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

P2099

Post Catalyst Fuel Trim System Too Rich (Bank 2)

Bank 2 counterpart of P2097. Post-catalyst trim on bank 2 has reached the rich limit — usually a depleted catalyst or a downstream sensor biased rich on the bank 2 side.

SystemPowertrain
Typegeneric / SAE
GroupP2
Range / number– / 99

Possible causes

  • Bank 2 catalyst oxygen storage exhausted high
  • Bank 2 downstream sensor biased rich medium

Symptoms

  • Check engine light on
  • Failed emissions inspection
  • Possibly slightly increased fuel consumption
  • Sulfur (rotten egg) smell from exhaust under load

Inspection / repair

  • Difficulty: medium
  • DIY: possible
  • Estimated cost: 60–1500 €
  • Estimated time: 0.5–4 h
  • Component: oxygen sensor downstream
  • Component: catalytic converter
  • 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