Powertrain, generic · Auxiliary emission controls

P04E4 Crankcase Ventilation Hose Connection Sensor Circuit Intermittent/Erratic

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

The crankcase ventilation (PCV) system routes blow-by gas from the crankcase into the intake; CARB requires a disconnection between crankcase and intake to be detected. GM's 2.0-litre LSY has a pressure sensor in the PCV hose: with the hose connected it must see a pressure drop that grows with air flow, plus pressure pulses from the pistons. Ford reports the same sensor type as crankcase pressure sensor A (P051A ff). P04E4 means the sensor signal jumps or drops out briefly – usually a loose contact, a chafed wire or a measuring port blocked by oil sludge or ice. The disconnection check P04DB is then suspended or may report falsely. No manufacturer document available to us uses this code; the description follows the GM sibling codes P04E2/P04E3 and CARB.

Likely causes

Loose contact at the sensor connector
Chafed wire with intermittent short
Sensor faulty or measuring port blocked (oil sludge, ice)
Engine module

Symptoms

  • Check engine light on
  • Disconnection check P04DB does not run
  • Usually no change in driving

Repair estimate

DifficultyEasyDIY possible
Parts and labour€50–250
Time0.3–2 h

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

Parts involved

crankcase ventilation hose sensorsensor wiringengine control module

Related codes

P04E1P04E2P04E3P04FBP04DBP051E

References: gsi.ext.gm.com, fordservicecontent.com, law.cornell.edu.