P0139 2018 Toyota RAV4 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 2018 Toyota RAV4 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 2018 Toyota RAV4 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 2018 Toyota RAV4?
- 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 2018 Toyota RAV4?
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 2018 Toyota RAV4 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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Frequently Asked Questions about P0139 2018 Toyota RAV4 Code
1. What does OBDII code P0139 on a 2018 Toyota RAV4 indicate?
This code, "Oxygen Sensor Circuit Slow Response Bank 1 Sensor 2," points to a potential issue with the oxygen sensor downstream of the catalytic converter.
2. What are the common symptoms of a P0139 code on a 2018 Toyota RAV4?
Symptoms may include decreased fuel efficiency, rough idling, engine hesitation, and an illuminated check engine light.
3. What are the possible causes of a P0139 code on a 2018 Toyota RAV4?
Causes can include a faulty oxygen sensor, wiring or connector issues, exhaust leaks, or a problem with the catalytic converter.
4. How can I diagnose the source of a P0139 code on my 2018 Toyota RAV4?
Diagnosing the issue may involve using an OBDII scanner to retrieve the code, checking the sensor's wiring and connectors for damage, and conducting tests to determine the sensor's response time.
5. Can I continue driving my 2018 Toyota RAV4 with a P0139 code?
It's generally not recommended to ignore a P0139 code, as it can lead to decreased performance and potential damage to the catalytic converter over time.
6. How can I repair a P0139 code on my 2018 Toyota RAV4?
Repairs may involve replacing the oxygen sensor (Bank 1 Sensor 2), fixing any wiring or connector issues, addressing exhaust leaks, or replacing the catalytic converter if necessary.
7. Are there any DIY tips for addressing a P0139 code on a 2018 Toyota RAV4?
While some basic checks like inspecting wiring connections can be done by DIY enthusiasts, diagnosing and repairing the root cause of the code may require professional expertise.
8. How much does it cost to fix a P0139 code on a 2018 Toyota RAV4?
The cost of repairs can vary depending on the specific cause of the issue, but it's advisable to budget for potential expenses related to sensor replacement, wiring repairs, or catalytic converter replacement.
9. How long does it take to repair a P0139 code on a 2018 Toyota RAV4?
The repair time can vary depending on the extent of the issue and the availability of parts. Simple fixes like sensor replacement may take a few hours, while more complex issues could require more time.
10. Can a P0139 code on a 2018 Toyota RAV4 cause other problems if left unresolved?
Ignoring a P0139 code can lead to poor engine performance, increased emissions, and potential damage to the catalytic converter, which can result in more costly repairs down the line.
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