Engine-Codes - Gmc - P0133 GMC

P0133 GMC Code - HO2S Slow Response Bank 1 Sensor 1

- Code Popularity: 8,949 Views
- Repair Importance Level: 2/3
- Repair Difficulty Level: 2/3
Table of contents

|What are the Possible Causes of the P0133 GMC Code?

  • Faulty Heated Oxygen Sensor (HO2S) Bank 1 Sensor 1
  • Heated Oxygen Sensor Bank 1 Sensor 1 harness is open or shorted
  • Heated Oxygen Sensor Bank 1 Sensor 1 circuit poor electrical connection
  • Low or high fuel system pressure
  • Fuel contamination
  • Faulty fuel injectors
  • Exhaust gas leaks
  • Engine vacuum leaks

|How to Fix the P0133 GMC Code?

Start by checking the "Possible Causes" listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector's pins.

|P0133 GMC code tech notes

Replacing the Front Heated Oxygen Sensors (HO2S) usually takes care of the problem

|What is the cost to diagnose the P0133 GMC code?

Labor: 1.0

The cost to diagnose the P0133 GMC code is 1.0 hour of labor. The auto repair's diagnosis time and labor rates vary by location, vehicle's make and model, and even your engine type. Most auto repair shops charge between $75 and $150 per hour.

|What are P0133 GMC code possible symptoms?

  • Engine Light ON (or Service Engine Soon Warning Light)
  • High Fuel Consumption
  • Excessive Smoke from Exhaust

|What Does the P0133 GMC Code Mean?

The Heated Oxygen Sensors (HO2S) are used for fuel control and catalyst monitoring. Each HO2S compares the oxygen content of the surrounding air with the oxygen content of the exhaust stream. When the engine is started, the Engine Control Module (ECM) operates in an Open Loop mode, ignoring the HO2S signal voltage while calculating the air-to-fuel ratio. While the engine runs, the HO2S heats up and begins to generate a voltage within a range of 0 - 1, 000 mV. Once sufficient HO2S voltage fluctuation is observed by the ECM, Closed Loop is entered. The ECM uses the HO2S voltage to determine the air-to-fuel ratio. An HO2S voltage that increases toward 1, 000 mV indicates a rich fuel mixture. An HO2S voltage that decreases toward 0 mV indicates a lean fuel mixture.
The heating elements inside each HO2S heat the sensor to bring the sensor up to operating conditions faster. This allows the system to enter Closed Loop earlier and the ECM to calculate the air-to-fuel ratio sooner.
The Diagnostic Trouble Code (DTC) will be set when the ECM detects that the HO2S 1 rich-to-lean or lean-to-rich average response time is greater than a calibrated value for greater than 60s.
HO2S Slow Response Bank 1 Sensor 1

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