DTC P0135 HO2S Heater Performance Bank 1 Sensor 1. Cadillac Catera 1999

For 1990-2009 cars only

Makes 🢒 Cadillac 🢒 1999 🢒 Catera 🢒 DTC 🢒 DTC P0135 HO2S Heater Performance Bank 1 Sensor 1

Engine Controls Components
Cell 20: Heated Oxygen Sensors
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice

Circuit Description

The HO2S heater circuit reduces the time required for the oxygen sensor to reach operating temperature and maintains the operating temperature during extended idle periods. When the ignition is turned to the on position, voltage is supplied to the sensor heater from the Engine Controls Power Relay through a fuse. The ECM controls the heater operation by first modulating the ground circuit when the sensors are cold, and then turning the heaters on continuously after a predetermined amount of time. This prevents the possibility of thermal shock to the sensor by controlling the sensor's rate of heating. Once the sensor reaches operating temperature, the ECM may again modulate the ground.

Conditions for Running the DTC

•	The battery voltage is between 11-15.5 volts.

•	The engine is running.

•	The sensor heater is on.

Conditions for Setting the DTC

•	The heater voltage is more than 3.6 volts, or less than 2.3 volts for more than 50 ms (0.05 seconds).

•	No system readiness is detected after 20 seconds of operation on a start occurring more than 4 minutes after the engine was last run.

Action Taken When the DTC Sets

The ECM illuminates the malfunction indicator lamp (MIL) and records the operating conditions in the Freeze Frame on the second consecutive drive trip that the diagnostic runs and fails.

Conditions for Clearing the MIL/DTC

•	The ECM turns OFF the MIL after three consecutive drive trips that the diagnostic runs and passes.

•	A History DTC clears after forty consecutive warm-up cycles in which no failures are reported by this diagnostic or any other emission related diagnostic.

•	The ECM battery voltage is interrupted.

•	The scan tool clears the MIL/DTC.

Diagnostic Aids

Notice: Using the J 35616-A Connector Test Adapter Kit will prevent damage to the harness connector terminals.

Use the Connector Test Adapter Kit J 35616 for any test that requires probing the ECM harness connector or a component harness connector. Using this kit will prevent damage to the harness connector terminals.

An open fuse in the HO2S heater circuit may be caused by the heater element in one of the sensors. The condition may not be present until the sensor operates for a period of time. If no fault is present in the heater circuit, monitor the amperage of each heater using the DMM to determine if one of the heater elements is the cause of the open fuse.

Check for the following conditions:

•	The sensor pigtail or the harness may be mis-positioned and contacting the exhaust system.

•	An intermittent or poor connection or corrosion in the connector. Refer to Intermittents and Poor Connections Diagnosis in Wiring Systems.

Test Description

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

Multiple DTCs will set if the supply voltage to the sensor heaters is open.

Any exhaust leak, even a small one, can affect the operation of the HO2S. The ECM compares the reading of sensor 1 with the reading of sensor 2 as part of the diagnosis. A leak between sensor 1 and sensor 2 may set a DTC.

The test lamp may illuminate or flash depending on the operating conditions. This indicates the ECM and the control circuit are functioning. The engine must be running for the ECM to operate the control circuit.

A short between the signal circuit and the reference ground circuit or the pump current input and output circuits may not appear on the voltage tests. The ECM must be disconnected and each circuit tested for continuity with the other HO2S circuits.

Heated Oxygen Sensor (HO2S) Heater Circuit Sensor 1

Step

Action

Values

Yes

Did you perform the Powertrain On-Board Diagnostic (OBD) System check?

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

Using the scan tool, observe the DTC information.

Are all of the HO2S heater DTCs set?

Go to Step 3

Go to Step 4

Turn OFF the ignition.
Inspect fuse 43 for the oxygen sensor heaters located in the ECM housing.

Is fuse 43 open?

Go to Step 19

Go to Step 20

Inspect the exhaust system for any leaks upstream from the affected oxygen sensor.
Inspect for any exhaust leaks between sensor 1 and sensor 2.
Repair the exhaust leak as necessary.

Did you find and repair an exhaust leak?

Go to Step 27

Go to Step 5

Important: The ignition must be OFF when disconnecting or connecting the HO2S electrical connector.

Turn OFF the ignition.
Disconnect the HO2S electrical connector.
Inspect both halves of the connector for any signs of corrosion or contamination.

