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

P04E4

Crankcase Ventilation Hose Connection Sensor Circuit Intermittent or Erratic

Same as P04E1 with intermittent or erratic signal. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.

SystemPowertrain
Typegeneric / SAE
GroupP0
Range / number4 / E4

Possible causes

  • Intermittent contact at connector high
  • Connector with intermittent contact under vibration low
  • Harness routed against vibrating component low

Inspection / repair

  • Difficulty: easy
  • DIY: possible
  • Estimated cost: 60–250 €
  • Estimated time: 0.4–1.2 h
  • Component: pcv hose connection sensor
  • Component: pcv hose wiring
  • 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