Subaru P0138
O2 Sensor Circuit High Voltage Bank 1 Sensor 2 • P0140: O2 Sensor Circuit No Activity Detected Bank 1 Sensor 2 • P0141: O2 Sensor Heater C
Quick answer
For applicable 2019–2023 Subaru Crosstrek vehicles in the US, verified evidence identifies P0138 as “O2 Sensor Circuit High Voltage Bank 1 Sensor 2.” The same official communication also lists P0140 and P0141. Driving, charging, severity, and a specific repair are not yet established by verified evidence.
This page separates verified manufacturer/regulator evidence from supporting material. Unsupported causes, repairs or safety conclusions are not guessed.
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1. What does P0138 mean?
For applicable 2019–2023 Subaru Crosstrek vehicles in the US, verified evidence identifies P0138 as “O2 Sensor Circuit High Voltage Bank 1 Sensor 2.” The same official communication also lists P0140 and P0141. Driving, charging, severity, and a specific repair are not yet established by verified evidence.
2. Technical explanation
P0138 is an Engine Control Module (ECM) diagnostic trouble code identified in the verified NHTSA-posted Subaru manufacturer communication as “O2 Sensor Circuit High Voltage Bank 1 Sensor 2.” The supplied evidence also identifies P0140 as “O2 Sensor Circuit No Activity Detected Bank 1 Sensor 2” and P0141 as “O2 Sensor Heater C.”
3. What system is affected?
Engine Control Module (ECM); Bank 1 Sensor 2 oxygen-sensor circuit.
4. How serious is this code?
Not yet established by verified evidence.
5. Symptoms you may notice
Not yet established by verified evidence.
6. Possible causes
Not yet established by verified evidence. A diagnostic identifier alone is not proof that a specific component has failed.
7. Can I still drive the vehicle?
Not yet established by verified evidence.
8. Can I charge the vehicle?
Not yet established by verified evidence.
9. What you can safely do
- Arrange diagnosis by a qualified Subaru service provider if P0138 is present.
- Do not perform high-voltage system repairs based on this information.
10. Step-by-step troubleshooting
- A qualified service provider can confirm the ECM-stored DTC and diagnose the applicable O2 sensor circuit. Further diagnostic procedure details are not included in the supplied verified evidence.
11. When to contact service
Contact a Subaru dealer or qualified service provider for diagnosis. Service urgency is not yet established by verified evidence.
12. What the service center may check
- Confirm whether P0138, P0140, or P0141 is stored in the Engine Control Module.
- Use applicable Subaru service information for further diagnosis; specific checks are not established by the supplied verified evidence.
13. Possible repair or resolution
Not yet established by verified evidence.
14. Affected vehicles
- Subaru Crosstrek · 2019–2023 · US
15. Related TSBs / service bulletins
- NHTSA Manufacturer Communication 11017437, Subaru communication 09-115-24R, published April 22, 2025. Verified summary lists P0137, P0138, P0140, and P0141 as ECM DTCs.
16. Recall information
No recall relationship is established by verified evidence.
17. Official manufacturer information
Official source: NHTSA Manufacturer Communication 11017437, Subaru 09-115-24R: https://static.nhtsa.gov/odi/ffdd/tsbs/TSBS_RECEIVED_2025-2026.zip#nhtsa_id=11017437
- NHTSA: NHTSA Manufacturer Communication 11017437: 09-115-24R · official_tsb
19. Frequently asked questions
What does Subaru code P0138 mean?
Verified evidence identifies P0138 as “O2 Sensor Circuit High Voltage Bank 1 Sensor 2.”
Which vehicles are covered by the supplied applicability evidence?
The supplied evidence applies P0138 to US-market 2019–2023 Subaru Crosstrek vehicles.
Is it safe to drive with P0138?
Not yet established by verified evidence.
Does P0138 affect EV charging?
Not yet established by verified evidence.
What related codes are listed in the official communication?
The verified communication lists P0137, P0140, and P0141 alongside P0138.