Did you find a problem?

Go to Step 21

Go to Step 6

Turn ON the ignition leaving the engine OFF.
Using a test lamp connected to ground, probe the switched B+ circuit at the ECM side of the oxygen sensor connector.

Does the test lamp illuminate?

Go to Step 7

Go to Step 23

Turn OFF the ignition.
Connect a test lamp between the switched B+ circuit and the heater control circuit at the ECM side of the oxygen sensor connector.
Turn the ignition ON leaving the engine OFF.

Does the test lamp illuminate?

Go to Step 8

Go to Step 9

Turn OFF the ignition.
Disconnect the ECM electrical connector (C1).
With the test lamp still connected between the switched B+ and the control circuit, turn ON the ignition.

Does the test lamp illuminate?

Go to Step 22

Go to Step 26

Start the engine and allow the engine to idle.
Observe the test lamp.

Does the test lamp illuminate or flash?

Go to Step 10

Go to Step 18

Turn OFF the ignition.
Remove the test lamp.
Turn ON the ignition leaving the engine OFF.
Measure the voltage of the HO2S signal circuit at the ECM side of the connector to battery ground.

Is the voltage within the specified value?

2-4 V

Go to Step 11

Go to Step 15

Measure the voltage of the HO2S reference ground circuit at the ECM side of the connector to battery ground.

s the voltage within the specified value?

2-4 V

Go to Step 12

Go to Step 15

Measure the voltage of the HO2S pump current input circuit at the ECM side of the connector to battery ground.

s the voltage within the specified value?

0.2-0.4 V

Go to Step 13

Go to Step 15

Measure the voltage of the HO2S pump current output circuit at the ECM side of the connector to battery ground.

s the voltage within the specified value?

0.2-0.4 V

Go to Step 14

Go to Step 15

Turn OFF the ignition.
Disconnect the ECM connector (C1).
Test each of the circuits on the affected HO2S for a short to each other.
Repair the circuit as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct a problem?

Go to Step 27

Go to Step 24

Was the voltage above the specified value?

Go to Step 17

Go to Step 16

Test the affected circuit for the following conditions:

•

Open

•	Short to ground

•	High resistance

Repair the circuit as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct a problem?

Go to Step 27

Go to Step 25

Test the affected circuit for a short to voltage.
Repair the circuit as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct a problem?

Go to Step 27

Go to Step 25

Turn OFF the ignition.
Disconnect the ECM connector (C1).
Test the heater control circuit for an open, high resistance or a short to voltage.
Repair the circuit as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct a problem?

Go to Step 27

Go to Step 25

Test the switched B+ circuit for a short to ground.
Repair the circuit as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct a problem?

Go to Step 27

Go to Diagnostic Aids

Locate and repair the open in the switched B+ circuit from the Engine Controls Power Relay to the splice for the oxygen sensors. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

Go to Step 27

Repair or replace the terminal as necessary. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

Go to Step 27

Repair the short to ground in the heater control circuit. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

Go to Step 27

Repair the open in the B+ circuit from the splice to the oxygen sensor. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

Go to Step 27

Replace the HO2S. Refer to Heated Oxygen Sensor Replacement .

Is the replacement complete?

Go to Step 27

Test for a poor connection or poor terminal tension at the ECM harness connector. Refer to Intermittents and Poor Connections Diagnosis in Wiring Systems.
Repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct a problem?

Go to Step 27

Go to Step 26

Important:

•	Perform the idle learn procedure when replacing the ECM.

•	This vehicle is equipped with a Theft Deterrent System that interfaces with the ECM. Program the new ECM with the frequency code of the theft deterrent module that is currently in the vehicle.

Replace the ECM. Refer to Engine Control Module Replacement/Programming .

Is the action complete?

Go to Step 27

Using the scan tool, clear the DTCs.
Start the engine.
Allow the engine to idle until the engine reaches the normal operating temperature.
Select DTC and the Specific DTC function.
Enter the DTC number that was set.
Operate the vehicle within the Conditions for Running this DTC until the scan tool indicates that the diagnostic Ran.

Does the scan tool indicate that the diagnostic Passed?

Go to Step 28

Go to Step 2

Does the scan tool display any additional undiagnosed DTCs?

Go to the applicable DTC table

System OK