P0134 Code: O2 Sensor Circuit No Activity Detected (Bank 1 Sensor 1)
🟠 Moderate severity · drivable
Drivable, but the computer has no fuel-control feedback, so economy and running will suffer.
What P0134 means
The bank 1 upstream oxygen sensor is producing no signal at all — the computer has lost its primary fuel-control feedback. This is different from a slow or biased sensor: the sensor is either dead, unplugged, or its wiring is open.
Symptoms
- Check engine light on
- Poor fuel economy
- Rough running
- Possible failed emissions test
Common causes
- most common: Faulty upstream oxygen sensor (dead)
- common: Open or damaged sensor wiring
- less common: Loose or corroded sensor connector
How to fix it
| Fix | DIY? | Typical cost |
|---|---|---|
| Replace the bank 1 upstream oxygen sensor | Yes | $60–200 |
| Repair open sensor wiring or connector | Mechanic | $50–150 |
Frequently asked questions
What's the difference between P0134 and P0130?
P0130 is a general circuit fault; P0134 specifically means the sensor is producing no signal at all — it's dead or disconnected.
What's the most common cause of P0134?
A dead upstream oxygen sensor, or broken wiring to it.
How much does it cost to fix P0134?
Typically $60–$200 for a new oxygen sensor.
Related codes
P0130
P0130 Code: O2 Sensor Circuit Malfunction (Bank 1 Sensor 1)
P0133P0133 Code: O2 Sensor Circuit Slow Response (Bank 1 Sensor 1)
P0135P0135 Code: O2 Sensor Heater Circuit Malfunction (Bank 1 Sensor 1)
Related guide: MAF Sensor Replacement Cost →
Updated 2026-08. This page is informational and not a substitute for professional diagnosis.