OBD-II code · Powertrain (generic)
P0134 O2 Sensor Circuit No Activity / Slow Response (Bank 1 Sensor 1)
The ECU detects that the upstream oxygen sensor on bank 1 shows no switching activity or responds too slowly to changing exhaust gas composition. Often the sensor is aged, contaminated by silicone or fuel additives, or the heater circuit is degraded.
Is it safe to drive with P0134?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelySensor aged or poisoned (silicone, lead, coolant)
- PossibleSensor heater circuit weak
- PossibleExhaust leak upstream of sensor diluting reading
Symptoms
- Check engine light on
- Increased fuel consumption
- Possible rough idle or hesitation
- Failed emissions test
Repair at a glance
- Difficulty
- Easy
- DIY friendly
- Often, with basic tools
- Typical labour
- 0.3–1.5 h
- Emissions test
- Likely to fail
- After the fix
- A drive cycle is needed before the light stays off
- Parts involved
- Oxygen Sensor B1s1, Oxygen Sensor Heater Circuit, Exhaust Manifold Gasket
Related codes
- P0140O2 Sensor Circuit No Activity / Slow Response (Bank 1 Sensor 2)
- P0146O2 Sensor Circuit No Activity / Slow Response (Bank 1 Sensor 3)
- P0154O2 Sensor Circuit No Activity / Slow Response (Bank 2 Sensor 1)
- P0160O2 Sensor Circuit No Activity / Slow Response (Bank 2 Sensor 2)
- P0166O2 Sensor Circuit No Activity / Slow Response (Bank 2 Sensor 3)
- P0131O2 Sensor Circuit Low Voltage (Bank 1, Sensor 1)
- P0132O2 Sensor Circuit High Voltage (Bank 1, Sensor 1)
- P0133O2 Sensor Slow Response (Bank 1, Sensor 1)
- P0135O2 Sensor Heater Circuit Malfunction (Bank 1, Sensor 1)
- P0136O2 Sensor Circuit Malfunction (Bank 1, Sensor 2)
- P0137O2 Sensor Circuit Low Voltage (Bank 1, Sensor 2)
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.