OBD-II reference

All 9.533 generic OBD-II codes, explained in detail.

Causes, inspection steps and sources — a comprehensive DIY archive. Created and maintained with love for the detail. Good luck and have fun!

Powertrain generic / SAE

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.

SystemPowertrain
Typegeneric / SAE
GroupP0
Range / number1 / 34

Possible causes

  • Sensor aged or poisoned (silicone, lead, coolant) high
  • Sensor heater circuit weak medium
  • Exhaust leak upstream of sensor diluting reading medium

Symptoms

  • Check engine light on
  • Increased fuel consumption
  • Possible rough idle or hesitation
  • Failed emissions test

Inspection / repair

  • Difficulty: easy
  • DIY: possible
  • Estimated cost: 80–350 €
  • Estimated time: 0.3–1.5 h
  • Component: oxygen sensor b1s1
  • Component: oxygen sensor heater circuit
  • Component: exhaust manifold gasket
  • MIL / check engine light
  • emissions-relevant
  • drive cycle required

Sources

References

How to read OBD-II codes

The first letter names the vehicle system, the second digit distinguishes generic from manufacturer-specific, the remaining digits group fault area and number.

PPowertrain: engine, transmission, emissions
BBody: chassis trim, comfort, interior
CChassis: suspension, brakes, steering
UNetwork: CAN, control modules, communication