P0138 Lexus Code - Oxygen Sensor Circuit High Voltage 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
- P0138 Lexus indicates Oxygen Sensor Circuit High Voltage 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 P0138 Lexus 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 Diagnostic Trouble Code (DTC) P0138 is stored if the heated oxygen sensor voltage output is 1.2 V or higher for 10 seconds or more.
What are the Possible Causes of the DTC P0138 Lexus?
- 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 P0138 Lexus?
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 P0138 Lexus 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 P0138 Lexus Code
1. What are the common symptoms of OBDII code P0138 in a Lexus related to the Oxygen Sensor Circuit High Voltage Bank 1 Sensor 2?
- Common symptoms include poor fuel economy, rough idling, loss of power, and the illumination of the Check Engine Light.
2. What are the potential causes of OBDII code P0138 in a Lexus?
- The code P0138 in a Lexus is typically triggered by a faulty oxygen sensor, damaged wiring or connectors, exhaust leaks, or issues with the engine's computer.
3. How can I diagnose the Oxygen Sensor Circuit High Voltage Bank 1 Sensor 2 issue in my Lexus?
- Diagnosis involves using an OBDII scanner to retrieve the specific fault code, inspecting the oxygen sensor and related wiring for damage, and checking for exhaust leaks.
4. Can a faulty oxygen sensor cause the OBDII code P0138 in a Lexus?
- Yes, a faulty oxygen sensor, particularly Bank 1 Sensor 2, can trigger the high voltage condition leading to the P0138 code.
5. What are some repair tips for addressing OBDII code P0138 in a Lexus?
- Repair tips include replacing the faulty oxygen sensor, repairing damaged wiring or connectors, fixing any exhaust leaks, and resetting the Check Engine Light.
6. Is it safe to continue driving my Lexus with the OBDII code P0138 related to the Oxygen Sensor Circuit High Voltage Bank 1 Sensor 2?
- It is generally not recommended to drive with the P0138 code as it can lead to decreased fuel efficiency and potential damage to the catalytic converter.
7. How much does it typically cost to repair OBDII code P0138 in a Lexus?
- The cost of repairing the P0138 code can vary depending on the specific issue, but it may range from $100 to $300 for parts and labor.
8. Can I reset the Check Engine Light after fixing the OBDII code P0138 in my Lexus?
- Yes, after addressing the underlying issue causing the P0138 code, you can reset the Check Engine Light using an OBDII scanner or by disconnecting the car's battery for a few minutes.
9. Are there any DIY solutions for fixing the OBDII code P0138 in a Lexus?
- While some may attempt DIY repairs for the P0138 code, it is recommended to consult a professional mechanic due to the complexity of diagnosing and repairing issues related to oxygen sensors and engine components.
10. How long does it typically take to repair the Oxygen Sensor Circuit High Voltage Bank 1 Sensor 2 issue causing OBDII code P0138 in a Lexus?
- The repair time for addressing the P0138 code can vary depending on the specific cause, but it may take anywhere from 1 to 3 hours at a repair shop.
Discuss the causes and fixes for P0138 Lexus OBDII Code
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tengo una lexus gx 470 modelo 2007.. el problema empeso cuando reemplase el exosto porque se rompio, en el taller cambiaron exactamente despues del O2 posterior de cada banco y el codigo empeso a estableserce como (baja eficiencia del catalizador banco 1)
intercambie los sensores de O2 y persistia el codigo en el banco 1. luego reemplace el catalizador del banco por otro generico y ahora el codigo que se presenta es P0138, (voltage alto en el sensor O2 banco1 sensor 2), en ralenti permanese en 850mv mientras el otro permanese en 200mv , invierto los sensores y ocurre lo mismo..podria afectar la forma como empalmaron los tubos porque estos se unen en un solo tubo y no me parese que eso quedo como estaba anteriormente? -
Si puede afectar. Tambien si tiene alguna fuga en el exhaust puede afectar.
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i have lexus is 250 w/heather then a have a code for over heater sensor what can i do ..
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