All codes › P0138
P0138: O2 Sensor Circuit High Voltage (Bank 1 Sensor 2)
What it means
Voltage from the downstream O2 sensor on bank 1 (after the catalytic converter), which monitors converter efficiency is stuck high.
Severity: Low Emissions-only impact.
Common causes
- Failed sensor
- Wiring shorted to voltage
- Rich running
- Contaminated sensor
Most common causes first. Exact causes vary by make, model and engine.
Can I fix it myself?
Often DIY. Wiring rubbing on the exhaust is a common cause.
Repair cost
SEEDED ESTIMATE Roughly $70–$330
Most likely repair: oxygen sensor. Diagnosis fees, taxes and other causes are not included.
| Line | Low | High | Basis |
|---|---|---|---|
| Oxygen sensor | $36 | $168 | Typical listed retail range, source |
| Labor 0.3–1 hr | $30 | $160 | $100–$160/hr, shop survey |
⚠️ This is an editorial placeholder range for this type of repair. It is not based on real invoices or licensed pricing data yet. Real ranges will appear here once enough reader invoices for P0138 are verified.
Verified reader invoices for P0138: 0. Share your repair bill to help build real costs.
Tools that can read P0138
- ScanFixAI: Pro $29.99/mo or $249.99/yr
- OBDAI: Annual PRO bundle $299
- BlueDriver Pro Next-Gen: $119.95 list ($99.95 sale seen)
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