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For 1990-2009 cars only
Makes 🢒 Buick 🢒 1996 🢒 Regal 🢒 Engine 🢒 Engine Controls - 3.8L 🢒 DTC P1133 HO2S Insufficient Switching Sensor 1

Refer to

HO2S Sensors


Object Number: 23112 Size: FS
Engine Controls Components
Information Sensors
IAC Valve, Trans Range
MAF Sensor, EVAP System EGR Valve
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice
 .

Circuit Description

The powertrain control module (PCM) monitors the heated oxygen sensor (HO2S) activity for 100 seconds. During this test period the PCM counts the number of times that the HO2S signal voltage crosses the rich to lean and lean to rich thresholds. If the PCM determines that the HO2S did not switch enough times, DTC P1133 will be set. A lean to rich switch is determined when the HO2S voltage changes from less than 300 mV to greater than 600 mV. A rich to lean switch is determined when the HO2S voltage changes from more than 600 mV to less than 300 mV.

Conditions for Setting the DTC
    • The engine has been running at least 2 minutes.
    • Engine speed is between 1000 rpm and 3000 rpm.
    • Mass Air Flow is between 15 gm/s and 29 gm/s.
    • Engine Temperature above 65°C (149°F).
    • Above conditions present for a 100 second monitoring period.
    • The PCM monitors fewer than 45 rich to lean and 45 lean to rich switches for HO2S 1

Action Taken When the DTC Sets
    • The PCM will illuminate the malfunction indicator lamp (MIL) during the second consecutive trip in which the diagnostic test has been run and failed.
    • The PCM will store conditions which were present when the DTC set as Freeze Frame and Failure Records data.

Conditions for Clearing the MIL/DTC
    • The PCM will turn OFF the MIL during the third consecutive trip in which the diagnostic has been run and passed.
    • The History DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
    • The DTC can be cleared by using the scan tool.

Diagnostic Aids

A malfunction in the HO2S heater ignition feed or ground circuit may cause a DTC P1133 to set. Check HO2S heater circuitry for intermittent faults or poor connections. If connections and wiring are OK and DTC P1133 continues to set, replace the HO2S 1. Refer to Heated Oxygen Sensor Replacement .

Reviewing the Fail Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to be set occurs. This may assist in diagnosing the condition.

Test Description

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

  1. This step checks for conditions which may cause the heated oxygen sensor to appear faulty. Correct any of the described conditions if present.

    2.

  2. Before replacing the HO2S, check for silicon contamination.

DTC P1133 - HO2S Insufficient Switching Sensor 1

Step

Action

Value(s)

Yes

No

1

Was the Powertrain On-Board Diagnostic (OBD) System Check performed?

Go to Step 2

Go to the Powertrain On Board Diagnostic (OBD) System Check

2

Important:: If any DTCs are set (except P1133 or P1134), diagnose the applicble DTC(s) before proceeding with this diagnostic table.

  1. Select DTC info, Last Tst Fail and note any other DTCs set.
  2. Operate vehicle within parameters specified under Conditions for Setting the DTC criteria included in Diagnostic Support.
  3. Using a scan tool, monitor Specific DTC info for DTC P1133 until the DTC P1133 test runs.

Note test result; does the scan tool indicate DTC failed this ign?

Go to Step 3

Refer to Diagnostic Aids

3
  1. Perform the Exhaust System Leak Test. Refer to Exhaust System.
  2. If an exhaust leak is found, repair as necessary.

Was a problem found?

Go to Step 11

Go to Step 4

4

Visually/physically inspect the following items:

    • Ensure that the HO2S 1 is securely installed.
    • Check for corrosion on terminals.
    • Check terminal tension at HO2S 1 and at the PCM.
    • Check for damaged wiring.

Was a problem found in any of the above areas?

Go to Step 8

Go to Step 5

5
  1. Disconnect HO2S 1 and jumper HO2S low (PCM side) signal circuit to ground.
  2. Using a scan tool, monitor HO2S 1 voltage.

Does the scan tool indicate voltage near the specified value?

450mV

Go to Step 6

Go to Step 9

6
  1. Jumper HO2S 1 high and low (PCM side) signal circuits to ground.
  2. Using a scan tool, monitor HO2S 1 voltage.

Does scan tool indicate voltage less than the specified value?

300mV

Go to Step 7

Go to Step 10

7

Replace the affected Heated Oxygen Sensor(s). Go to Heated Oxygen Sensor Replacement .

Is action complete?

Go to Step 11

8

Repair the condition as necessary.

Is action complete?

Go to Step 11

9

Repair open HO2S 1 low signal circuit or grounded HO2S 1 high signal circuit. Refer to Heated Oxygen Sensor (O2S) Repair in Electrical Diagnosis.

Is action complete?

Go to Step 11

10

Repair open HO2S 1 high signal circuit or faulty PCM connections. Refer to Heated Oxygen Sensor (O2S) Repair in Electrical Diagnosis.

Is action complete?

Go to Step 11

11
  1. Clear DTCs.
  2. Operate vehicle within parameters specified under Conditions for Setting the DTC criteria included in Diagnostic Support.
  3. Using a scan tool, monitor Specific DTC info for DTC P1133 until the DTC P1133 test runs.

Note test result; does scan tool indicate DTC failed this ign?

Go to Step 2

System OK