Powertrain, generic · Vehicle speed, idle control and auxiliary inputs

P05D9 PCV Regulator Valve Control Circuit Low

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

Some turbo engines have an electrically controlled crankcase ventilation valve that decides when and how much blow-by gas is drawn into the intake (part-load versus full-load path). The engine module monitors its driver output; CARB requires output components to be checked for circuit faults and the PCV system to be monitored. Nissan's 1.5 L KR15DDT (Rogue 2024–25) sets P05D8/P05D9 with the warning lamp from a severed harness at the valve; Mercedes M270/M274 have such a valve but report it under P052E. P05D9 means the control line is too low – a short to ground of the control or supply line, or with a low-side driver too low a voltage when off.

Likely causes

Damaged harness shorted to ground
Valve shorted internally
Moisture or oil in the connector
Engine module

Symptoms

  • Check engine light on
  • Often no noticeable symptoms
  • If the valve sticks: oil mist, blue smoke, rough idle

Repair estimate

DifficultyMediumDIY possible
Parts and labour€60–500
Time0.5–2 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

pcv regulator valvevalve wiringengine control module

Related codes

P05D8P05DAP052EP04DBP053AP051A

References: static.nhtsa.gov, static.nhtsa.gov, law.cornell.edu.