	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 repair the condition?	--	Go to Step 12	Go to Step 10
10	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 action?	--	Go to Step 12	--
11	Locate and repair the short to ground in the HO2S ignition 1 voltage circuit. Refer to Heated Oxygen Sensor Wiring Repairs in Wiring Systems. Replace the open fuse. Did you complete the action?	--	Go to Step 12	--
12	Use the scan tool in order to clear the DTCs. 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. Does the DTC run and pass?	--	Go to Step 13	Go to Step 2
13	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