P0139 Toyota Code - Oxygen Sensor Circuit Slow Response Bank 1 Sensor 2
Quick Answer
In order to obtain a high purification rate of the Carbon Monoxide (CO), Hydrocarbon (HC), and Nitrogen Oxide (NOx) components in the exhaust gas, a Three-Way Catalytic Converter (TWC) is used. Common causes include Faulty Oxygen Sensor Bank 1 Sensor 2, Oxygen Sensor Bank 1 Sensor 2 harness is open or shorted, Oxygen Sensor Bank 1 Sensor 2 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 Toyota indicates Oxygen Sensor Circuit Slow Response Bank 1 Sensor 2.
- Common causes
- Common causes include Faulty Oxygen Sensor Bank 1 Sensor 2, Oxygen Sensor Bank 1 Sensor 2 harness is open or shorted, Oxygen Sensor Bank 1 Sensor 2 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 Toyota Description
The heated oxygen sensor is located behind the TWC and detects the oxygen concentration in the exhaust gas. Since the sensor is integrated with the heater that heats the sensing portion, it is possible to detect the oxygen concentration even when the intake air volume is low (the exhaust gas temperature is low).
When the air-fuel ratio becomes lean, the oxygen concentration in the exhaust gas is high. The heated oxygen sensor informs the ECM that the post-TWC air-fuel ratio is lean (low voltage, i.e. less than 0.45 V).
Conversely, when the air-fuel ratio is richer than the stoichiometric air-fuel level, the oxygen concentration in the exhaust gas is low. The heated oxygen sensor informs the ECM that the post-TWC air-fuel ratio is rich (high voltage, i.e. more than 0.45 V). The heated oxygen sensor has the property of changing its output voltage drastically when the air-fuel ratio is close to the stoichiometric level.
The ECM uses the supplementary information from the heated oxygen sensor to determine whether the air-fuel ratio after the TWC is rich or lean and adjusts the fuel injection duration accordingly. Thus, if the heated oxygen sensor is working improperly due to internal malfunctions, the ECM is unable to compensate for deviations in the primary air-fuel ratio control.
The ECM continuously monitors the heated oxygen sensor output voltage while the engine is running. The sensor output voltage drops to below 0.2 V (extremely lean status) immediately when the vehicle decelerates, and the fuel cut is operating. If the voltage does not drop to below 0.2 V for 7 seconds or more, the ECM determines that the sensor response has deteriorated, illuminates the MIL, and stores a Diagnostic Trouble Code (DTC).
What are the Possible Causes of the DTC P0139 Toyota?
- Faulty Oxygen Sensor Bank 1 Sensor 2
- Oxygen Sensor Bank 1 Sensor 2 harness is open or shorted
- Oxygen Sensor Bank 1 Sensor 2 circuit poor electrical connection
- Gas leak from exhaust system
How to Fix the DTC P0139 Toyota?
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 Toyota 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 Toyota Models
- P0139 2013 Toyota RAV4 — Oxygen Sensor Circuit Slow Response Bank 1 Sensor 2
- P0139 2014 Toyota RAV4 — Oxygen Sensor Circuit Slow Response Bank 1 Sensor 2
- P0139 2015 Toyota RAV4 — Oxygen Sensor Circuit Slow Response Bank 1 Sensor 2
- P0139 2016 Toyota RAV4 — Oxygen Sensor Circuit Slow Response Bank 1 Sensor 2
- P0139 2017 Toyota RAV4 — Oxygen Sensor Circuit Slow Response Bank 1 Sensor 2
- P0139 2018 Toyota RAV4 — Oxygen Sensor Circuit Slow Response Bank 1 Sensor 2
- P0139 Toyota RAV4 — HO2S12 Circuit Slow Response
Frequently Asked Questions about P0139 Toyota Code
No Frequently Asked Questions about P0139 Toyota Code found.
Discuss the causes and fixes for P0139 Toyota OBDII Code
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can a p0136 code be cause by the catalytic converter being clogged or failing. I smell a sulfur fart smell from exhaust . and it has not power pulling up hill getting on highway I'm always getting the finger. it idles rough at stop lights. 2002 Toyota Tacoma 2.7 4 cylinder motor.
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Yes, if the P0136 code could be triggered by a faulty or clogged catalytic converter.
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thank you. Well I have 2 catalytic converters I'm not sure but think I must replace both. local auto parts store say 300 a piece. So any clue where I can find the two connected as one unit cheaper . do you think the o2 sensors will be fine. I'm just a single dad and cant pay a mechanic to track it down so I must do it myself hoping I cant find my two cats cheaper than 600 2002 Toyota Tacoma 2.7 4cyl 2w
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I recommend remove the catalytic converters and inspect which converter has come apart. Usually the the front one comes apart and clogged the second one. If is clogged, you could just remove all the debris.
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