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

P2609

Intake Air Heater System Performance

The intake air heater system did not raise intake temperature by the expected amount during cold-start support. Suggests low current draw, poor connection to the grid, or a failed temperature feedback path.

SystemPowertrain
Typegeneric / SAE
GroupP2
Range / number6 / 09

Possible causes

  • High-resistance battery feed to the heater high
  • Intake air temperature sensor reads with offset medium

Inspection / repair

  • Difficulty: medium
  • DIY: shop recommended
  • Estimated cost: 100–800 €
  • Estimated time: 0.8–3 h
  • Component: intake air heater
  • Component: intake air temperature sensor
  • Component: heater relay
  • MIL / check engine light
  • emissions-relevant

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