OBD code P0138 indicates a problem with the rear heated oxygen sensor in bank 1 of the vehicle’s exhaust system.
Symptoms include the engine light being on, high fuel consumption, and excessive smoke from the exhaust.
This issue can be caused by a faulty sensor, wiring harness issues, fuel system problems, or exhaust leaks.
It is a moderate concern that should be addressed promptly.
To fix it, inspect the sensor, wiring harness, and connectors for any damage or poor connections.
| Repair Importance Level | 6.67 (Out of 10) |
| Estimated Repair Time | Approximately 1.0 hour |
| Repair Difficulty Level | 6.67 (Out of 10) |
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Symptoms of the p0138 OBD Code
The vehicle may experience issues related to the oxygen sensor circuit high voltage (Bank 1, Sensor 2).
- With OBD code P0138, the Engine Light will be ON.
- High Fuel Consumption can be noticed.
- Excessive Smoke from Exhaust may be present.
Causes of the p0138 OBD Code
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P0138 code typically indicates a fault in the oxygen sensor circuit high voltage.
- P0138 can be caused by a Faulty Rear Heated Oxygen Sensor Bank 1.
- A Rear Heated Oxygen Sensor Bank 1 harness that is open or shorted.
- A Rear Heated Oxygen Sensor Bank 1 circuit with poor electrical connection.
- Low or high fuel system pressure.
- Fuel contamination.
- Faulty fuel injectors.
- Exhaust gas leaks.
- Engine vacuum leaks.
Fixing Error Code p0138 Step By Step
Replace faulty oxygen sensor bank 1 sensor 2 to address P0138 code.
- To fix OBDII code P0138, first, review the ‘Possible Causes’ mentioned above and visually examine the corresponding wiring harness and connectors.
- Ensure to check for any damaged components and inspect the connector pins for signs of being broken, bent, pushed out, or corroded.
- Next, check the wiring going to the oxygen sensor for any damage or corrosion.
- Test the oxygen sensor’s heater circuit for proper operation.
- Replace the oxygen sensor if necessary.
- Clear the fault codes and perform a road test to verify the repair.
Cost Of Fixing p0138 Fault Code
Repairing fault code P0138 typically involves replacing the oxygen sensor in the bank 1 sensor 2 location.
The cost to diagnose and fix OBD code P0138 typically ranges from $75 to $150, with an estimated repair time of 1. 0 hour.
Costs depend on labor rates, complexity of the issue, and any additional parts needed for the repair.
Details of the p0138 OBD Code
P0138 indicates a high voltage condition in the downstream oxygen sensor.
OBD code P0138 means that the O2 sensor circuit voltage is high for bank 1 sensor 2. This code is triggered by the Engine Control Module (ECM) when it detects that the voltage signal from the downstream O2 sensor after the catalytic converter is higher than normal.
This indicates a potential issue with the catalytic converter efficiency or a problem with the downstream O2 sensor itself.
Mechanic’s Tech Notes
Code P0138 indicates a high voltage condition in the downstream oxygen sensor.
To diagnose and fix OBDII code P0138, which indicates a high voltage condition in the downstream oxygen sensor (Bank 1, Sensor 2), start by checking the sensor’s wiring harness and connectors for any damage or corrosion.
Use a voltmeter to test the sensor’s voltage output while the engine is running.
If the voltage is consistently high, the sensor may be faulty and need replacement.
Additionally, ensure there are no exhaust leaks near the sensor that could be affecting its readings.
If all checks out, consider reprogramming the engine control module (ECM) as a last resort.
FAQ
OBD code P0138 means Rear Heated Oxygen Sensor Bank 1 high voltage. Symptoms include Engine Light ON, high fuel consumption, and excessive smoke. Check sensor and wiring for issues.
Common causes of OBD code P0138 include a faulty rear heated oxygen sensor Bank 1, open/shorted sensor harness, poor electrical connection, fuel system issues, and exhaust/engine vacuum leaks.
Diagnose and fix OBD code P0138 by checking rear oxygen sensor, wiring, fuel system, and exhaust for issues. Inspect connectors and wiring for damage or corrosion.
Wrap Up
If your check engine light is on and you see OBDII code P0138, it may indicate a fault with the downstream oxygen sensor in bank 1. This could be caused by a faulty sensor, wiring issues, or a rich fuel mixture affecting sensor readings.
To address P0138, start by inspecting the wiring harness and connectors for any damage or corrosion.
Test the oxygen sensor’s operation and replace it if necessary.
Ensure the sensor is receiving proper voltage and that there are no exhaust leaks affecting its readings.
