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

P016C

Closed Loop Air/Fuel Ratio Control At Limit - System Too Lean

Closed-loop fuel trim hit its rich correction limit because mixture is structurally too lean. Likely vacuum leak, low fuel pressure, or contaminated MAF.

SystemPowertrain
Typegeneric / SAE
GroupP0
Range / number1 / 6C

Possible causes

  • Vacuum leak high

Symptoms

  • Check engine light on
  • Rough idle, possible stalling
  • Hesitation or hard cold start
  • Power loss under load

Inspection / repair

  • Difficulty: medium
  • DIY: possible
  • Estimated cost: 50–1500 €
  • Estimated time: 0.5–5 h
  • Component: intake system
  • Component: fuel pressure regulator
  • Component: mass air flow sensor
  • MIL / check engine light
  • emissions-relevant
  • drive cycle required
  • limp mode possible

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