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

P28A6

Cylinder 6 Ion Current Sense Circuit Low

Ion current from cylinder 6 is below the expected window. Spark plug fouled, signal wire shorted to ground, or sensing path interrupted.

SystemPowertrain
Typegeneric / SAE
GroupP2
Range / number8 / A6

Possible causes

  • Spark plug fouled with carbon or oil high
  • Sense wire shorted to ground medium
  • Connector pins corroded - high contact resistance low

Inspection / repair

  • Difficulty: medium
  • DIY: shop recommended
  • Estimated cost: 100–700 €
  • Estimated time: 0.5–3 h
  • Component: spark plug cyl 6
  • Component: ignition coil cyl 6
  • Component: ion sense module
  • 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