DTC P1153 HO2S Insufficient Switching Bank 2 Sensor 1. Cadillac Concours 1996

For 1990-2009 cars
Engine Controls Components
Heated Oxygen Sensors
OBD II Symbol Description Notice
ESD Notice

### Circuit Description

The PCM provides a 0.45 volt reference signal to the oxygen sensor on CKT 412. When the oxygen sensor is cold, below 200°C (392°F), the oxygen sensor signal voltage will be around 0.45 volt and the PCM will keep the system in Open Loop operation. When the oxygen sensor is warm, above 200°C (392°F), the oxygen sensor will swing from rich to lean rapidly, if the PCM is in good control of the air fuel mixture. DTC P1153 is designed so that if the oxygen sensor is slow to respond to changes in exhaust oxygen content, then DTC P1153 will set.

### Conditions for Setting the DTC

#### Test Conditions

• | DTCs P117, P118, P0121, P0122, P0123, and P0155 not set.

• | This test has not been completed yet this ignition cycle.

• | Low coolant level not present.

#### Failure Conditions

• | Number of rich to lean transitions less than 20 in 120 seconds.

| OR

• | Number of lean to rich transitions less than 20 in 120 seconds.

### Action Taken When the DTC Sets

• | The PCM will illuminate the malfunction indicator lamp (MIL) when the diagnostic runs and fails.

• | The PCM will record operating conditions at the time the diagnostic fails. This information will be stored in the Freeze Frame and Failure Records.

### Conditions for Clearing the MIL/DTC

• | The PCM will turn the MIL OFF after three consecutive drive trips that the diagnostic runs and does not fail.

• | A Last Test Failed (current) DTC will clear when the diagnostic runs and does not fail.

• | A History DTC will clear after forty consecutive warm-up cycles with no failures of any emission related diagnostic test.

• | Use a scan tool to clear DTCs.

• | Interrupting PCM battery voltage may or may not clear DTCs. This practice is not recommended. Refer to Clearing Diagnostic Trouble Codes in PCM Description and Operation.

### Diagnostic Aids

Notice: Do not solder heated oxygen sensor wires. Soldering the wires will result in the loss of the air reference to the sensor. Refer to Engine Electrical for proper wire and connection repair techniques.

If fault is not present perform Powertrain Ground Check and also review Failure Rec. to determine conditions under which and how long ago the DTC set.

### Test Description

Number(s) below refer to the step number(s) on the Diagnostic Table.

1. Checking if other possible causes of this DTC have already been diagnosed.

2. Diagnose other DTCs first because they may be the cause of this DTC setting.

3. With the engine running warm, coolant at least 85°C (185°F) and at fast idle, the oxygen sensor voltage should rapidly swing above 0.60 volt and below 0.30 volt.

4. Checking if the oxygen sensor voltage is swinging between rich and lean very slowly, or not at all.

5. Checking for causes of oxygen sensor failure. If sensor is replaced without finding cause of contamination, contamination of new sensor may result.

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | Go to Step 2 | Go to A Powertrain On Board Diagnostic (OBD) System Check
2 | Were you sent here from another DTC? | -- | Go to Step 4 | Go to Step 3
3 | Are any other PCM DTCs set? | -- | Diagnose other PCM DTCs first | Go to Step 4

4

1. Start the engine.
2. Using a scan tool observe the ECT display and operate engine until temperature reaches the value specified.
3. View both the Engine Speed and the Bnk 2 Sns 1 displays.
4. Operate engine at a steady speed within the range specified for two minutes.

After the two minutes does the Front oxygen sensor voltage rapidly swing above and below the range specified?

85°C (185°F)

1200 - 2000 RPM

0.30 - 0.60 volts

Go to Step 5

Go to Step 6

5 | With engine running at 1200-2000 RPM, check the scan tool display Loop Status. Does the display indicate Closed? | -- | Fault not present refer to Diagnostic Aids | Go to Step 9
6 | Does the Front oxygen sensor voltage remain between the range specified longer than it swings outside this range? | 0.30 - 0.60 volts | Go to Step 9 | Go to Step 7

7

1. Check terminal contact at PCM connector C2 terminals 69 and 70.
2. Repair terminal contact if needed.

Was terminal contact repaired?

--

Go to Powertrain Control Module Diagnosis for Verify Repair

Go to Step 8

8

1. Check terminal contact at the front oxygen sensor connector.
2. Repair terminal contact if needed.

Is terminal contact OK?

--

Go to Powertrain Control Module Diagnosis for Verify Repair

Go to Step 9

9

1. Replace the Front oxygen sensor. Refer to Heated Oxygen Sensor (HO2S) Replacement (Front) .
2. Check for the following possible causes of oxygen sensor contamination:

• | Leaded fuel.

• | Incorrect gasket sealer.

• | Over rich operation.

Were any of these possible cause found?

--

Take necessary corrective action

Refer to Fuel System Check