Powertrain, generic · Fuel and air metering

P0134 O2 Sensor Circuit No Activity Detected Bank 1 Sensor 1

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

The oxygen sensor before the catalytic converter on bank 1 (sensor 1) is the main control sensor for the mixture. It is either a switching sensor (about 0.1 V lean to 0.9 V rich) or a wide-band sensor that works with a pump current evaluated by an interface chip. P0134 means the sensor delivers no moving signal, typically because the circuit is open or the cell is cold or dead. The control module feeds a bias voltage, and that is all it sees: GM fails a signal stuck at 350–550 mV (or above 1700 mV with a 1.9 V bias) after warm-up, within about 15 s, or a cell resistance above 20 kΩ in hot exhaust; two trips. Subaru's wide-band sensor fails above 500 Ω cell impedance with immediate MIL. Ford's Bosch wide-band systems have used P2237 for this since 2011. A stored code usually switches mixture control to open loop and suspends adaptation and converter monitoring.

Likely causes

Open or high-resistance signal or ground wire, connector loose or corroded
Sensor faulty (cell high-resistance, worn out)
Sensor heater faulty – sensor does not get hot enough
Exhaust leak ahead of the sensor or cracked sensor
Control module bias or measuring circuit faulty

Symptoms

  • Check engine light on
  • No mixture control (open loop), higher consumption
  • Higher emissions, possible emissions test failure

Repair estimate

DifficultyMediumDIY possible
Parts and labour€50–350
Time0.5–2 h

Typical range across vehicles; the real cost depends on what the testing finds.

What to check first

  1. Check heater and signal circuits
  2. Inspect connector
  3. Replace sensor if dead

Parts involved

oxygen sensor bank1 sensor1oxygen sensor wiringengine control module

Related codes

P0133P0135P0131P0132P0154P2237

References: law.cornell.edu, gsi.ext.gm.com, saabwisonline.com, saabwisonline.com.