P0139 Code - O2 Sensor Circuit Slow Response Bank 1 Sensor 2
Quick Answer
The O2 Sensor Circuit Slow Response Bank 1 Sensor 2 diagnostic trouble code (DTC) P0139 indicates that the oxygen sensor located in the exhaust system after the catalytic converter on bank 1 (the side of the engine where cylinder 1 is located) is not responding as quickly as expected by the Engine Control Module (ECM). Common causes include Faulty oxygen sensor, Wiring issues (e.g., damaged wires, poor connections), Exhaust leaks near the sensor. Severity is Moderate - service should be scheduled soon. The vehicle may still be drivable for short trips if it runs normally, but avoid hard driving and repair it soon.
- What it means
- P0139 indicates O2 Sensor Circuit Slow Response Bank 1 Sensor 2.
- Common causes
- Common causes include Faulty oxygen sensor, Wiring issues (e.g., damaged wires, poor connections), Exhaust leaks near the sensor.
- Severity
- Moderate - service should be scheduled soon.
- Can I drive?
- The vehicle may still be drivable for short trips if it runs normally, but avoid hard driving and repair it soon.
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Code P0139 Description
The O2 Sensor Circuit Slow Response Bank 1 Sensor 2 diagnostic trouble code (DTC) P0139 indicates that the oxygen sensor located in the exhaust system after the catalytic converter on bank 1 (the side of the engine where cylinder 1 is located) is not responding as quickly as expected by the Engine Control Module (ECM). This sensor, also known as the downstream oxygen sensor, is responsible for monitoring the efficiency of the catalytic converter and providing feedback to the ECM to adjust the air-fuel mixture for optimal combustion.
Common Causes of P0139
- Faulty oxygen sensor
- Wiring issues (e.g., damaged wires, poor connections)
- Exhaust leaks near the sensor
- Faulty catalytic converter
- ECM software issues
Symptoms of P0139
- Decreased fuel efficiency
- Rough idling or hesitation
- Check Engine Light illuminated
- Increased emissions
- Decreased engine performance
How to Fix P0139
- Use an OBD-II scanner to confirm the P0139 code and ensure it is not a false alarm.
- Inspect the wiring harness and connections for any damage or corrosion. Repair or replace as needed.
- Check for exhaust leaks near the sensor and repair them if present.
- Test the oxygen sensor's response time using a multimeter or oscilloscope. Replace the sensor if it is not responding quickly enough.
- Clear the DTC and test drive the vehicle to ensure the issue has been resolved.
Cost to Fix P0139
The cost to repair a P0139 code can vary depending on the specific cause of the issue. In general, replacing an oxygen sensor can cost between $100 and $250 for the part, with additional labor costs ranging from $50 to $150. If wiring repairs or catalytic converter replacement are needed, the total repair cost could increase significantly. It is advisable to consult with a qualified mechanic or auto repair shop to get an accurate estimate based on the specific circumstances of your vehicle.
Tech Notes for P0139
When is the Code Detected?
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Code P0139 Information for Specific Makes
- P0139 Acura — Secondary Heated Oxygen Sensor 2 Slow Response
- P0139 Audi — HO2S12 Sensor Circuit Slow Response
- P0139 BMW — O2 Sensor Circuit Slow Response Bank 1 Sensor 2
- P0139 Buick — HO2S Slow Response Bank 1 Sensor 2
- P0139 Cadillac — HO2S Slow Response Bank 1 Sensor 2
- P0139 Chevrolet — HO2S Slow Response Bank 1 Sensor 2
- P0139 Chrysler — O2 sensor 1/2 Slow response
- P0139 Dodge — O2 sensor 1/2 Slow response
- P0139 Ford — O2 Sensor Circuit Slow Response Bank 1 Sensor 2
- P0139 GMC — HO2S Slow Response Bank 1 Sensor 2
- P0139 Honda — Secondary Heated Oxygen Sensor 2 Slow Response
- P0139 Hummer — HO2S Slow Response Bank 1 Sensor 2
- P0139 Hyundai — HO2S Circuit Slow Response Bank 1 Sensor 2
- P0139 Infiniti — HO2S12 Slow Response
- P0139 Jeep — O2 sensor 1/2 Slow response
- P0139 KIA — HO2S12 Circuit Slow Response
- P0139 Lexus — Oxygen Sensor Circuit Slow Response Bank 1 Sensor 2
- P0139 Mazda — HO2S RR Circuit Problem
- P0139 Mercedes-Benz — O2 Sensor Circuit Slow Response Bank 1 Sensor 2
- P0139 MINI — O2 Sensor Circuit Slow Response Bank 1 Sensor 2
- P0139 Mitsubishi — Cylinder 1-4 Heated Oxygen Rear Sensor Circuit Slow Response
- P0139 Nissan — HO2S12 Slow Response
- P0139 Pontiac — HO2S Slow Response Bank 1 Sensor 2
- P0139 Saturn — HO2S Slow Response Bank 1 Sensor 2
- P0139 Scion — Oxygen Sensor Circuit Slow Response Bank 1 Sensor 2
- P0139 Subaru — HO2S12 Circuit Slow Response
- P0139 Toyota — Oxygen Sensor Circuit Slow Response Bank 1 Sensor 2
- P0139 Volkswagen — HO2S12 Sensor Circuit Slow Response
Frequently Asked Questions about P0139 Code
What does the OBDII code P0139 mean?
P0139 indicates that the oxygen sensor in Bank 1, Sensor 2 is responding slower than expected to changes in the air-fuel mixture.
What are common symptoms of code P0139?
Symptoms may include decreased fuel efficiency, rough idling, engine hesitation, or an illuminated check engine light.
What causes the P0139 code to appear?
Common causes include a faulty oxygen sensor, damaged wiring or connectors, exhaust leaks near the sensor, or engine issues affecting the air-fuel ratio.
Can I drive my car with a P0139 code?
While your car may still be drivable, ignoring the code can lead to decreased performance, higher emissions, and potential damage to other components like the catalytic converter.
How do I diagnose the P0139 code?
Diagnosis typically involves inspecting the oxygen sensor, checking for exhaust leaks, testing wiring and connectors for damage, and using a scan tool to monitor sensor performance.
How can I fix the P0139 code?
Repairs may include replacing the oxygen sensor, fixing wiring issues, addressing exhaust leaks, or resolving underlying engine problems affecting the air-fuel mixture.
How do I know if the oxygen sensor is faulty?
A faulty oxygen sensor may show slow voltage changes or inconsistent readings when monitored with a scan tool.
Can an exhaust leak trigger the P0139 code?
Yes, an exhaust leak near Bank 1, Sensor 2 can affect the sensor's ability to properly detect oxygen levels, causing the code to trigger.
Does a P0139 code affect emissions?
Yes, a slow-responding oxygen sensor can lead to inefficient combustion and higher emissions.
Should I clear the P0139 code after repairs?
Yes, after completing repairs, you should clear the code using a scan tool and test drive the vehicle to ensure the issue is resolved.
Discuss the causes and fixes for P0139 OBDII Code
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