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

P2B8D

Intake Air O2 Sensor Heater Control Circuit Low Bank 1

Voltage on the intake air O2 sensor heater control line on bank 1 is below the expected window. Wire shorted to ground or heater element shorted.

SystemPowertrain
Typegeneric / SAE
GroupP2
Range / numberB / 8D

Possible causes

  • Heater wire shorted to ground high
  • Heater element shorted medium
  • Connector pins corroded - high contact resistance low

Symptoms

  • Check engine light on after several drive cycles
  • Slightly increased fuel consumption during cold start
  • Delayed entry into closed-loop fuel control
  • Failed emissions inspection (lambda readiness)

Inspection / repair

  • Difficulty: medium
  • DIY: shop recommended
  • Estimated cost: 150–800 €
  • Estimated time: 0.5–3 h
  • Component: intake air o2 sensor b1
  • Component: intake air o2 sensor heater b1
  • Component: wiring harness
  • Component: ecm
  • 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