P0139 Code - O2 Sensor Circuit Slow Response Bank 1 Sensor 2
Quick Answer
The Heated Oxygen Sensor 2 (HO2S), after three way catalyst (manifold), monitors the oxygen level in the exhaust gas on each bank. Common causes include Faulty Rear Heated Oxygen Sensor Bank 1, Rear Heated Oxygen Sensor Bank 1 harness is open or shorted, Rear Heated Oxygen Sensor Bank 1 circuit poor electrical connection. 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 Rear Heated Oxygen Sensor Bank 1, Rear Heated Oxygen Sensor Bank 1 harness is open or shorted, Rear Heated Oxygen Sensor Bank 1 circuit poor electrical connection.
- 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.
Code P0139 Description
What are the Possible Causes of the DTC P0139?
- Faulty Rear Heated Oxygen Sensor Bank 1
- Rear Heated Oxygen Sensor Bank 1 harness is open or shorted
- Rear Heated Oxygen Sensor Bank 1 circuit poor electrical connection
- Inappropriate fuel pressure
- Faulty fuel injectors
- Intake air leaks may be faulty
- Exhaust gas leaks
How to Fix the DTC P0139?
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.
Code Tech Notes
What is the Cost to Diagnose the Code?
Labor: 1.0
To diagnose the P0139 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
- 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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