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Discussion Starter · #1 ·
Both codes are showing, I checked P300 and one cause could be O2 sensor which is the second code! replacing the sensor on Bank 1 is ofcourse the easy way, but what should I check before I replace? I am only hoping that P300 is as a reslut of P1133! otherwise, I'm for up for more trouble!any one can help guys would be much appricated.:neutral:

532 Posts
a little help on what your driving ?

532 Posts

DTC P1133

Heated oxygen sensors (HO2S) are used for fuel control and post catalyst monitoring. Each HO2S compares the oxygen content of the surrounding air with the oxygen content in the exhaust stream. The HO2S must reach operating temperature to provide an accurate voltage signal. Heating elements inside the HO2S minimize the time required for the sensors to reach operating temperature. The powertrain control module (PCM) supplies the HO2S with a reference, or bias, voltage of about 450 mV . When the engine is first started the PCM operates in open loop, ignoring the HO2S voltage signal. Once the HO2S reaches operating temperature and closed loop is achieved, the HO2S generates a voltage within a range of 0-1,000 mV that fluctuates above and below bias voltage. High HO2S voltage indicates a rich exhaust stream; low HO2S voltage indicates a lean exhaust stream. This diagnostic will only run once per ignition cycle. The PCM monitors the number of rich-to-lean and lean-to-rich transitions. If the PCM detects that the number of transitions were less than a specified value, DTC P1133 sets for HO2S bank 1 sensor 1, or DTC P1153 sets for HO2S bank 2 sensor 1.


* DTCs P0068, P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120, P0131, P0132, P0134, P0135, P0151, P0152, P0154, P0155, P0169, P0178, P0179, P0200, P0220, P0300, P0442, P0446, P0452, P0453, P0455, P0496, P1125, P1258, P1516, P2101, P2108, P2135, U0107 are not set.
* The ECT Sensor parameter is more than 60°C (140°F) .
* The EVAP Purge Solenoid Command parameter is more than 1 percent .
* The Fuel Alcohol content parameter is less than 90 percent .
* The MAF Sensor parameter is between 20-55 g/s .
* The Engine Speed parameter is between 1,200-3,000 RPM .
* The TP Indicated Angle parameter is 5 percent more than the value observed at idle.
* The Loop Status parameter is closed.
* The Ignition 1 Signal parameter is between 10-18 volts .
* The Fuel Tank Level Remaining parameter is more than 10 percent .
* The Engine Run Time parameter is more than 160 seconds .
* The above conditions are met for 100 seconds .

The PCM detects that the affected HO2S lean-to-rich or rich-to-lean transitions are less than a calibrated value.


* 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.


* 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.

Heated Oxygen Sensor (HO2S) Replacement Bank 1 Sensor 1



1. Raise and suitably support the vehicle. Refer to Vehicle Lifting.
2. If necessary, unbolt the front propeller shaft from the front differential.
3. Disconnect the connector position assurance (CPA) retainer. NOTE: Refer to Heated Oxygen and Oxygen Sensor Notice in Service Precautions.

4. Remove the heated oxygen sensor (HO2S) electrical connector from the fuel line clip.
5. If equipped with a 4.8L or 5.3L engine, disconnect the HO2S electrical connector (1).

6. If equipped with a 6.0L engine, disconnect the HO2S electrical connector (1).

7. Remove the HO2S. NOTE: Refer to Excessive Force and Oxygen Sensor Notice in Service Precautions.


IMPORTANT: A special anti-seize compound is used on the HO2S threads. The compound consists of liquid graphite and glass beads. The graphite tends to burn away, but the glass beads remain, making the sensor easier to remove. New, or service replacement sensors already have the compound applied to the threads. If the sensor is removed from an exhaust component and if for any reason the sensor is to be reinstalled, the threads must have anti-seize compound applied before the reinstallation.

1. If reinstalling the old sensor, coat the threads with anti-seize compound GM P/N 12377953, or equivalent. NOTE: Refer to Component Fastener Tightening Notice in Service Precautions.
2. Install the HO2S. Tighten the sensor to 42 N.m (31 lb ft) .

3. If equipped with a 6.0L engine, connect the HO2S electrical connector (1).

4. If equipped with a 4.8L or 5.3L engine, connect the HO2S electrical connector (1).
5. Install the HO2S electrical connector to the fuel line clip.
6. Disconnect the CPA retainer.
7. If necessary, bolt the front propeller shaft to the front differential.
8. Lower the vehicle.
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