AutoCodes – Generic – P1133

P1133 Code - HO2S Insufficient Switching 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 indicates HO2S Insufficient Switching 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.

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Code Popularity 72,488

How popular is this code, among other codes? Medium

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
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Code P1133 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 - HO2S Insufficient Switching Sensor 1 - AutoCodes.com — P1133 Code - HO2S Insufficient Switching Sensor 1

What does this mean?

What are the Possible Causes of the DTC P1133?

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?

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.

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What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P1133 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.

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Information for Specific Makes

P1133 Acura — HO2S Insufficient Switching Sensor 1
P1133 Audi — HO2S Heater Circuit- Bank 1 & 2 Sensor 1 Electrical Malfunction
P1133 BMW — HO2S Insufficient Switching Sensor 1
P1133 Buick — HO2S Insufficient Switching Bank 1 Sensor 1
P1133 Cadillac — HO2S Insufficient Switching Bank 1 Sensor 1
P1133 Chevrolet — HO2S Insufficient Switching Bank 1 Sensor 1
P1133 Dodge — ECT Sensor Circuit Interm Low Voltage
P1133 Ford — Bank 1 Fuel Control Shifted Lean
P1133 GMC — HO2S Insufficient Switching Bank 1 Sensor 1
P1133 Honda — HO2S Insufficient Switching Sensor 1
P1133 Isuzu — H02S Insufficient Switching Bank 1 Sensor 1
P1133 Lexus — Air/Fuel Ratio Sensor Circuit Response Malfunction Bank 1 Sensor 1
P1133 Lincoln — Bank 1 Fuel Control Shifted Lean
P1133 Mazda — Bank 1 Fuel Control Shifted Lean
P1133 Mercury — Bank 1 Fuel Control Shifted Lean
P1133 Pontiac — HO2S Insufficient Switching Bank 1 Sensor 1
P1133 Saturn — HO2S Insufficient Switching Bank 1 Sensor 1
P1133 Scion — Air/Fuel Ratio Sensor Circuit Response Malfunction Bank 1 Sensor 1
P1133 Subaru — Front Oxygen Sensor Heater Circuit High Input
P1133 Suzuki — HO2S11 Too Few Transitions
P1133 Toyota — Air/Fuel Ratio Sensor Circuit Response Malfunction Bank 1 Sensor 1
P1133 Volkswagen — HO2S Heater Circuit- Bank 1 & 2 Sensor 1 Electrical Malfunction

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 Code

1. What are the common symptoms of OBDII code P1133?

- Common symptoms of P1133 include poor engine performance, rough idle, reduced fuel efficiency, and the illumination of the Check Engine light.

2. What does the OBDII code P1133 indicate?

- P1133 indicates an issue with the Heated Oxygen Sensor (HO2S) for Bank 1 Sensor 1, specifically insufficient switching activity.

3. What are the potential causes of OBDII code P1133?

- The potential causes of P1133 can include a faulty HO2S sensor, wiring issues, vacuum leaks, exhaust system leaks, or a problem with the engine control module (ECM).

4. How can I diagnose the cause of OBDII code P1133?

- Diagnosing P1133 typically involves checking the HO2S sensor for proper operation, inspecting the wiring for any damage, and testing for vacuum or exhaust leaks.

5. Can a dirty or contaminated HO2S sensor cause code P1133?

- Yes, a dirty or contaminated HO2S sensor can lead to insufficient switching activity and trigger code P1133. Cleaning or replacing the sensor may resolve the issue.

6. Are there any repair tips for resolving OBDII code P1133?

- Repair tips for P1133 include checking and cleaning the sensor connections, inspecting for leaks, confirming proper sensor operation, and resetting the ECM after repairs.

7. How serious is OBDII code P1133?

- While P1133 may not cause immediate drivability issues, it can lead to decreased engine performance and efficiency if left unresolved. It is recommended to address the code promptly.

8. Can I drive my vehicle with OBDII code P1133?

- It is generally safe to drive with P1133, but it is advisable to address the issue promptly to prevent potential engine performance problems and further damage.

9. Will resetting the Check Engine light clear OBDII code P1133?

- Resetting the Check Engine light may temporarily clear the code, but if the underlying issue causing P1133 is not addressed, the code is likely to reappear after driving cycles.

10. How much does it typically cost to repair OBDII code P1133?

- The cost of repairing P1133 can vary depending on the underlying cause. It may involve sensor replacement, wiring repairs, or other fixes, with costs ranging from $100 to $500 or more.