AutoCodes – GMC – P1133 2015 GMC Sierra

P1133 2015 GMC Sierra Code - HO2S Insufficient Switching Bank 1 Sensor 1

Quick Answer

The Heated Oxygen Sensors (HO2S) are used for fuel control and catalyst monitoring. Common causes include 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. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means: P1133 2015 GMC Sierra indicates HO2S Insufficient Switching Bank 1 Sensor 1.
Common causes: Common causes include 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.
Severity: High - diagnose this code as soon as possible.
Can I drive?: Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

Save to My Repairs Step-by-Step Diagnostic Guide My Repairs

AI answers can be wrong. Verify repairs with testing. Open full chat

Code Popularity 191

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Intermediate (2 / 3)

What is this?

Table of contents Created and updated by William Orellana on May 28, 2022

Description
Step-by-Step Diagnostic Guide
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
Add Comment

💬 Need more help? Ask Coddy for instant answers — it's free!

Code P1133 2015 GMC Sierra Description

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 heated oxygen sensor rich-to-lean counts or the lean-to-rich counts are less than a calibrated value greater than 100s.

OBDII Code P1133 2015 GMC Sierra - HO2S Insufficient Switching Bank 1 Sensor 1 - AutoCodes.com — P1133 2015 GMC Sierra Code - HO2S Insufficient Switching Bank 1 Sensor 1

What does this mean?

What are the Possible Causes of the DTC P1133 2015 GMC Sierra?

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 DTC P1133 2015 GMC Sierra?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What does this mean?

Code Tech Notes

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

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P1133 2015 GMC Sierra code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

Need more information about the P1133 2015 GMC Sierra code?

Need more information on how to fix the P1133 2015 GMC Sierra code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P1133 2015 GMC Sierra code diagnosed by a professional: Find a repair shop in your area

About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about P1133 2015 GMC Sierra Code

1. What does the OBDII code P1133 mean on a 2015 GMC Sierra?

P1133 indicates that the Powertrain Control Module (PCM) has detected insufficient switching activity in the upstream oxygen sensor (Bank 1, Sensor 1), which monitors air-fuel mixture.

2. What are common symptoms of code P1133 on a 2015 GMC Sierra?

Symptoms may include the Check Engine Light illuminating, poor fuel economy, rough idling, hesitation during acceleration, or reduced engine performance.

3. What causes the P1133 code to trigger on a 2015 GMC Sierra?

Common causes include a faulty oxygen sensor, exhaust leaks, wiring issues, contaminated sensor due to oil or coolant, or a malfunctioning PCM.

4. Which sensor is affected by the P1133 code on a 2015 GMC Sierra?

The code refers to the upstream oxygen sensor (Bank 1, Sensor 1) located before the catalytic converter on the side of the engine with cylinder 1.

5. Can a dirty or clogged air filter cause the P1133 code?

While rare, a severely restricted air filter can lead to incorrect air-fuel ratios, potentially affecting oxygen sensor readings and triggering the code.

6. How can I diagnose the P1133 code on my 2015 GMC Sierra?

Diagnosis involves inspecting the oxygen sensor and wiring, checking for exhaust leaks, testing the air-fuel ratio, and using a scan tool to monitor oxygen sensor voltage.

7. Can I drive my 2015 GMC Sierra with the P1133 code?

Driving with this code is possible, but itâ€™s not recommended as it can lead to poor performance, worsen emissions, and potentially damage the catalytic converter over time.

8. How do I fix the P1133 code on a 2015 GMC Sierra?

Repairs may include replacing the faulty oxygen sensor, fixing exhaust leaks, repairing damaged wiring, or addressing air-fuel mixture issues.

9. How much does it cost to repair the P1133 code on a 2015 GMC Sierra?

Replacing an oxygen sensor typically costs between $150 and $400, including parts and labor, though costs vary by location and shop.

10. Can a bad PCM cause the P1133 code on a 2015 GMC Sierra?

While rare, a faulty PCM can cause this code, but itâ€™s usually the last thing to check after ruling out more common causes like the oxygen sensor or wiring issues.